Module ngx_http_core_module

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Module ngx_http_core_module

Directives
absolute_redirect
aio
aio_write
alias
auth_delay
chunked_transfer_encoding
client_body_buffer_size
client_body_in_file_only
client_body_in_single_buffer
client_body_temp_path
client_body_timeout
client_header_buffer_size
client_header_timeout
client_max_body_size
connection_pool_size
default_type
directio
directio_alignment
disable_symlinks
early_hints
error_log_tag
error_page
etag
http
if_modified_since
ignore_invalid_headers
internal
keepalive_disable
keepalive_min_timeout
keepalive_requests
keepalive_time
keepalive_timeout
large_client_header_buffers
limit_except
limit_rate
limit_rate_after
lingering_close
lingering_time
lingering_timeout
listen
location
log_not_found
log_subrequest
max_headers
max_ranges
merge_slashes
msie_padding
msie_refresh
open_file_cache
open_file_cache_errors
open_file_cache_min_uses
open_file_cache_valid
output_buffers
port_in_redirect
postpone_output
read_ahead
recursive_error_pages
request_pool_size
reset_timedout_connection
resolver
resolver_timeout
root
satisfy
send_lowat
send_timeout
sendfile
sendfile_max_chunk
server
server_name
server_name_in_redirect
server_names_hash_bucket_size
server_names_hash_max_size
server_tokens
subrequest_output_buffer_size
tcp_nodelay
tcp_nopush
try_files
types
types_hash_bucket_size
types_hash_max_size
underscores_in_headers
variables_hash_bucket_size
variables_hash_max_size
Embedded Variables

Directives

Syntax:

absolute_redirect on | off;

Default:

absolute_redirect on;

Context:

http, server, location

This directive appeared in version 1.11.8.

If disabled, redirects issued by nginx will be relative.

See also server_name_in_redirect
and port_in_redirect directives.

Syntax:

aio
on |
off |
threads[=pool];

Default:

aio off;

Context:

http, server, location

This directive appeared in version 0.8.11.

Enables or disables the use of asynchronous file I/O (AIO)
on FreeBSD and Linux:

location /video/ {
aio on;
output_buffers 1 64k;
}

On FreeBSD, AIO can be used starting from FreeBSD 4.3.
Prior to FreeBSD 11.0,
AIO can either be linked statically into a kernel:

options VFS_AIO

or loaded dynamically as a kernel loadable module:

kldload aio

On Linux, AIO can be used starting from kernel version 2.6.22.
Also, it is necessary to enable
directio,
or otherwise reading will be blocking:

location /video/ {
aio on;
directio 512;
output_buffers 1 128k;
}

On Linux,
directio
can only be used for reading blocks that are aligned on 512-byte
boundaries (or 4K for XFS).
File’s unaligned end is read in blocking mode.
The same holds true for byte range requests and for FLV requests
not from the beginning of a file: reading of unaligned data at the
beginning and end of a file will be blocking.

When both AIO and sendfile are enabled on Linux,
AIO is used for files that are larger than or equal to
the size specified in the directio directive,
while sendfile is used for files of smaller sizes
or when directio is disabled.

location /video/ {
sendfile on;
aio on;
directio 8m;
}

Finally, files can be read and sent
using multi-threading (1.7.11),
without blocking a worker process:

location /video/ {
sendfile on;
aio threads;
}

Read and send file operations are offloaded to threads of the specified
pool.
If the pool name is omitted,
the pool with the name “default” is used.
The pool name can also be set with variables:

aio threads=pool$disk;

By default, multi-threading is disabled, it should be
enabled with the
--with-threads configuration parameter.
Currently, multi-threading is compatible only with the
epoll,
kqueue,
and
eventport methods.
Multi-threaded sending of files is only supported on Linux.

See also the sendfile directive.

Syntax:

aio_write on | off;

Default:

aio_write off;

Context:

http, server, location

This directive appeared in version 1.9.13.

If aio is enabled, specifies whether it is used for writing files.
Currently, this only works when using
aio threads
and is limited to writing temporary files
with data received from proxied servers.

Syntax:

alias path;

Default:

—

Context:

location

Defines a replacement for the specified location.
For example, with the following configuration

location /i/ {
alias /data/w3/images/;
}

on request of
“/i/top.gif”, the file
/data/w3/images/top.gif will be sent.

The path value can contain variables,
except $document_root and $realpath_root.

If alias is used inside a location defined
with a regular expression then such regular expression should
contain captures and alias should refer to
these captures (0.7.40), for example:

location ~ ^/users/(.+\.(?:gif|jpe?g|png))$ {
alias /data/w3/images/$1;
}

When location matches the last part of the directive’s value:

location /images/ {
alias /data/w3/images/;
}

it is better to use the
root
directive instead:

location /images/ {
root /data/w3;
}

Syntax:

auth_delay time;

Default:

auth_delay 0s;

Context:

http, server, location

This directive appeared in version 1.17.10.

Delays processing of unauthorized requests with 401 response code
to prevent timing attacks when access is limited by
password, by the
result of subrequest,
or by JWT.

Syntax:

chunked_transfer_encoding on | off;

Default:

chunked_transfer_encoding on;

Context:

http, server, location

Allows disabling chunked transfer encoding in HTTP/1.1.
It may come in handy when using a software failing to support
chunked encoding despite the standard’s requirement.

Syntax:

client_body_buffer_size size;

Default:

client_body_buffer_size 8k|16k;

Context:

http, server, location

Sets buffer size for reading client request body.
In case the request body is larger than the buffer,
the whole body or only its part is written to a
temporary file.
By default, buffer size is equal to two memory pages.
This is 8K on x86, other 32-bit platforms, and x86-64.
It is usually 16K on other 64-bit platforms.

Syntax:

client_body_in_file_only
on |
clean |
off;

Default:

client_body_in_file_only off;

Context:

http, server, location

Determines whether nginx should save the entire client request body
into a file.
This directive can be used during debugging, or when using the
$request_body_file
variable, or the
$r->request_body_file
method of the module
ngx_http_perl_module.

When set to the value on, temporary files are not
removed after request processing.

The value clean will cause the temporary files
left after request processing to be removed.

Syntax:

client_body_in_single_buffer on | off;

Default:

client_body_in_single_buffer off;

Context:

http, server, location

Determines whether nginx should save the entire client request body
in a single buffer.
The directive is recommended when using the
$request_body
variable, to save the number of copy operations involved.

Syntax:

client_body_temp_path
path
[level1
[level2
[level3]]];

Default:

client_body_temp_path client_body_temp;

Context:

http, server, location

Defines a directory for storing temporary files holding client request bodies.
Up to three-level subdirectory hierarchy can be used under the specified
directory.
For example, in the following configuration

client_body_temp_path /spool/nginx/client_temp 1 2;

a path to a temporary file might look like this:

/spool/nginx/client_temp/7/45/00000123457

Syntax:

client_body_timeout time;

Default:

client_body_timeout 60s;

Context:

http, server, location

Defines a timeout for reading client request body.
The timeout is set only for a period between two successive read operations,
not for the transmission of the whole request body.
If a client does not transmit anything within this time, the
request is terminated with the
408 (Request Time-out)
error.

