CONTRIBUTORS_QUICK_START.rst

Contributor's Quick Start

• Note to Starters
• Local machine development
  • Docker Community Edition
  • Docker Compose
  • Pyenv and setting up virtual-env
  • Forking and cloning Project
• Typical development tasks
  • Setting up Breeze
  • Using Breeze
  • Configuring Pre-commit
  • Installing airflow in the local venv
  • Running tests with Breeze
• Contribution guide
  • Raising Pull Request
  • Syncing Fork and rebasing Pull request
• Using your IDE
• Using Remote development environments

Note to Starters

Airflow is quite a complex project, and setting up a working environment, but we made it rather simple if you follow the guide.

There are three ways you can run the Airflow dev env:

1. With a Docker Containers and Docker Compose (on your local machine). This environment is managed with Breeze tool written in Python that makes the environment management, yeah you guessed it - a breeze.
2. With a local virtual environment (on your local machine).
3. With a remote, managed environment (via remote development environment)

Before deciding which method to choose, there are a couple factors to consider:

• Running Airflow in a container is the most reliable way: it provides a more consistent environment and allows integration tests with a number of integrations (cassandra, mongo, mysql, etc.). However it also requires 4GB RAM, 40GB disk space and at least 2 cores.
• If you are working on a basic feature, installing Airflow on a local environment might be sufficient. For a comprehensive venv tutorial - visit Virtual Env guide
• You need to have usually a paid account to access managed, remote virtual environment.

Local machine development

If you do not work with remote development environment, you need those prerequisites.

1. Docker Community Edition
2. Docker Compose
3. pyenv (you can also use pyenv-virtualenv or virtualenvwrapper)

The below setup describe Ubuntu installation. It might be slightly different on different machines.

Docker Community Edition

1. Installing required packages for Docker and setting up docker repo

$ sudo apt-get update

$ sudo apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg-agent \
    software-properties-common

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

$ sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

2. Install Docker

$ sudo apt-get update
$ sudo apt-get install docker-ce docker-ce-cli containerd.io

3. Creating group for docker and adding current user to it.

$ sudo groupadd docker
$ sudo usermod -aG docker $USER

Note : After adding user to docker group Logout and Login again for group membership re-evaluation.

4. Test Docker installation

$ docker run hello-world

Docker Compose

1. Installing latest version of Docker Compose

$ COMPOSE_VERSION="$(curl -s https://api.github.com/repos/docker/compose/releases/latest | grep '"tag_name":'\
| cut -d '"' -f 4)"

$ COMPOSE_URL="https://github.com/docker/compose/releases/download/${COMPOSE_VERSION}/\
docker-compose-$(uname -s)-$(uname -m)"

$ sudo curl -L "${COMPOSE_URL}" -o /usr/local/bin/docker-compose

$ sudo chmod +x /usr/local/bin/docker-compose

2. Verifying installation

$ docker-compose --version

Pyenv and setting up virtual-env

Note: You might have issues with pyenv if you have a Mac with an M1 chip. Consider using virtualenv as an alternative.

1. Install pyenv and configure your shell's environment for Pyenv as suggested in Pyenv README
2. After installing pyenv, you need to install a few more required packages for Airflow

$ sudo apt-get install openssl sqlite default-libmysqlclient-dev libmysqlclient-dev postgresql

3. Restart your shell so the path changes take effect and verifying installation

$ exec $SHELL
$ pyenv --version

4. Checking available version, installing required Python version to pyenv and verifying it

$ pyenv install --list
$ pyenv install 3.8.5
$ pyenv versions

5. Creating new virtual environment named airflow-env for installed version python. In next chapter virtual environment airflow-env will be used for installing airflow.

$ pyenv virtualenv 3.8.5 airflow-env

6. Entering virtual environment airflow-env

$ pyenv activate airflow-env

Forking and cloning Project

1. Goto https://github.com/apache/airflow/ and fork the project.

   

2. Goto your github account's fork of airflow click on Code you will find the link to your repo.

   

3. Follow Cloning a repository to clone the repo locally (you can also do it in your IDE - see the Using your IDE chapter below.

