biomaj-download 3.2.12
BioMAJ download service
Requires Python: <4,>=3.6

# Biomaj-download

## About

[![PyPI version](https://badge.fury.io/py/biomaj-download.svg)](https://badge.fury.io/py/biomaj-download)

Microservice to manage the downloads of biomaj.

A protobuf interface is available in `biomaj_download/message/downmessage_pb2.py` to exchange messages between BioMAJ and the download service.
Messages go through RabbitMQ (to be installed).

Python3 support only, python2 support is dropped

## Protobuf

If you make changes to protobuf code, you need to compile it to python code:

```bash
cd /tmp/protoc/
PB_REL="https://github.com/protocolbuffers/protobuf/releases"
curl -LO $PB_REL/download/v23.2/protoc-23.2-linux-x86_64.zip  # Version used by GitHub Actions currently
unzip protoc-23.2-linux-x86_64.zip
cd ..../biomaj_download/message/
/tmp/protoc/bin/protoc --python_out=. downmessage.proto
```

## Development

## Test

To run the test suite, use:

```bash
LOCAL_IRODS=0 pytest -v tests/biomaj_tests.py
```

This command skips the test that need a local iRODS server.

Some test might fail due to network connection. You can skip them with:

```bash
NETWORK=0 pytest -v tests/biomaj_tests.py
```

## Run

### Message consumer

```bash
export BIOMAJ_CONFIG=path_to_config.yml
python bin/biomaj_download_consumer.py
```

### Web server

If package is installed via pip, you need a file named *gunicorn_conf.py* containing somehwhere on local server:

```python
def worker_exit(server, worker):
    from prometheus_client import multiprocess
    multiprocess.mark_process_dead(worker.pid)
```

If you cloned the repository and installed it via python setup.py install, just refer to the *gunicorn_conf.py* in the cloned repository.

```bash
export BIOMAJ_CONFIG=path_to_config.yml
rm -rf ..path_to/prometheus-multiproc
mkdir -p ..path_to/prometheus-multiproc
export prometheus_multiproc_dir=..path_to/prometheus-multiproc
gunicorn -c gunicorn_conf.py biomaj_download.biomaj_download_web:app
```

Web processes should be behind a proxy/load balancer, API base url /api/download

Prometheus endpoint metrics are exposed via /metrics on web server

## Retrying

A common problem when downloading a large number of files is the handling of temporary failures (network issues, server too busy to answer, etc.).
Since version 3.1.2, `biomaj-download` uses the [Tenacity library](https://github.com/jd/tenacity) which is designed to handle this.
This mechanism is configurable through 2 downloader-specific options (see [Download options](#download-options)): **stop_condition** and **wait_policy**.

When working on python code, you can pass instances of Tenacity's `stop_base` and `wait_base` respectively.
This includes classes defined in Tenacity or your own derived classes.

For bank configuration those options also parse strings read from the configuration file.
This parsing is based on the [Simple Eval library](https://github.com/danthedeckie/simpleeval).
The rules are straightforward:

* All concrete stop and wait classes defined in Tenacity (i.e. classes inheriting from `stop_base` and `wait_base` respectively) can be used
  by calling their constructor with the expected parameters.
  For example, the string `"stop_after_attempt(5)"` will create the desired object.
Note that stop and wait classes that need no argument must be used as constants (i.e. use `"stop_never"` and not `"stop_never()"`).
Currently, this is the case for `"stop_never"` (as in Tenacity) and `"wait_none"` (this slightly differs from Tenacity where it is `"wait_none()"`).
* You can use classes that allow to combine other stop conditions (namely `stop_all` and `stop_any`) or wait policies (namely `wait_combine`).
* Operator `+` can be used to add wait policies (similar to `wait_combine`).
* Operators `&` and `|` can be used to compose stop conditions (similar to `wait_all` and `wait_none` respectively).

However, in this case, you can't use your own conditions.
The complete list of stop conditions is:

* `stop_never` (although its use is discouraged)
* `stop_after_attempt`
* `stop_after_delay`
* `stop_when_event_set`
* `stop_all`
* `stop_any`

The complete list of wait policies is:

* `wait_none`
* `wait_fixed`
* `wait_random`
* `wait_incrementing`
* `wait_exponential`
* `wait_random_exponential`
* `wait_combine`
* `wait_chain`

Please refer to [Tenacity doc](https://tenacity.readthedocs.io/en/latest/) for their meaning and their parameters.

Examples (inspired by Tenacity doc):

* `"wait_fixed(3) + wait_random(0, 2)"` and `"wait_combine(wait_fixed(3), wait_random(0, 2))"` are equivalent and will wait 3 seconds + up to 2 seconds of random delay
* `"wait_chain(*([wait_fixed(3) for i in range(3)] + [wait_fixed(7) for i in range(2)] + [wait_fixed(9)]))"` will wait 3s for 3 attempts, 7s for the next 2 attempts and 9s for all attempts thereafter (here `+` is the list concatenation).
* `"wait_none + wait_random(1,2)"` will wait between 1s and 2s (since `wait_none` doesn't wait).
* `"stop_never | stop_after_attempt(5)"` will stop after 5 attempts (since `stop_never` never stops).