Syntax:

client_header_buffer_size size;

Default:

client_header_buffer_size 1k;

Context:

http, server

Sets buffer size for reading client request header.
For most requests, a buffer of 1K bytes is enough.
However, if a request includes long cookies, or comes from a WAP client,
it may not fit into 1K.
If a request line or a request header field does not fit into
this buffer then larger buffers, configured by the
large_client_header_buffers directive,
are allocated.

If the directive is specified on the server level,
the value from the default server can be used.
Details are provided in the
“Virtual
server selection” section.

Syntax:

client_header_timeout time;

Default:

client_header_timeout 60s;

Context:

http, server

Defines a timeout for reading client request header.
If a client does not transmit the entire header within this time, the
request is terminated with the
408 (Request Time-out)
error.

Syntax:

client_max_body_size size;

Default:

client_max_body_size 1m;

Context:

http, server, location

Sets the maximum allowed size of the client request body.
If the size in a request exceeds the configured value, the
413 (Request Entity Too Large)
error is returned to the client.
Please be aware that
browsers cannot correctly display
this error.
Setting size to 0 disables checking of client
request body size.

Syntax:

connection_pool_size size;

Default:

connection_pool_size 256|512;

Context:

http, server

Allows accurate tuning of per-connection memory allocations.
This directive has minimal impact on performance
and should not generally be used.
By default, the size is equal to
256 bytes on 32-bit platforms and 512 bytes on 64-bit platforms.

Prior to version 1.9.8, the default value was 256 on all platforms.

Syntax:

default_type mime-type;

Default:

default_type text/plain;

Context:

http, server, location

Defines the default MIME type of a response.
Mapping of file name extensions to MIME types can be set
with the types directive.

Syntax:

directio size | off;

Default:

directio off;

Context:

http, server, location

This directive appeared in version 0.7.7.

Enables the use of
the O_DIRECT flag (FreeBSD, Linux),
the F_NOCACHE flag (macOS),
or the directio() function (Solaris),
when reading files that are larger than or equal to
the specified size.
The directive automatically disables (0.7.15) the use of
sendfile
for a given request.
It can be useful for serving large files:

directio 4m;

or when using aio on Linux.

Syntax:

directio_alignment size;

Default:

directio_alignment 512;

Context:

http, server, location

This directive appeared in version 0.8.11.

Sets the alignment for
directio.
In most cases, a 512-byte alignment is enough.
However, when using XFS under Linux, it needs to be increased to 4K.

Syntax:

disable_symlinks off;
disable_symlinks
on |
if_not_owner
[from=part];

Default:

disable_symlinks off;

Context:

http, server, location

This directive appeared in version 1.1.15.

Determines how symbolic links should be treated when opening files:

off

Symbolic links in the pathname are allowed and not checked.
This is the default behavior.

on

If any component of the pathname is a symbolic link,
access to a file is denied.

if_not_owner

Access to a file is denied if any component of the pathname
is a symbolic link, and the link and object that the link
points to have different owners.

from=part

When checking symbolic links
(parameters on and if_not_owner),
all components of the pathname are normally checked.
Checking of symbolic links in the initial part of the pathname
may be avoided by specifying additionally the
from=part parameter.
In this case, symbolic links are checked only from
the pathname component that follows the specified initial part.
If the value is not an initial part of the pathname checked, the whole
pathname is checked as if this parameter was not specified at all.
If the value matches the whole file name,
symbolic links are not checked.
The parameter value can contain variables.

Example:

disable_symlinks on from=$document_root;

This directive is only available on systems that have the
openat() and fstatat() interfaces.
Such systems include modern versions of FreeBSD, Linux, and Solaris.

Parameters on and if_not_owner
add a processing overhead.

On systems that do not support opening of directories only for search,
to use these parameters it is required that worker processes
have read permissions for all directories being checked.

The
ngx_http_autoindex_module,
ngx_http_random_index_module,
and ngx_http_dav_module
modules currently ignore this directive.

Syntax:

early_hints string ...;

Default:

—

Context:

http, server, location

This directive appeared in version 1.29.0.

Defines conditions under which
the 103 (Early Hints) response
will be passed to a client.
If at least one value of the string parameters is not empty and is not
equal to “0” then the response will be passed:

map $http_sec_fetch_mode $early_hints {
navigate $http2$http3;
}

server {
...
location / {
early_hints $early_hints;
proxy_pass http://example.com;
}
}

103 (Early Hints) responses received from
an upstream server are passed to a client as is, without interpretation.

Syntax:

error_log_tag name value;

Default:

—

Context:

http, server, location

This directive appeared in version 1.29.8.

Defines an additional context tag for HTTP
error log messages in
text or JSON
format, in addition to default tags.
The value can contain text, variables, and their combination:

error_log_tag request_id $request_id;

Several error_log_tag directives
can be specified on the same level.
These directives are inherited from the previous configuration level
if and only if there are no error_log_tag directives
defined on the current level.

This directive is available as part of our
commercial subscription.

Syntax:

error_page
code ...
[=[response]]
uri;

Default:

—

Context:

http, server, location, if in location

Defines the URI that will be shown for the specified errors.
A uri value can contain variables.

Example:

error_page 404 /404.html;
error_page 500 502 503 504 /50x.html;

This causes an internal redirect to the specified uri
with the client request method changed to “GET”
(for all methods other than
“GET” and “HEAD”).

Furthermore, it is possible to change the response code to another
using the “=response” syntax, for example:

error_page 404 =200 /empty.gif;

If an error response is processed by a proxied server
or a FastCGI/uwsgi/SCGI/gRPC server,
and the server may return different response codes (e.g., 200, 302, 401
or 404), it is possible to respond with the code it returns:

error_page 404 = /404.php;

If there is no need to change URI and method during internal redirection
it is possible to pass error processing into a named location:

location / {
error_page 404 = @fallback;
}

location @fallback {
proxy_pass http://backend;
}

If uri processing leads to an error,
the status code of the last occurred error is returned to the client.

It is also possible to use URL redirects for error processing:

error_page 403 http://example.com/forbidden.html;
error_page 404 =301 http://example.com/notfound.html;

In this case, by default, the response code 302 is returned to the client.
It can only be changed to one of the redirect status
codes (301, 302, 303, 307, and 308).

The code 307 was not treated as a redirect until versions 1.1.16 and 1.0.13.

The code 308 was not treated as a redirect until version 1.13.0.

These directives are inherited from the previous configuration level
if and only if there are no error_page directives
defined on the current level.

Syntax:

etag on | off;

Default:

etag on;

Context:

http, server, location

This directive appeared in version 1.3.3.

Enables or disables automatic generation of the “ETag”
response header field for static resources.

Syntax:

http { ... }

Default:

—

Context:

main

Provides the configuration file context in which the HTTP server directives
are specified.

Syntax:

if_modified_since
off |
exact |
before;

Default:

if_modified_since exact;

Context:

http, server, location

This directive appeared in version 0.7.24.

Specifies how to compare modification time of a response
with the time in the
“If-Modified-Since”
request header field:

off

the response is always considered modified (0.7.34);

exact

exact match;

before

modification time of the response is
less than or equal to the time in the “If-Modified-Since”
request header field.