Typical development tasks

For many of the development tasks you will need Breeze to be configured. Breeze is a development environment which uses docker and docker-compose and it's main purpose is to provide a consistent and repeatable environment for all the contributors and CI. When using Breeze you avoid the "works for me" syndrome - because not only others can reproduce easily what you do, but also the CI of Airflow uses the same environment to run all tests - so you should be able to easily reproduce the same failures you see in CI in your local environment.

Setting up Breeze

1. Install pipx - follow the instructions in Install pipx
2. Run pipx install -e ./dev/breeze in your checked-out repository. Make sure to follow any instructions printed by pipx during the installation - this is needed to make sure that breeze command is available in your PATH.
3. Initialize breeze autocomplete

$ breeze setup autocomplete

4. Initialize breeze environment with required python version and backend. This may take a while for first time.

$ breeze --python 3.7 --backend postgres

Note

If you encounter an error like "docker.credentials.errors.InitializationError: docker-credential-secretservice not installed or not available in PATH", you may execute the following command to fix it:

$ sudo apt install golang-docker-credential-helper

Once the package is installed, execute the breeze command again to resume image building.

5. When you enter Breeze environment you should see prompt similar to root@e4756f6ac886:/opt/airflow#. This means that you are inside the Breeze container and ready to run most of the development tasks. You can leave the environment with exit and re-enter it with just breeze command. Once you enter breeze environment, create airflow tables and users from the breeze CLI. airflow db reset is required to execute at least once for Airflow Breeze to get the database/tables created. If you run tests, however - the test database will be initialized automatically for you.

root@b76fcb399bb6:/opt/airflow# airflow db reset
root@b76fcb399bb6:/opt/airflow# airflow users create --role Admin --username admin --password admin \
  --email [email protected] --firstname foo --lastname bar

6. Exiting Breeze environment. After successfully finishing above command will leave you in container, type exit to exit the container. The database created before will remain and servers will be running though, until you stop breeze environment completely.

root@b76fcb399bb6:/opt/airflow#
root@b76fcb399bb6:/opt/airflow# exit

6. You can stop the environment (which means deleting the databases and database servers running in the background) via breeze stop command.

$ breeze stop

Using Breeze

1. Starting breeze environment using breeze start-airflow starts Breeze environment with last configuration run( In this case python and backend will be picked up from last execution breeze --python 3.8 --backend postgres) It also automatically starts webserver, backend and scheduler. It drops you in tmux with scheduler in bottom left and webserver in bottom right. Use [Ctrl + B] and Arrow keys to navigate.

$ breeze start-airflow

    Use CI image.

 Branch name:            main
 Docker image:           ghcr.io/apache/airflow/main/ci/python3.8:latest
 Airflow source version: 2.4.0.dev0
 Python version:         3.8
 Backend:                mysql 5.7


 Port forwarding:

 Ports are forwarded to the running docker containers for webserver and database
   * 12322 -> forwarded to Airflow ssh server -> airflow:22
   * 28080 -> forwarded to Airflow webserver -> airflow:8080
   * 25555 -> forwarded to Flower dashboard -> airflow:5555
   * 25433 -> forwarded to Postgres database -> postgres:5432
   * 23306 -> forwarded to MySQL database  -> mysql:3306
   * 21433 -> forwarded to MSSQL database  -> mssql:1443
   * 26379 -> forwarded to Redis broker -> redis:6379

 Here are links to those services that you can use on host:
   * ssh connection for remote debugging: ssh -p 12322 [email protected] pw: airflow
   * Webserver: http://127.0.0.1:28080
   * Flower:    http://127.0.0.1:25555
   * Postgres:  jdbc:postgresql://127.0.0.1:25433/airflow?user=postgres&password=airflow
   * Mysql:     jdbc:mysql://127.0.0.1:23306/airflow?user=root
   * MSSQL:     jdbc:sqlserver://127.0.0.1:21433;databaseName=airflow;user=sa;password=Airflow123
   * Redis:     redis://127.0.0.1:26379/0

