Issue/#860 Update README (#869)

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DEVELOPMENT.md

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+# Development
+This document outlines how to set up the project for development in extensive
+detail.
+
+*Only developing on Linux is officially supported, but people have gotten the
+project to build on Windows using the WSL.*
+
+## System dependencies
+You will need the following software installed on your system:
+-   [Docker](https://docs.docker.com/engine/)
+-   [Docker Compose](https://github.com/docker/compose)
+-   [Python 3.9](https://www.python.org/downloads/)
+-   [Pipenv](https://github.com/pypa/pipenv/)
+
+Once you have Docker installed, make sure to add yourself to the `docker` group
+so that you can run docker commands without `sudo`. You will need to relogin
+for the changes to take effect.
+```
+$ sudo usermod -aG docker <user>
+```
+
+It's very likely that the right version of Python may not be available in your
+distro's package repositories. In this case you will need to install from
+source. Make sure that you compile with the
+`--enable-loadable-sqlite-extensions` flag otherwise some of the dependencies
+will not work.
+
+```
+$ ./configure --enable-loadable-sqlite-extensions
+```
+
+There are a number of steps to compiling Python from source so make sure to
+look up a guide if you haven't done it before.
+
+Once you have Pipenv installed, you might want to enable the 'movable' virtual
+environment option that will put your virtual environment into the traditional
+`.venv` directory of the project. Just add the following line to your `.bashrc`
+and reload your terminal:
+```
+export PIPENV_VENV_IN_PROJECT=1
+```
+
+## Application Dependencies
+The lobby server needs the FAF MySQL database for storing persistent state.
+Follow the instructions on the [faf-db repo](https://github.com/FAForever/db)
+to setup an instance of the database.
+
+If the database version defined in
+[`.github/workflows/test.yml`](.github/workflows/test.yml) does not match
+the one defined in your `docker-compose.yml`, you will need to update the
+compose file and then re-run the migrations.
+
+Find the section in `docker-compose.yml` that looks like this and change the
+version number to the required version in
+[`.github/workflows/test.yml`](.github/workflows/test.yml).
+```
+faf-db-migrations:
+  container_name: faf-db-migrations
+  image: faforever/faf-db-migrations:<version tag>
+```
+
+Then run the migrations with the following command.
+```
+$ docker-compose run faf-db-migrations migrate
+```
+
+Install the pinned versions of the dependencies (and dev dependencies) to a
+virtual environment using pipenv by running:
+```
+$ pipenv sync --dev
+```
+
+## Running the development server
+Once you have installed all the application dependencies including the FAF
+database, you can start the server in development mode with:
+```
+$ pipenv run devserver
+```
+
+You will probably see a number of errors and warnings show up in the log which
+is completely normal for a development setup. If you see any of the following,
+they can be safely ignored:
+
+```
+WARNING  Twilio is not set up. You must set TWILIO_ACCOUNT_SID and TWILIO_TOKEN to use the Twilio ICE servers.
+WARNING  GEO_IP_LICENSE_KEY not set! Unable to download GeoIP database!
+WARNING  Unable to connect to RabbitMQ. Is it running?
+ConnectionError: [Errno 111] Connect call failed ('127.0.0.1', 5672)
+WARNING  Not connected to RabbitMQ, unable to declare exchange.
+ERROR    Failure updating NickServ password for test
+```
+
+**Note:** *The pipenv scripts are NOT meant for production deployment. For
+deployment use [faf-stack](https://github.com/FAForever/faf-stack).*
+
+## Running the tests
+
+The unit tests are written using [pytest](https://docs.pytest.org/en/latest) and
+can be run through the pipenv shortcut:
+```
+$ pipenv run tests
+```
+Any arguments passed to the shortcut will be forwarded to pytest, so the usual
+pytest options can be used for test selection. For instance, to run all unit
+tests containing the keyword "ladder":
+```
+$ pipenv run tests tests/unit_tests -k ladder
+```
+
+If you are running `pytest` by some other means (e.g. with PyCharm) you may need
+to provide the database configuration as command line arguments:
+```
+--mysql_host=MYSQL_HOST
+                      mysql host to use for test database
+--mysql_username=MYSQL_USERNAME
+                      mysql username to use for test database
+--mysql_password=MYSQL_PASSWORD
+                      mysql password to use for test database
+--mysql_database=MYSQL_DATABASE
+                      mysql database to use for tests
+--mysql_port=MYSQL_PORT
+                      mysql port to use for tests
+```
+
+For further information on available command line arguments run `pytest --help`
+or see the official
+[pytest documentation](https://docs.pytest.org/en/latest/usage.html).
+
+There are also some integration tests which simulate real traffic to the test
+server.
+```
+$ pipenv run integration
+```
+
+Some of them may fail depending on the configuration deployed on the test
+server.
+
+## Other tools
+
+There are some pre-commit hooks that can fix basic formatting issues for you
+to make the review process go smoother. You can install them by running:
+```
+$ python3 -m pip install pre-commit
+$ pre-commit install
+```
+
+(optional) Run against all the files (usually `pre-commit` will only run on the
+changed files during git hooks):
+```
+$ pre-commit run --all-files
+```
+
+You can check for possible unused code with `vulture` by running:
+```
+$ pipenv run vulture
+```
+
+It tends to produce a lot of false positives, but it can provide a good place
+to start.
+
+## Building with Docker
+
+The recommended way to deploy the server is with
+[faf-stack](https://github.com/FAForever/faf-stack). However, you can also
+build the docker image manually.
+
+Follow the steps to get [faf-db](https://github.com/FAForever/db) setup, the
+following assumes the db container is called `faf-db` and the database is called
+`faf` and the root password is `banana`.
+
+Then use Docker to build and run the server as follows
+```
+$ docker build -t faf-server .
+$ docker run --link faf-db:db -p 8001:8001 -d faf-server
+```
+
+Check if the container is running with
+```
+$ docker ps
+```
+
+If you cannot find `faf-server` in the list, run `docker run` without `-d` to
+see what happens.
+
+### Configuration
+
+If you have for example a different root password or database name than the default
+`DB_PASSWORD` and `DB_NAME` entries in
+[config.py](https://github.com/FAForever/server/blob/develop/server/config.py),
+you should provide a custom configuration file.
+This file will be used for all variables that it defines
+while the default values of `config.py` still apply for those it doesn't.
+To use your custom configuration file, pass its location as an environment
+variable to docker:
+```
+$ docker run --link faf-db:db -p 8001:8001 -e CONFIGURATION_FILE=<path> faf-server
+```
+
+You can find an example configuration file under
+[tests/data/test_conf.yaml](https://github.com/FAForever/server/blob/develop/tests/data/test_conf.yaml).
+
+## Administrator/root privileges
+
+On Linux, root privileges are generally not needed. If you find that a command
+will not work unless run as root, it probably means that you have a file
+permission issue that you should fix. For instance if you ran the server as a
+docker container, it may have created certain files (like the GeoIP database) as
+root, and you should `chown` them or delete them before running the unit tests
+or the devserver.
+
+On Windows you may also find that some issues go away when running as
+administrator. This may be because you have set up your tools to install for the
+whole system instead of just the current user. For example if you have issues
+with pipenv you can try installing it with the `--user` option:
+```
+$ pip install --user pipenv
+```