Syntax:

ignore_invalid_headers on | off;

Default:

ignore_invalid_headers on;

Context:

http, server

Controls whether header fields with invalid names should be ignored.
Valid names are composed of English letters, digits, hyphens, and possibly
underscores (as controlled by the underscores_in_headers
directive).

If the directive is specified on the server level,
the value from the default server can be used.
Details are provided in the
“Virtual
server selection” section.

Syntax:

internal;

Default:

—

Context:

location

Specifies that a given location can only be used for internal requests.
For external requests, the client error
404 (Not Found)
is returned.
Internal requests are the following:

requests redirected by the
error_page,
index,
internal_redirect,
random_index, and
try_files directives;

requests redirected by the “X-Accel-Redirect”
response header field from an upstream server;

subrequests formed by the
“include virtual”
command of the
ngx_http_ssi_module
module, by the
ngx_http_addition_module
module directives, and by
auth_request and
mirror directives;

requests changed by the
rewrite directive.

Example:

error_page 404 /404.html;

location = /404.html {
internal;
}

There is a limit of 10 internal redirects per request to prevent
request processing cycles that can occur in incorrect configurations.
If this limit is reached, the error
500 (Internal Server Error) is returned.
In such cases, the “rewrite or internal redirection cycle” message
can be seen in the error log.

Syntax:

keepalive_disable none | browser ...;

Default:

keepalive_disable msie6;

Context:

http, server, location

Disables keep-alive connections with misbehaving browsers.
The browser parameters specify which
browsers will be affected.
The value msie6 disables keep-alive connections
with old versions of MSIE, once a POST request is received.
The value safari disables keep-alive connections
with Safari and Safari-like browsers on macOS and macOS-like
operating systems.
The value none enables keep-alive connections
with all browsers.

Prior to version 1.1.18, the value safari matched
all Safari and Safari-like browsers on all operating systems, and
keep-alive connections with them were disabled by default.

Syntax:

keepalive_min_timeout timeout;

Default:

keepalive_min_timeout 0;

Context:

http, server, location

This directive appeared in version 1.27.4.

Sets a timeout during which a keep-alive
client connection will not be closed on the server side
for connection reuse or on graceful shutdown of worker processes.

Syntax:

keepalive_requests number;

Default:

keepalive_requests 1000;

Context:

http, server, location

This directive appeared in version 0.8.0.

Sets the maximum number of requests that can be
served through one keep-alive connection.
After the maximum number of requests are made, the connection is closed.

Closing connections periodically is necessary to free
per-connection memory allocations.
Therefore, using too high maximum number of requests
could result in excessive memory usage and not recommended.

Prior to version 1.19.10, the default value was 100.

Syntax:

keepalive_time time;

Default:

keepalive_time 1h;

Context:

http, server, location

This directive appeared in version 1.19.10.

Limits the maximum time during which
requests can be processed through one keep-alive connection.
After this time is reached, the connection is closed
following the subsequent request processing.

Syntax:

keepalive_timeout
timeout
[header_timeout];

Default:

keepalive_timeout 75s;

Context:

http, server, location

The first parameter sets a timeout during which a keep-alive
client connection will stay open on the server side.
The zero value disables keep-alive client connections.
The optional second parameter sets a value in the
“Keep-Alive: timeout=time”
response header field.
Two parameters may differ.

The
“Keep-Alive: timeout=time”
header field is recognized by Mozilla and Konqueror.
MSIE closes keep-alive connections by itself in about 60 seconds.

Syntax:

large_client_header_buffers number size;

Default:

large_client_header_buffers 4 8k;

Context:

http, server

Sets the maximum number and size of
buffers used for reading large client request header.
A request line cannot exceed the size of one buffer, or the
414 (Request-URI Too Large)
error is returned to the client.
A request header field cannot exceed the size of one buffer as well, or the
400 (Bad Request)
error is returned to the client.
Buffers are allocated only on demand.
By default, the buffer size is equal to 8K bytes.
If after the end of request processing a connection is transitioned
into the keep-alive state, these buffers are released.

If the directive is specified on the server level,
the value from the default server can be used.
Details are provided in the
“Virtual
server selection” section.

Syntax:

limit_except method ... { ... }

Default:

—

Context:

location

Limits allowed HTTP methods inside a location.
The method parameter can be one of the following:
GET,
HEAD,
POST,
PUT,
DELETE,
MKCOL,
COPY,
MOVE,
OPTIONS,
PROPFIND,
PROPPATCH,
LOCK,
UNLOCK,
or
PATCH.
Allowing the GET method makes the
HEAD method also allowed.
Access to other methods can be limited using the
ngx_http_access_module,
ngx_http_auth_basic_module,
and
ngx_http_auth_jwt_module
(1.13.10)
modules directives:

limit_except GET {
allow 192.168.1.0/32;
deny all;
}

Please note that this will limit access to all methods
except GET and HEAD.

Syntax:

limit_rate rate;

Default:

limit_rate 0;

Context:

http, server, location, if in location

Limits the rate of response transmission to a client.
The rate is specified in bytes per second.
The zero value disables rate limiting.

The limit is set per a request, and so if a client simultaneously opens
two connections, the overall rate will be twice as much
as the specified limit.

Parameter value can contain variables (1.17.0).
It may be useful in cases where rate should be limited
depending on a certain condition:

map $slow $rate {
1 4k;
2 8k;
}

limit_rate $rate;

Rate limit can also be set in the
$limit_rate variable,
however, since version 1.17.0, this method is not recommended:

server {

if ($slow) {
set $limit_rate 4k;
}

...
}

Rate limit can also be set in the
“X-Accel-Limit-Rate” header field of a proxied server response.
This capability can be disabled using the
proxy_ignore_headers,
fastcgi_ignore_headers,
uwsgi_ignore_headers,
and
scgi_ignore_headers
directives.

Syntax:

limit_rate_after size;

Default:

limit_rate_after 0;

Context:

http, server, location, if in location

This directive appeared in version 0.8.0.

Sets the initial amount after which the further transmission
of a response to a client will be rate limited.
Parameter value can contain variables (1.17.0).

Example:

location /flv/ {
flv;
limit_rate_after 500k;
limit_rate 50k;
}

Syntax:

lingering_close
off |
on |
always;

Default:

lingering_close on;

Context:

http, server, location

This directive appeared in versions 1.1.0 and 1.0.6.

Controls how nginx closes client connections.

The default value “on” instructs nginx to
wait for and
process additional data from a client
before fully closing a connection, but only
if heuristics suggests that a client may be sending more data.

The value “always” will cause nginx to unconditionally
wait for and process additional client data.

The value “off” tells nginx to never wait for
more data and close the connection immediately.
This behavior breaks the protocol and should not be used under normal
circumstances.

To control closing
HTTP/2 connections,
the directive must be specified on the server level (1.19.1).

Syntax:

lingering_time time;

Default:

lingering_time 30s;

Context:

http, server, location

When lingering_close is in effect,
this directive specifies the maximum time during which nginx
will process (read and ignore) additional data coming from a client.
After that, the connection will be closed, even if there will be
more data.

Syntax:

lingering_timeout time;

Default:

lingering_timeout 5s;

Context:

http, server, location

When lingering_close is in effect, this directive specifies
the maximum waiting time for more client data to arrive.
If data are not received during this time, the connection is closed.
Otherwise, the data are read and ignored, and nginx starts waiting
for more data again.
The “wait-read-ignore” cycle is repeated, but no longer than specified by the
lingering_time directive.