Note that some protocols (e.g. FTP) classify errors as temporary or permanent (for example trying to download inexisting file).
More generally, we could distinguish permanent errors based on error codes, etc. and not retry in this case.
However in our experience, so called permanent errors may well be temporary.
Therefore downloaders always retry whatever the error.
In some cases, this is a waste of time but generally this is worth it.

## Host keys

When using the `sftp` protocol, `biomaj-download` must check the host key.
Those keys are stored in a file (for instance `~/.ssh/known_hosts`).

Two options are available to configure this:

* **ssh_hosts_file** which sets the file to use
* **ssh_new_host** which sets what to do for a new host

When the host and the key are found in the file, the connection is accepted.
If the host is found but the key missmatches, the connection is rejected
(this usually indicates a problem or a change of configuration on the remote server).
When the host is not found, the decision depends on the value of **ssh_new_host**:

* `reject` means that the connection is rejected
* `accept` means that the connection is accepted
* `add` means that the connection is accepted and the key is added to the file

See the description of the options in [Download options](#download-options).

## Download options

Since version 3.0.26, you can use the `set_options` method to pass a dictionary of downloader-specific options.
The following list shows some options and their effect (the option to set is the key and the parameter is the associated value):

* **stop_condition**:
  * parameter: an instance of Tenacity `stop_base` or a string (see [Retrying](#retrying)).
  * downloader(s): all (except `LocalDownload`).
  * effect: sets the condition on which we should stop retrying to download a file.
  * default: `stop_after_attempt(3)` (i.e. stop after 3 attempts).
  * note: introduced in version 3.2.1.
* **wait_policy**:
  * parameter: an instance of Tenacity `wait_base` or a string (see [Retrying](#retrying)).
  * downloader(s): all (except `LocalDownload`).
  * effect: sets the wait policy between download attempts.
  * default: `wait_fixed(3)` (i.e. wait 3 seconds between attempts).
  * note: introduced in version 3.2.1.
* **skip_check_uncompress**:
  * parameter: bool.
  * downloader(s): all (except `LocalDownload`).
  * effect: if true, don't test the archives after download.
  * default: false (i.e. test the archives).
* **ssl_verifyhost**:
  * parameter: bool.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`).
  * effect: if false, don't check that the name of the remote server is the same than in the SSL certificate.
  * default: true (i.e. check host name).
  * note: it's generally a bad idea to disable this verification. However some servers are badly configured. See [here](https://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYHOST.html) for the corresponding cURL option.
* **ssl_verifypeer**:
  * parameter: bool.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`).
  * effect: if false, don't check the authenticity of the peer's certificate.
  * default: true (i.e. check authenticity).
  * note: it's generally a bad idea to disable this verification. However some servers are badly configured. See [here](https://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYPEER.html) for the corresponding cURL option.
* **ssl_server_cert**:
  * parameter: path of the certificate file.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`).
  * effect: use the certificate(s) in this file to verify the peer with.
  * default: use OS certificates.
  * note: see [here](https://curl.haxx.se/libcurl/c/CURLOPT_CAINFO.html) for the corresponding cURL option.
  * parameter: int.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`).
  * effect: sets the interval, in seconds, that the operating system will wait between sending keepalive probes.
  * default: cURL default (60s at the time of this writing).
  * note: see [here](https://curl.haxx.se/libcurl/c/CURLOPT_TCP_KEEPINTVL.html) for the corresponding cURL option.
* **ftp_method**:
  * parameter: one of `default`, `multicwd`, `nocwd`, `singlecwd` (case insensitive).
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`) - only used for `FTP(S)`.
  * effect: sets the method used to reach a file on a FTP(S) server (`nocwd` and `singlecwd` are usually faster but not always supported).
  * default: `default` (which is `multicwd` at the time of this writing as in cURL).
  * note: see [here](https://curl.haxx.se/libcurl/c/CURLOPT_FTP_FILEMETHOD.html) for the corresponding cURL option; introduced in version 3.1.2.
* **ssh_hosts_file**:
  * parameter: path of the known hosts file.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`) - only used for `SFTP`.
  * effect: sets the file used to read/store host keys for `SFTP`.
  * default: `~/.ssh/known_hosts` (where `~` is the home directory of the current user).
  * note: see [here](https://curl.haxx.se/libcurl/c/CURLOPT_SSH_KNOWNHOSTS.html) for the corresponding cURL option and the option below; introduced in version 3.2.1.
* **ssh_new_host**:
  * parameter: one of `reject`, `accept`, `add`.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`) - only used for `SFTP`.
  * effect: sets the policy to use for an unknown host.
  * default: `reject` (i.e. refuse new hosts - you must add them in the file for instance with `ssh` or `sftp`).
  * note: see [here](https://curl.haxx.se/libcurl/c/CURLOPT_SSH_KEYFUNCTION.html) for the corresponding cURL option and the option above; introduced in version 3.2.1.
* *allow_redirections*:
  * parameter: bool.
  * downloader(s): `CurlDownload` (and derived classes: `DirectFTPDownload`, `DirectHTTPDownload`) - only used for `HTTPS(S)`.
  * effect: sets the policy for `HTTP` redirections.
  * default: `true` (i.e. follow redirections).
  * note: see [here](https://curl.haxx.se/libcurl/c/CURLOPT_FOLLOWLOCATION.html) for the corresponding cURL option; introduced in version 3.2.3.

