Module ngx_stream_upstream_hc_module

Planning your ingress-nginx migration? Start here:
kubernetes.nginx.org.

english
русский
news
about
download
security
documentation
faq
books
community
enterprise
community forum (new)
x.com
blog
njs
ingress controller
gateway fabric

Module ngx_stream_upstream_hc_module

Example Configuration
Directives
health_check
health_check_timeout
match

The ngx_stream_upstream_hc_module module (1.9.0)
allows enabling periodic health checks of the servers in a
group.
The server group must reside in the
shared memory.

If a health check fails, the server will be considered unhealthy.
If several health checks are defined for the same group of servers,
a single failure of any check will make the corresponding server be
considered unhealthy.
Client connections are not passed to unhealthy servers
and servers in the “checking” state.

This module is available as part of our
commercial subscription.

Example Configuration

upstream tcp {
zone upstream_tcp 64k;

server backend1.example.com:12345 weight=5;
server backend2.example.com:12345 fail_timeout=5s slow_start=30s;
server 192.0.2.1:12345 max_fails=3;

server backup1.example.com:12345 backup;
server backup2.example.com:12345 backup;
}

server {
listen 12346;
proxy_pass tcp;
health_check;
}

With this configuration, nginx
will check the ability to establish a TCP connection to each server
in the tcp group every five seconds.
When a connection to the server cannot be established,
the health check will fail, and the server will
be considered unhealthy.

Health checks can be configured for the UDP protocol:

upstream dns_upstream {

zone dns_zone 64k;

server dns1.example.com:53;
server dns2.example.com:53;
server dns3.example.com:53;
}

server {
listen 53 udp;
proxy_pass dns_upstream;
health_check udp;
}

In this case, the absence of
ICMP “Destination Unreachable” message is expected
in reply to the sent string “nginx health check”.

Health checks can also be configured to test data obtained from the server.
Tests are configured separately using the match directive
and referenced in the match parameter
of the health_check directive.

Directives

Syntax:

health_check [parameters];

Default:

—

Context:

server

Enables periodic health checks of the servers in a
group.

The following optional parameters are supported:

interval=time

sets the interval between two consecutive health checks,
by default, 5 seconds.

jitter=time

sets the time within which
each health check will be randomly delayed,
by default, there is no delay.

fails=number

sets the number of consecutive failed health checks of a particular server
after which this server will be considered unhealthy,
by default, 1.

passes=number

sets the number of consecutive passed health checks of a particular server
after which the server will be considered healthy,
by default, 1.

mandatory [persistent]

sets the initial “checking” state for a server
until the first health check is completed (1.11.7).
Client connections are not passed to servers in the “checking” state.
If the parameter is not specified,
the server will be initially considered healthy.

The persistent parameter (1.21.1)
sets the initial “up” state for a server after reload
if the server was considered healthy before reload.

match=name

specifies the match block configuring the tests that a
successful connection should pass in order for a health check to pass.
By default, for TCP, only the ability
to establish a TCP connection with the server is checked.
For UDP, the absence of
ICMP “Destination Unreachable” message is expected
in reply to the sent string “nginx health check”.

Prior to version 1.11.7, by default, UDP health check
required a match block with the
send and expect
parameters.

port=number

defines the port used when connecting to a server
to perform a health check (1.9.7).
By default, equals the
server port.

udp

specifies that the UDP protocol should be used for
health checks instead of the default TCP protocol (1.9.13).

Syntax:

health_check_timeout timeout;

Default:

health_check_timeout 5s;

Context:

stream, server

Overrides the
proxy_timeout
value for health checks.

Syntax:

match name { ... }

Default:

—

Context:

stream

Defines the named test set used to verify server responses to health checks.

The following parameters can be configured:

send string;

sends a string to the server;

expect string |
~ regex;

a literal string (1.9.12) or a regular expression
that the data obtained from the server should match.
The regular expression is specified with the preceding
“~*” modifier (for case-insensitive matching), or the
“~” modifier (for case-sensitive matching).

Both send and expect parameters
can contain hexadecimal literals with the prefix “\x”
followed by two hex digits, for example, “\x80” (1.9.12).

Health check is passed if:

the TCP connection was successfully established;

the string from the send parameter,
if specified, was sent;

the data obtained from the server matched the string or regular expression
from the expect parameter, if specified;

the time elapsed does not exceed the value specified
in the health_check_timeout directive.

Example:

upstream backend {
zone upstream_backend 10m;
server 127.0.0.1:12345;
}

match http {
send "GET / HTTP/1.0\r\nHost: localhost\r\n\r\n";
expect ~ "200 OK";
}

server {
listen 12346;
proxy_pass backend;
health_check match=http;
}

Only the first
proxy_buffer_size
bytes of data obtained from the server are examined.