Syntax:

listen
address[:port]
[default_server]
[ssl]
[http2 |
quic]
[proxy_protocol]
[setfib=number]
[fastopen=number]
[backlog=number]
[rcvbuf=size]
[sndbuf=size]
[accept_filter=filter]
[deferred]
[bind]
[ipv6only=on|off]
[reuseport]
[multipath]
[so_keepalive=on|off|[keepidle]:[keepintvl]:[keepcnt]];
listen
port
[default_server]
[ssl]
[http2 |
quic]
[proxy_protocol]
[setfib=number]
[fastopen=number]
[backlog=number]
[rcvbuf=size]
[sndbuf=size]
[accept_filter=filter]
[deferred]
[bind]
[ipv6only=on|off]
[reuseport]
[multipath]
[so_keepalive=on|off|[keepidle]:[keepintvl]:[keepcnt]];
listen
unix:path
[default_server]
[ssl]
[http2 |
quic]
[proxy_protocol]
[backlog=number]
[rcvbuf=size]
[sndbuf=size]
[accept_filter=filter]
[deferred]
[bind]
[so_keepalive=on|off|[keepidle]:[keepintvl]:[keepcnt]];

Default:

listen *:80 | *:8000;

Context:

server

Sets the address and port for IP,
or the path for a UNIX-domain socket on which
the server will accept requests.
Both address and port,
or only address or only port can be specified.
An address may also be a hostname, for example:

listen 127.0.0.1:8000;
listen 127.0.0.1;
listen 8000;
listen *:8000;
listen localhost:8000;

IPv6 addresses (0.7.36) are specified in square brackets:

listen [::]:8000;
listen [::1];

UNIX-domain sockets (0.8.21) are specified with the “unix:”
prefix:

listen unix:/var/run/nginx.sock;

If only address is given, the port 80 is used.

If the directive is not present then either *:80 is used
if nginx runs with the superuser privileges, or *:8000
otherwise.

The default_server parameter, if present,
will cause the server to become the default server for the specified
address:port pair.
If none of the directives have the default_server
parameter then the first server with the
address:port pair will be
the default server for this pair.

In versions prior to 0.8.21 this parameter is named simply
default.

The ssl parameter (0.7.14) allows specifying that all
connections accepted on this port should work in SSL mode.
This allows for a more compact configuration for the server that
handles both HTTP and HTTPS requests.

The http2 parameter (1.9.5) configures the port to accept
HTTP/2 connections.
Normally, for this to work the ssl parameter should be
specified as well, but nginx can also be configured to accept HTTP/2
connections without SSL.

The parameter is deprecated,
the http2 directive
should be used instead.

The quic parameter (1.25.0) configures the port to accept
QUIC connections.

The proxy_protocol parameter (1.5.12)
allows specifying that all connections accepted on this port should use the
PROXY
protocol.

The PROXY protocol version 2 is supported since version 1.13.11.

The listen directive
can have several additional parameters specific to socket-related system calls.
These parameters can be specified in any
listen directive, but only once for a given
address:port pair.

In versions prior to 0.8.21, they could only be
specified in the listen directive together with the
default parameter.

setfib=number

this parameter (0.8.44) sets the associated routing table, FIB
(the SO_SETFIB option) for the listening socket.
This currently works only on FreeBSD.

fastopen=number

enables
“TCP Fast Open”
for the listening socket (1.5.8) and
limits
the maximum length for the queue of connections that have not yet completed
the three-way handshake.

Do not enable this feature unless the server can handle
receiving the

same SYN packet with data more than once.

backlog=number

sets the backlog parameter in the
listen() call that limits
the maximum length for the queue of pending connections.
By default,
backlog is set to -1 on FreeBSD, DragonFly BSD, and macOS,
and to 511 on other platforms.

rcvbuf=size

sets the receive buffer size
(the SO_RCVBUF option) for the listening socket.

sndbuf=size

sets the send buffer size
(the SO_SNDBUF option) for the listening socket.

accept_filter=filter

sets the name of accept filter
(the SO_ACCEPTFILTER option) for the listening socket
that filters incoming connections before passing them to
accept().
This works only on FreeBSD and NetBSD 5.0+.
Possible values are
dataready
and
httpready.

deferred

instructs to use a deferred accept()
(the TCP_DEFER_ACCEPT socket option) on Linux.

bind

instructs to make a separate bind() call for a given
address:port pair.
This is useful because if there are several listen
directives with the same port but different addresses, and one of the
listen directives listens on all addresses
for the given port (*:port), nginx
will bind() only to *:port.
It should be noted that the getsockname() system call will be
made in this case to determine the address that accepted the connection.
If the setfib,
fastopen,
backlog, rcvbuf,
sndbuf, accept_filter,
deferred, ipv6only,
reuseport, multipath,
or so_keepalive parameters
are used then for a given
address:port pair
a separate bind() call will always be made.

ipv6only=on|off

this parameter (0.7.42) determines
(via the IPV6_V6ONLY socket option)
whether an IPv6 socket listening on a wildcard address [::]
will accept only IPv6 connections or both IPv6 and IPv4 connections.
This parameter is turned on by default.
It can only be set once on start.

Prior to version 1.3.4,
if this parameter was omitted then the operating system’s settings were
in effect for the socket.

reuseport

this parameter (1.9.1) instructs to create an individual listening socket
for each worker process
(using the
SO_REUSEPORT socket option on Linux 3.9+ and DragonFly BSD,
or SO_REUSEPORT_LB on FreeBSD 12+), allowing a kernel
to distribute incoming connections between worker processes.
This currently works only on Linux 3.9+, DragonFly BSD,
and FreeBSD 12+ (1.15.1).

Inappropriate use of this option may have its security
implications.

multipath

this parameter (1.29.7) configures the
Multipath TCP
protocol (IPPROTO_MPTCP) for the listening socket.
This currently works only on Linux 5.6+.

Adding or removing this parameter will also enable
the SO_REUSEPORT socket option, which may have its security
implications.

so_keepalive=on|off|[keepidle]:[keepintvl]:[keepcnt]

this parameter (1.1.11) configures the “TCP keepalive” behavior
for the listening socket.
If this parameter is omitted then the operating system’s settings will be
in effect for the socket.
If it is set to the value “on”, the
SO_KEEPALIVE option is turned on for the socket.
If it is set to the value “off”, the
SO_KEEPALIVE option is turned off for the socket.
Some operating systems support setting of TCP keepalive parameters on
a per-socket basis using the TCP_KEEPIDLE,
TCP_KEEPINTVL, and TCP_KEEPCNT socket options.
On such systems
(currently, Linux, NetBSD, Dragonfly, FreeBSD, and macOS),
they can be configured
using the keepidle, keepintvl, and
keepcnt parameters.
One or two parameters may be omitted, in which case the system default setting
for the corresponding socket option will be in effect.
For example,

so_keepalive=30m::10

will set the idle timeout (TCP_KEEPIDLE) to 30 minutes,
leave the probe interval (TCP_KEEPINTVL) at its system default,
and set the probes count (TCP_KEEPCNT) to 10 probes.