Those options can be set in bank properties.
See file `global.properties.example` in [biomaj module](https://github.com/genouest/biomaj).


3.2.12:
  Sort downloads in proper alphabetical order

3.2.11:
  fix direct handler in case of plugin usage

3.2.10:
  Regenerate proto messages

3.2.9:
  Replace nose by pytest for unit testing

3.2.8:
  Accept 257 error code for ftp

3.2.7
  Normalize pyyaml setup with other biomaj components

3.2.6:
  Disabled test with tenacity, compat.make_retry_state removed from lib

3.2.5:
  Fix regex handling for **/*

3.2.4:
  #39 directhttp download issues
    biomaj sends file name instead of file dict, workaround this
  #28 CurlDownload crashses if cURL doesn't support SFTP
  Minor python doc and error message updates
  Suppress yaml warnings

3.2.3:
  #30: raise errors when something in list() fail
  DirectHTTP(s)/DirectFTP(s): do not raise error on list step as HEAD may not be supported
  #35: allow redirections (closes #33)

3.2.2:
  #31 fix URL with multiple slashes
  Update demo password for ftps web site tests
  Remove python2 support

3.2.1:
  #26 Accept new keys for SFTP servers  (Closes #25)
  Strip extra slash characters in remote file list (due to regexp parsing)
  #20 Add a configurable mechanism to retry download when it fails
  #24 Speed up IRODDownload
  Introduce a method to perform configuration before network methods. Adapt implementation of generic methods and subclasses.
  Resolve bug when the parser analyse also the Message Of The Day when it wants only list of file. (#23)

3.1.2:
  #18 Add a protocol option to set CURLOPT_FTP_FILEMETHOD
  #19 Rename protocol options to options
  Fix copy of production files instead of download when files are in subdirectories

3.1.1:
  #17 Support MDTM command in directftp

3.1.0:
  #16 Don't change name after download in DirectHTTPDownloader
  PR #7 Refactor downloaders (*WARNING* breaks API)

3.0.27:
  Fix previous release broken with a bug in direct protocols

3.0.26:
  Change default download timeout to 1h
  #12 Allow FTPS protocol
  #14 Add mechanism for protocol specific options

3.0.25:
  Allow to use hardlinks in LocalDownload

3.0.24:
  Remove debug logs

3.0.23:
  Support spaces in remote file names

3.0.22:
  Fix **/* remote.files parsing

3.0.21:
  Fix traefik labels

3.0.20:
  Update pika dependency release
  Add tags for traefik support

3.0.19:
  Check archives after download
  Fix python regexps syntax (deprecation)

3.0.18:
  Rename protobuf and use specific package to avoid conflicts

3.0.17:
  Regenerate protobuf message desc, failing on python3

3.0.16:
  Add missing req in setup.py

3.0.15:
  Fix progress download control where could have infinite loop
  Add irods download

3.0.14:
  Allow setup of local_endpoint per service, else use default local_endpoint

3.0.13:
  In rate limiting, add progress vs total of download
  Fix rate limiting submission

3.0.12:
  Add retry in case of session creation failure
  disable web thread logging

3.0.11:
  Display progress of download by percent of downloads
  In case of contact error in downloadclient, retry connection

3.0.10:
  Feature #3: Add rate limiting option to limit number of parallel downloads for a client

3.0.9:
  Add host in prometheus stats
  Fix #2: allow setting http.group.file.size or http.group.file.date to -1 if not avalaible in http(s) page for regexp

3.0.8:
  Fix prometheus stats
  Add consul supervision

3.0.7:
  Change size type to int64

3.0.6:
  Fix download_or_copy to avoid downloading a file  existing in a previous production directory

3.0.4:
  Fixes on messages

3.0.3:
  Fix management of timeout leading to a crash when using biomaj.download parameter.

3.0.2:
  set rabbitmq parameter optional

3.0.1:
  add missing README etc.. in package

3.0.0:
  move download management out of biomaj main package