• Alternatively you can start the same using following commands

  1. Start Breeze

  $ breeze --python 3.8 --backend postgres

  2. Open tmux

  $ root@0c6e4ff0ab3d:/opt/airflow# tmux

  3. Press Ctrl + B and "

  $ root@0c6e4ff0ab3d:/opt/airflow# airflow scheduler

  4. Press Ctrl + B and %

  $ root@0c6e4ff0ab3d:/opt/airflow# airflow webserver

2. Now you can access airflow web interface on your local machine at http://127.0.0.1:28080 with user name admin and password admin.

   

3. Setup mysql database in MySQL Workbench with Host 127.0.0.1, port 23306, user root and password blank(leave empty), default schema airflow.

   

4. Stopping breeze

root@f3619b74c59a:/opt/airflow# stop_airflow
root@f3619b74c59a:/opt/airflow# exit
$ breeze stop

5. Knowing more about Breeze

$ breeze --help

For more information visit : Breeze documentation

Following are some of important topics of Breeze documentation:

• Choosing different Breeze environment configuration

• Troubleshooting Breeze environment

• Installing Additional tools to the Docker Image

• Breeze Command-Line Interface Reference

• Cleaning the environment

Configuring Pre-commit

Before committing changes to github or raising a pull request, code needs to be checked for certain quality standards such as spell check, code syntax, code formatting, compatibility with Apache License requirements etc. This set of tests are applied when you commit your code.

To avoid burden on CI infrastructure and to save time, Pre-commit hooks can be run locally before committing changes.

1. Installing required packages

$ sudo apt install libxml2-utils

2. Installing required Python packages

$ pyenv activate airflow-env
$ pip install pre-commit

3. Go to your project directory

$ cd ~/Projects/airflow

1. Running pre-commit hooks

$ pre-commit run --all-files
  No-tabs checker......................................................Passed
  Add license for all SQL files........................................Passed
  Add license for all other files......................................Passed
  Add license for all rst files........................................Passed
  Add license for all JS/CSS/PUML files................................Passed
  Add license for all JINJA template files.............................Passed
  Add license for all shell files......................................Passed
  Add license for all python files.....................................Passed
  Add license for all XML files........................................Passed
  Add license for all yaml files.......................................Passed
  Add license for all md files.........................................Passed
  Add license for all mermaid files....................................Passed
  Add TOC for md files.................................................Passed
  Add TOC for upgrade documentation....................................Passed
  Check hooks apply to the repository..................................Passed
  black................................................................Passed
  Check for merge conflicts............................................Passed
  Debug Statements (Python)............................................Passed
  Check builtin type constructor use...................................Passed
  Detect Private Key...................................................Passed
  Fix End of Files.....................................................Passed
  ...........................................................................

5. Running pre-commit for selected files

$ pre-commit run  --files airflow/decorators.py tests/utils/test_task_group.py

6. Running specific hook for selected files

$ pre-commit run black --files airflow/decorators.py tests/utils/test_task_group.py
  black...............................................................Passed
$ pre-commit run run-flake8 --files airflow/decorators.py tests/utils/test_task_group.py
  Run flake8..........................................................Passed

7. Enabling Pre-commit check before push. It will run pre-commit automatically before committing and stops the commit

$ cd ~/Projects/airflow
$ pre-commit install
$ git commit -m "Added xyz"