Example:

listen 127.0.0.1 default_server accept_filter=dataready backlog=1024;

Syntax:

location [
= |
~ |
~* |
^~
] uri { ... }
location @name { ... }

Default:

—

Context:

server, location

Sets configuration depending on a request URI.

The matching is performed against a normalized URI,
after decoding the text encoded in the “%XX” form,
resolving references to relative path components “.”
and “..”, and possible
compression of two or more
adjacent slashes into a single slash.

A location can either be defined by a prefix string, or by a regular expression.
Regular expressions are specified with the preceding
“~*” modifier (for case-insensitive matching), or the
“~” modifier (for case-sensitive matching).
To find location matching a given request, nginx first checks
locations defined using the prefix strings (prefix locations).
Among them, the location with the longest matching
prefix is selected and remembered.
Then regular expressions are checked, in the order of their appearance
in the configuration file.
The search of regular expressions terminates on the first match,
and the corresponding configuration is used.
If no match with a regular expression is found then the
configuration of the prefix location remembered earlier is used.

location blocks can be nested, with some exceptions
mentioned below.

For case-insensitive operating systems such as macOS and Cygwin,
matching with prefix strings ignores a case (0.7.7).
However, comparison is limited to one-byte locales.

Regular expressions can contain captures (0.7.40) that can later
be used in other directives.

If the longest matching prefix location has the “^~” modifier
then regular expressions are not checked.

Also, using the “=” modifier it is possible to define
an exact match of URI and location.
If an exact match is found, the search terminates.
For example, if a “/” request happens frequently,
defining “location = /” will speed up the processing
of these requests, as search terminates right after the first
comparison.
Such a location cannot obviously contain nested locations.

In versions from 0.7.1 to 0.8.41, if a request matched the prefix
location without the “=” and “^~”
modifiers, the search also terminated and regular expressions were
not checked.

Let’s illustrate the above by an example:

location = / {
[ configuration A ]
}

location / {
[ configuration B ]
}

location /documents/ {
[ configuration C ]
}

location ^~ /images/ {
[ configuration D ]
}

location ~* \.(gif|jpg|jpeg)$ {
[ configuration E ]
}

The “/” request will match configuration A,
the “/index.html” request will match configuration B,
the “/documents/document.html” request will match
configuration C,
the “/images/1.gif” request will match configuration D, and
the “/documents/1.jpg” request will match configuration E.

The “@” prefix defines a named location.
Such a location is not used for a regular request processing, but instead
used for request redirection.
They cannot be nested, and cannot contain nested locations.

If a location is defined by a prefix string that ends with the slash character,
and requests are processed by one of
proxy_pass,
fastcgi_pass,
uwsgi_pass,
scgi_pass,
memcached_pass, or
grpc_pass,
then the special processing is performed.
In response to a request with URI equal to this string,
but without the trailing slash,
a permanent redirect with the code 301 will be returned to the requested URI
with the slash appended.
If this is not desired, an exact match of the URI and location could be
defined like this:

location /user/ {
proxy_pass http://user.example.com;
}

location = /user {
proxy_pass http://login.example.com;
}

Syntax:

log_not_found on | off;

Default:

log_not_found on;

Context:

http, server, location

Enables or disables logging of errors about not found files into
error_log.

Syntax:

log_subrequest on | off;

Default:

log_subrequest off;

Context:

http, server, location

Enables or disables logging of subrequests into
access_log.

Syntax:

max_headers number;

Default:

max_headers 1000;

Context:

http, server

This directive appeared in version 1.29.8.

Sets the maximum allowed number of header lines in requests.
If this limit is reached, the error
400 (Bad Request)
is returned.

Syntax:

max_ranges number;

Default:

—

Context:

http, server, location

This directive appeared in version 1.1.2.

Limits the maximum allowed number of ranges in byte-range requests.
Requests that exceed the limit are processed as if there were no
byte ranges specified.
By default, the number of ranges is not limited.
The zero value disables the byte-range support completely.

Syntax:

merge_slashes on | off;

Default:

merge_slashes on;

Context:

http, server

Enables or disables compression of two or more adjacent slashes
in a URI into a single slash.

Note that compression is essential for the correct matching of prefix string
and regular expression locations.
Without it, the “//scripts/one.php” request would not match

location /scripts/ {
...
}

and might be processed as a static file.
So it gets converted to “/scripts/one.php”.

Turning the compression off can become necessary if a URI
contains base64-encoded names, since base64 uses the “/”
character internally.
However, for security considerations, it is better to avoid turning
the compression off.

If the directive is specified on the server level,
the value from the default server can be used.
Details are provided in the
“Virtual
server selection” section.

Syntax:

msie_padding on | off;

Default:

msie_padding on;

Context:

http, server, location

Enables or disables adding comments to responses for MSIE clients with status
greater than 400 to increase the response size to 512 bytes.

Syntax:

msie_refresh on | off;

Default:

msie_refresh off;

Context:

http, server, location

Enables or disables issuing refreshes instead of redirects for MSIE clients.

Syntax:

open_file_cache off;
open_file_cache
max=N
[inactive=time];

Default:

open_file_cache off;

Context:

http, server, location

Configures a cache that can store:

open file descriptors, their sizes and modification times;

information on existence of directories;

file lookup errors, such as “file not found”, “no read permission”,
and so on.

Caching of errors should be enabled separately by the
open_file_cache_errors
directive.

The directive has the following parameters:

max

sets the maximum number of elements in the cache;
on cache overflow the least recently used (LRU) elements are removed;

inactive

defines a time after which an element is removed from the cache
if it has not been accessed during this time;
by default, it is 60 seconds;

off

disables the cache.

Example:

open_file_cache max=1000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;

Syntax:

open_file_cache_errors on | off;

Default:

open_file_cache_errors off;

Context:

http, server, location

Enables or disables caching of file lookup errors by
open_file_cache.

Syntax:

open_file_cache_min_uses number;

Default:

open_file_cache_min_uses 1;

Context:

http, server, location

Sets the minimum number of file accesses during
the period configured by the inactive parameter
of the open_file_cache directive, required for a file
descriptor to remain open in the cache.

Syntax:

open_file_cache_valid time;

Default:

open_file_cache_valid 60s;

Context:

http, server, location

Sets a time after which
open_file_cache
elements should be validated.

Syntax:

output_buffers number size;

Default:

output_buffers 2 32k;

Context:

http, server, location

Sets the number and size of the
buffers used for reading a response from a disk.

Prior to version 1.9.5, the default value was 1 32k.

Syntax:

port_in_redirect on | off;

Default:

port_in_redirect on;

Context:

http, server, location

Enables or disables specifying the port in
absolute redirects issued by nginx.

The use of the primary server name in redirects is controlled by
the server_name_in_redirect directive.

Syntax:

postpone_output size;

Default:

postpone_output 1460;

Context:

http, server, location

If possible, the transmission of client data will be postponed until
nginx has at least size bytes of data to send.
The zero value disables postponing data transmission.

Syntax:

read_ahead size;

Default:

read_ahead 0;

Context:

http, server, location

Sets the amount of pre-reading for the kernel when working with file.

On Linux, the
posix_fadvise(0, 0, 0, POSIX_FADV_SEQUENTIAL)
system call is used, and so the size parameter is ignored.

On FreeBSD, the
fcntl(O_READAHEAD,
size)
system call, supported since FreeBSD 9.0-CURRENT, is used.
FreeBSD 7 has to be
patched.

Syntax:

recursive_error_pages on | off;

Default:

recursive_error_pages off;

Context:

http, server, location

Enables or disables doing several redirects using the
error_page
directive.
The number of such redirects is limited.

Syntax:

request_pool_size size;

Default:

request_pool_size 4k;

Context:

http, server

Allows accurate tuning of per-request memory allocations.
This directive has minimal impact on performance
and should not generally be used.

Syntax:

reset_timedout_connection on | off;

Default:

reset_timedout_connection off;

Context:

http, server, location

Enables or disables resetting timed out connections
and connections
closed
with the non-standard code 444 (1.15.2).
The reset is performed as follows.
Before closing a socket, the
SO_LINGER
option is set on it with a timeout value of 0.
When the socket is closed, TCP RST is sent to the client, and all memory
occupied by this socket is released.
This helps avoid keeping an already closed socket with filled buffers
in a FIN_WAIT1 state for a long time.

It should be noted that timed out keep-alive connections are
closed normally.

Syntax:

resolver
address ...
[valid=time]
[ipv4=on|off]
[ipv6=on|off]
[status_zone=zone];

Default:

—

Context:

http, server, location

Configures name servers used to resolve names of upstream servers
into addresses, for example:

resolver 127.0.0.1 [::1]:5353;

The address can be specified as a domain name or IP address,
with an optional port (1.3.1, 1.2.2).
If port is not specified, the port 53 is used.
Name servers are queried in a round-robin fashion.

Before version 1.1.7, only a single name server could be configured.
Specifying name servers using IPv6 addresses is supported
starting from versions 1.3.1 and 1.2.2.

By default, nginx will look up both IPv4 and IPv6 addresses while resolving.
If looking up of IPv4 or IPv6 addresses is not desired,
the ipv4=off (1.23.1) or
the ipv6=off parameter can be specified.

Resolving of names into IPv6 addresses is supported
starting from version 1.5.8.

By default, nginx caches answers using the TTL value of a response.
An optional valid parameter allows overriding it:

resolver 127.0.0.1 [::1]:5353 valid=30s;

Before version 1.1.9, tuning of caching time was not possible,
and nginx always cached answers for the duration of 5 minutes.

To prevent DNS spoofing, it is recommended
configuring DNS servers in a properly secured trusted local network.

The optional status_zone parameter (1.17.1)
enables
collection
of DNS server statistics of requests and responses
in the specified zone.
The parameter is available as part of our
commercial subscription.

Syntax:

resolver_timeout time;

Default:

resolver_timeout 30s;

Context:

http, server, location

Sets a timeout for name resolution, for example:

resolver_timeout 5s;

Syntax:

root path;

Default:

root html;

Context:

http, server, location, if in location

Sets the root directory for requests.
For example, with the following configuration

location /i/ {
root /data/w3;
}

The /data/w3/i/top.gif file will be sent in response to
the “/i/top.gif” request.

The path value can contain variables,
except $document_root and $realpath_root.

A path to the file is constructed by merely adding a URI to the value
of the root directive.
If a URI has to be modified, the
alias directive should be used.

Syntax:

satisfy all | any;

Default:

satisfy all;

Context:

http, server, location

Allows access if all (all) or at least one
(any) of the
ngx_http_access_module,
ngx_http_auth_basic_module,
ngx_http_auth_request_module,
ngx_http_auth_jwt_module
(1.13.10),
or
ngx_http_auth_oidc_module
(1.27.4)
modules allow access.

Example:

location / {
satisfy any;

allow 192.168.1.0/32;
deny all;

auth_basic "closed site";
auth_basic_user_file conf/htpasswd;
}

Syntax:

send_lowat size;

Default:

send_lowat 0;

Context:

http, server, location

If the directive is set to a non-zero value, nginx will try to minimize
the number of send operations on client sockets by using either
NOTE_LOWAT flag of the
kqueue method
or the SO_SNDLOWAT socket option.
In both cases the specified size is used.

This directive is ignored on Linux, Solaris, and Windows.

Syntax:

send_timeout time;

Default:

send_timeout 60s;

Context:

http, server, location

Sets a timeout for transmitting a response to the client.
The timeout is set only between two successive write operations,
not for the transmission of the whole response.
If the client does not receive anything within this time,
the connection is closed.

Syntax:

sendfile on | off;

Default:

sendfile off;

Context:

http, server, location, if in location

Enables or disables the use of
sendfile().

Starting from nginx 0.8.12 and FreeBSD 5.2.1,
aio can be used to pre-load data
for sendfile():

location /video/ {
sendfile on;
tcp_nopush on;
aio on;
}

In this configuration, sendfile() is called with
the SF_NODISKIO flag which causes it not to block on disk I/O,
but, instead, report back that the data are not in memory.
nginx then initiates an asynchronous data load by reading one byte.
On the first read, the FreeBSD kernel loads the first 128K bytes
of a file into memory, although next reads will only load data in 16K chunks.
This can be changed using the
read_ahead directive.

Before version 1.7.11, pre-loading could be enabled with
aio sendfile;.

Syntax:

sendfile_max_chunk size;

Default:

sendfile_max_chunk 2m;

Context:

http, server, location

Limits the amount of data that can be
transferred in a single sendfile() call.
Without the limit, one fast connection may seize the worker process entirely.

Prior to version 1.21.4, by default there was no limit.

Syntax:

server { ... }

Default:

—

Context:

http

Sets configuration for a virtual server.
There is no clear separation between IP-based (based on the IP address)
and name-based (based on the “Host” request header field)
virtual servers.
Instead, the listen directives describe all
addresses and ports that should accept connections for the server, and the
server_name directive lists all server names.
Example configurations are provided in the
“How nginx processes a request” document.

Syntax:

server_name name ...;

Default:

server_name "";

Context:

server

Sets names of a virtual server, for example:

server {
server_name example.com www.example.com;
}

The first name becomes the primary server name.

Server names can include an asterisk (“*”)
replacing the first or last part of a name:

server {
server_name example.com *.example.com www.example.*;
}

Such names are called wildcard names.

The first two of the names mentioned above can be combined in one:

server {
server_name .example.com;
}

It is also possible to use regular expressions in server names,
preceding the name with a tilde (“~”):

server {
server_name www.example.com ~^www\d+\.example\.com$;
}

Regular expressions can contain captures (0.7.40) that can later
be used in other directives:

server {
server_name ~^(www\.)?(.+)$;

location / {
root /sites/$2;
}
}

server {
server_name _;

location / {
root /sites/default;
}
}

Named captures in regular expressions create variables (0.8.25)
that can later be used in other directives:

server {
server_name ~^(www\.)?(?<domain>.+)$;

location / {
root /sites/$domain;
}
}

server {
server_name _;

location / {
root /sites/default;
}
}

If the directive’s parameter is set to “$hostname” (0.9.4), the
machine’s hostname is inserted.

It is also possible to specify an empty server name (0.7.11):

server {
server_name www.example.com "";
}

It allows this server to process requests without the “Host”
header field — instead of the default server — for the given address:port pair.
This is the default setting.