8. To disable Pre-commit

$ cd ~/Projects/airflow
$ pre-commit uninstall

• For more information on visit STATIC_CODE_CHECKS.rst

• Following are some of the important links of STATIC_CODE_CHECKS.rst

  • Pre-commit Hooks
  • Running Static Code Checks via Breeze

Installing airflow in the local venv

1. It may require some packages to be installed; watch the output of the command to see which ones are missing.

$ sudo apt-get install sqlite libsqlite3-dev default-libmysqlclient-dev postgresql
$ ./scripts/tools/initialize_virtualenv.py

2. Add following line to ~/.bashrc in order to call breeze command from anywhere.

export PATH=${PATH}:"/home/${USER}/Projects/airflow"
source ~/.bashrc

Running tests with Breeze

You can usually conveniently run tests in your IDE (see IDE below) using virtualenv but with Breeze you can be sure that all the tests are run in the same environment as tests in CI.

All Tests are inside ./tests directory.

• Running Unit tests inside Breeze environment.

  Just run pytest filepath+filename to run the tests.

root@63528318c8b1:/opt/airflow# pytest tests/utils/test_decorators.py
======================================= test session starts =======================================
platform linux -- Python 3.8.6, pytest-6.0.1, py-1.9.0, pluggy-0.13.1 -- /usr/local/bin/python
cachedir: .pytest_cache
rootdir: /opt/airflow, configfile: pytest.ini
plugins: celery-4.4.7, requests-mock-1.8.0, xdist-1.34.0, flaky-3.7.0, rerunfailures-9.0, instafail
-0.4.2, forked-1.3.0, timeouts-1.2.1, cov-2.10.0
setup timeout: 0.0s, execution timeout: 0.0s, teardown timeout: 0.0s
collected 3 items

tests/utils/test_decorators.py::TestApplyDefault::test_apply PASSED                         [ 33%]
tests/utils/test_decorators.py::TestApplyDefault::test_default_args PASSED                  [ 66%]
tests/utils/test_decorators.py::TestApplyDefault::test_incorrect_default_args PASSED        [100%]

======================================== 3 passed in 1.49s ========================================

• Running All the test with Breeze by specifying required python version, backend, backend version

$ breeze --backend postgres --postgres-version 10 --python 3.8 --db-reset --test-type All  tests

• Running specific type of test

  • Types of tests
  • Running specific type of test

  $ breeze --backend postgres --postgres-version 10 --python 3.8 --db-reset --test-type Core

• Running Integration test for specific test type

  • Running an Integration Test

  $ breeze --backend postgres --postgres-version 10 --python 3.8 --db-reset --test-type All --integration mongo

• For more information on Testing visit : TESTING.rst

• Following are the some of important topics of TESTING.rst

  • Airflow Test Infrastructure
  • Airflow Unit Tests
  • Helm Unit Tests
  • Airflow Integration Tests
  • Running Tests with Kubernetes
  • Airflow System Tests
  • Local and Remote Debugging in IDE

Contribution guide

• To know how to contribute to the project visit CONTRIBUTING.rst

• Following are some of important links of CONTRIBUTING.rst

  • Types of contributions
  • Roles of contributor
  • Workflow for a contribution

Raising Pull Request

1. Go to your GitHub account and open your fork project and click on Branches

   

2. Click on New pull request button on branch from which you want to raise a pull request.

   

3. Add title and description as per Contributing guidelines and click on Create pull request.

   

Syncing Fork and rebasing Pull request

Often it takes several days or weeks to discuss and iterate with the PR until it is ready to merge. In the meantime new commits are merged, and you might run into conflicts, therefore you should periodically synchronize main in your fork with the apache/airflow main and rebase your PR on top of it. Following describes how to do it.

• Update new changes made to apache:airflow project to your fork

• Rebasing pull request

Using your IDE

If you are familiar with Python development and use your favourite editors, Airflow can be setup similarly to other projects of yours. However, if you need specific instructions for your IDE you will find more detailed instructions here:

• Pycharm/IntelliJ
• Visual Studio Code

Using Remote development environments

In order to use remote development environment, you usually need a paid account, but you do not have to setup local machine for development.

• GitPod
• GitHub Codespaces