Before 0.8.48, the machine’s hostname was used by default.

The search is performed in the following order of priority
and terminates on the first matching variant:

the exact name

the longest wildcard name starting with an asterisk,
e.g. “*.example.com”

the longest wildcard name ending with an asterisk,
e.g. “mail.*”

the first matching regular expression
(in order of appearance in the configuration file)

Detailed description of server names is provided in a separate
Server names document.

Syntax:

server_name_in_redirect on | off;

Default:

server_name_in_redirect off;

Context:

http, server, location

Enables or disables the use of the primary server name, specified by the
server_name directive,
in absolute redirects issued by nginx.
When the use of the primary server name is disabled, the name from the
“Host” request header field is used.
If this field is not present, the IP address of the server is used.

The use of a port in redirects is controlled by
the port_in_redirect directive.

Syntax:

server_names_hash_bucket_size size;

Default:

server_names_hash_bucket_size 32|64|128;

Context:

http

Sets the bucket size for the server names hash tables.
The default value depends on the size of the processor’s cache line.
The details of setting up hash tables are provided in a separate
document.

Syntax:

server_names_hash_max_size size;

Default:

server_names_hash_max_size 512;

Context:

http

Sets the maximum size of the server names hash tables.
The details of setting up hash tables are provided in a separate
document.

Syntax:

server_tokens
on |
off |
build |
string;

Default:

server_tokens on;

Context:

http, server, location

Enables or disables emitting nginx version on error pages and in the
“Server” response header field.

The build parameter (1.11.10) enables emitting
a build name
along with nginx version.

Additionally, as part of our
commercial subscription,
starting from version 1.9.13
the signature on error pages and
the “Server” response header field value
can be set explicitly using the string with variables.
An empty string disables the emission of the “Server” field.

Syntax:

subrequest_output_buffer_size size;

Default:

subrequest_output_buffer_size 4k|8k;

Context:

http, server, location

This directive appeared in version 1.13.10.

Sets the size of the buffer used for
storing the response body of a subrequest.
By default, the buffer size is equal to one memory page.
This is either 4K or 8K, depending on a platform.
It can be made smaller, however.

The directive is applicable only for subrequests
with response bodies saved into memory.
For example, such subrequests are created by
SSI.

Syntax:

tcp_nodelay on | off;

Default:

tcp_nodelay on;

Context:

http, server, location

Enables or disables the use of the TCP_NODELAY option.
The option is enabled when a connection is transitioned into the
keep-alive state.
Additionally, it is enabled on SSL connections,
for unbuffered proxying,
and for WebSocket proxying.

Syntax:

tcp_nopush on | off;

Default:

tcp_nopush off;

Context:

http, server, location

Enables or disables the use of
the TCP_NOPUSH socket option on FreeBSD
or the TCP_CORK socket option on Linux.
The options are enabled only when sendfile is used.
Enabling the option allows

sending the response header and the beginning of a file in one packet,
on Linux and FreeBSD 4.*;

sending a file in full packets.

Syntax:

try_files file ... uri;
try_files file ... =code;

Default:

—

Context:

server, location

Checks the existence of files in the specified order and uses
the first found file for request processing; the processing
is performed in the current context.
The path to a file is constructed from the
file parameter
according to the
root and alias directives.
It is possible to check directory’s existence by specifying
a slash at the end of a name, e.g. “$uri/”.
If none of the files were found, an internal redirect to the
uri specified in the last parameter is made.
For example:

location /images/ {
try_files $uri /images/default.gif;
}

location = /images/default.gif {
expires 30s;
}

The last parameter can also point to a named location,
as shown in examples below.
Starting from version 0.7.51, the last parameter can also be a
code:

location / {
try_files $uri $uri/index.html $uri.html =404;
}

Example in proxying Mongrel:

location / {
try_files /system/maintenance.html
$uri $uri/index.html $uri.html
@mongrel;
}

location @mongrel {
proxy_pass http://mongrel;
}

Example for Drupal/FastCGI:

location / {
try_files $uri $uri/ @drupal;
}

location ~ \.php$ {
try_files $uri @drupal;

fastcgi_pass ...;

fastcgi_param SCRIPT_FILENAME /path/to$fastcgi_script_name;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param QUERY_STRING $args;

... other fastcgi_param's
}

location @drupal {
fastcgi_pass ...;

fastcgi_param SCRIPT_FILENAME /path/to/index.php;
fastcgi_param SCRIPT_NAME /index.php;
fastcgi_param QUERY_STRING q=$uri&$args;

... other fastcgi_param's
}

In the following example,

location / {
try_files $uri $uri/ @drupal;
}

the try_files directive is equivalent to

location / {
error_page 404 = @drupal;
log_not_found off;
}

And here,

location ~ \.php$ {
try_files $uri @drupal;

fastcgi_pass ...;

fastcgi_param SCRIPT_FILENAME /path/to$fastcgi_script_name;

...
}

try_files checks the existence of the PHP file
before passing the request to the FastCGI server.

Example for Wordpress and Joomla:

location / {
try_files $uri $uri/ @wordpress;
}

location ~ \.php$ {
try_files $uri @wordpress;

fastcgi_pass ...;

fastcgi_param SCRIPT_FILENAME /path/to$fastcgi_script_name;
... other fastcgi_param's
}

location @wordpress {
fastcgi_pass ...;

fastcgi_param SCRIPT_FILENAME /path/to/index.php;
... other fastcgi_param's
}

Syntax:

types { ... }

Default:

types {
text/html html;
image/gif gif;
image/jpeg jpg;
}

Context:

http, server, location

Maps file name extensions to MIME types of responses.
Extensions are case-insensitive.
Several extensions can be mapped to one type, for example:

types {
application/octet-stream bin exe dll;
application/octet-stream deb;
application/octet-stream dmg;
}

A sufficiently full mapping table is distributed with nginx in the
conf/mime.types file.

To make a particular location emit the
“application/octet-stream”
MIME type for all requests, the following configuration can be used:

location /download/ {
types { }
default_type application/octet-stream;
}

Syntax:

types_hash_bucket_size size;

Default:

types_hash_bucket_size 64;

Context:

http, server, location

Sets the bucket size for the types hash tables.
The details of setting up hash tables are provided in a separate
document.

Prior to version 1.5.13,
the default value depended on the size of the processor’s cache line.

Syntax:

types_hash_max_size size;

Default:

types_hash_max_size 1024;

Context:

http, server, location

Sets the maximum size of the types hash tables.
The details of setting up hash tables are provided in a separate
document.

Syntax:

underscores_in_headers on | off;

Default:

underscores_in_headers off;

Context:

http, server

Enables or disables the use of underscores in client request header fields.
When the use of underscores is disabled, request header fields whose names
contain underscores are
marked as invalid and become subject to the
ignore_invalid_headers directive.

If the directive is specified on the server level,
the value from the default server can be used.
Details are provided in the
“Virtual
server selection” section.

Syntax:

variables_hash_bucket_size size;

Default:

variables_hash_bucket_size 64;

Context:

http

Sets the bucket size for the variables hash table.
The details of setting up hash tables are provided in a separate
document.

Syntax:

variables_hash_max_size size;

Default:

variables_hash_max_size 1024;

Context:

http

Sets the maximum size of the variables hash table.
The details of setting up hash tables are provided in a separate
document.

Prior to version 1.5.13, the default value was 512.

Embedded Variables

The ngx_http_core_module module supports embedded variables
with names matching the Apache Server variables.
First of all, these are variables representing client request header
fields, such as $http_user_agent, $http_cookie,
and so on.
Also there are other variables:

$arg_name

argument name in the request line

$args

arguments in the request line

$binary_remote_addr

client address in a binary form, value’s length is always 4 bytes
for IPv4 addresses or 16 bytes for IPv6 addresses

$body_bytes_sent

number of bytes sent to a client, not counting the response header;
this variable is compatible with the “%B” parameter of the
mod_log_config
Apache module

$bytes_sent

number of bytes sent to a client (1.3.8, 1.2.5)

$connection

connection serial number (1.3.8, 1.2.5)

$connection_requests

current number of requests made through a connection (1.3.8, 1.2.5)

$connection_time

connection time in seconds with a milliseconds resolution (1.19.10)

$content_length

“Content-Length” request header field

$content_type

“Content-Type” request header field

$cookie_name

the name cookie

$document_root

root or alias directive’s value
for the current request

$document_uri

same as $uri

$host

in this order of precedence:
host name from the request line, or
host name from the “Host” request header field, or
the server name matching a request

$hostname

host name

$http_name

arbitrary request header field;
the last part of a variable name is the field name converted
to lower case with dashes replaced by underscores

$https

“on”
if connection operates in SSL mode,
or an empty string otherwise

$is_args

“?” if a request line has arguments,
or an empty string otherwise

$is_request_port

“:” if
$request_port is non-empty,
or an empty string otherwise (1.29.3)

$limit_rate

setting this variable enables response rate limiting;
see limit_rate

$msec

current time in seconds with the milliseconds resolution (1.3.9, 1.2.6)

$nginx_version

nginx version

$pid

PID of the worker process

$pipe

“p” if request was pipelined, “.”
otherwise (1.3.12, 1.2.7)

$proxy_protocol_addr

client address from the PROXY protocol header (1.5.12)

The PROXY protocol must be previously enabled by setting the
proxy_protocol parameter
in the listen directive.

$proxy_protocol_port

client port from the PROXY protocol header (1.11.0)

The PROXY protocol must be previously enabled by setting the
proxy_protocol parameter
in the listen directive.

$proxy_protocol_server_addr

server address from the PROXY protocol header (1.17.6)

The PROXY protocol must be previously enabled by setting the
proxy_protocol parameter
in the listen directive.

$proxy_protocol_server_port

server port from the PROXY protocol header (1.17.6)

The PROXY protocol must be previously enabled by setting the
proxy_protocol parameter
in the listen directive.

$proxy_protocol_tlv_name

TLV from the PROXY Protocol header (1.23.2).
The name can be a TLV type name or its numeric value.
In the latter case, the value is hexadecimal
and should be prefixed with 0x:

$proxy_protocol_tlv_alpn
$proxy_protocol_tlv_0x01

SSL TLVs can also be accessed by TLV type name
or its numeric value,
both prefixed by ssl_:

$proxy_protocol_tlv_ssl_version
$proxy_protocol_tlv_ssl_0x21

The following TLV type names are supported:

alpn (0x01) -
upper layer protocol used over the connection

authority (0x02) -
host name value passed by the client

unique_id (0x05) -
unique connection id

netns (0x30) -
name of the namespace

ssl (0x20) -
binary SSL TLV structure

The following SSL TLV type names are supported:

ssl_version (0x21) -
SSL version used in client connection

ssl_cn (0x22) -
SSL certificate Common Name

ssl_cipher (0x23) -
name of the used cipher

ssl_sig_alg (0x24) -
algorithm used to sign the certificate

ssl_key_alg (0x25) -
public-key algorithm

Also, the following special SSL TLV type name is supported:

ssl_verify -
client SSL certificate verification result,
0 if the client presented a certificate
and it was successfully verified,
non-zero otherwise.

The PROXY protocol must be previously enabled by setting the
proxy_protocol parameter
in the listen directive.

$query_string

same as $args

$realpath_root

an absolute pathname corresponding to the
root or alias directive’s value
for the current request,
with all symbolic links resolved to real paths

$remote_addr

client address

$remote_port

client port

$remote_user

user name supplied with the Basic authentication

$request

full original request line

$request_body

request body

The variable’s value is made available in locations
processed by the
proxy_pass,
fastcgi_pass,
uwsgi_pass,
and
scgi_pass
directives when the request body was read to
a memory buffer.

$request_body_file

name of a temporary file with the request body

At the end of processing, the file needs to be removed.
To always write the request body to a file,
client_body_in_file_only needs to be enabled.
When the name of a temporary file is passed in a proxied request
or in a request to a FastCGI/uwsgi/SCGI server,
passing the request body should be disabled by the

proxy_pass_request_body off,

fastcgi_pass_request_body off,

uwsgi_pass_request_body off, or

scgi_pass_request_body off
directives, respectively.

$request_completion

“OK” if a request has completed,
or an empty string otherwise

$request_filename

file path for the current request, based on the
root or alias
directives, and the request URI

$request_id

unique request identifier
generated from 16 random bytes, in hexadecimal (1.11.0)

$request_length

request length (including request line, header, and request body)
(1.3.12, 1.2.7)

$request_method

request method, usually
“GET” or “POST”

$request_port

in this order of precedence:
port number from the
URI
authority component, or
port number from the “Host” request header field (1.29.3)

$request_time

request processing time in seconds with a milliseconds resolution
(1.3.9, 1.2.6);
time elapsed since the first bytes were read from the client

$request_uri

full original request URI (with arguments)

$scheme

request scheme, “http” or “https”

$sent_http_name

arbitrary response header field;
the last part of a variable name is the field name converted
to lower case with dashes replaced by underscores

$sent_trailer_name

arbitrary field sent at the end of the response (1.13.2);
the last part of a variable name is the field name converted
to lower case with dashes replaced by underscores

$server_addr

an address of the server which accepted a request

Computing a value of this variable usually requires one system call.
To avoid a system call, the listen directives
must specify addresses and use the bind parameter.

$server_name

name of the server which accepted a request

$server_port

port of the server which accepted a request

$server_protocol

request protocol, usually
“HTTP/1.0”,
“HTTP/1.1”,
“HTTP/2.0”,
or
“HTTP/3.0”

$status

response status (1.3.2, 1.2.2)

$tcpinfo_rtt,
$tcpinfo_rttvar,
$tcpinfo_snd_cwnd,
$tcpinfo_rcv_space

information about the client TCP connection; available on systems
that support the TCP_INFO socket option

$time_iso8601

local time in the ISO 8601 standard format (1.3.12, 1.2.7)

$time_iso8601_ms

local time in the ISO 8601 standard format
with a millisecond resolution (1.29.8)

This variable is available as part of our
commercial subscription.

$time_local

local time in the Common Log Format (1.3.12, 1.2.7)

$uri

current URI in request, normalized

The value of $uri may change during request processing,
e.g. when doing internal redirects, or when using index files.