Apache Airflow - A platform to programmatically author, schedule, and monitor workflows
Apache Airflow (or simply Airflow) is a platform to programmatically author, schedule, and monitor workflows.
When workflows are defined as code, they become more maintainable, versionable, testable, and collaborative.
Use Airflow to author workflows as directed acyclic graphs (DAGs) of tasks. The Airflow scheduler executes your tasks on an array of workers while following the specified dependencies. Rich command line utilities make performing complex surgeries on DAGs a snap. The rich user interface makes it easy to visualize pipelines running in production, monitor progress, and troubleshoot issues when needed.
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Airflow works best with workflows that are mostly static and slowly changing. When DAG structure is similar from one run to the next, it allows for clarity around unit of work and continuity. Other similar projects include Luigi, Oozie and Azkaban.
Airflow is commonly used to process data, but has the opinion that tasks should ideally be idempotent (i.e. results of the task will be the same, and will not create duplicated data in a destination system), and should not pass large quantities of data from one task to the next (though tasks can pass metadata using Airflow's Xcom feature). For high-volume, data-intensive tasks, a best practice is to delegate to external services that specialize on that type of work.
Airflow is not a streaming solution, but it is often used to process real-time data, pulling data off streams in batches.
Apache Airflow is tested with:
| | Master version (dev) | Stable version (2.0.2) | Previous version (1.10.15) | | ------------ | ------------------------- | ------------------------ | ------------------------- | | Python | 3.6, 3.7, 3.8 | 3.6, 3.7, 3.8 | 2.7, 3.5, 3.6, 3.7, 3.8 | | Kubernetes | 1.20, 1.19, 1.18 | 1.20, 1.19, 1.18 | 1.18, 1.17, 1.16 | | PostgreSQL | 9.6, 10, 11, 12, 13 | 9.6, 10, 11, 12, 13 | 9.6, 10, 11, 12, 13 | | MySQL | 5.7, 8 | 5.7, 8 | 5.6, 5.7 | | SQLite | 3.15.0+ | 3.15.0+ | 3.15.0+ |
Note: MySQL 5.x versions are unable to or have limitations with running multiple schedulers -- please see the Scheduler docs. MariaDB is not tested/recommended.
Note: SQLite is used in Airflow tests. Do not use it in production. We recommend using the latest stable version of SQLite for local development.
As of Airflow 2.0 we agreed to certain rules we follow for Python and Kubernetes support. They are based on the official release schedule of Python and Kubernetes, nicely summarized in the Python Developer's Guide and Kubernetes version skew policy.
We drop support for Python and Kubernetes versions when they reach EOL. We drop support for those EOL versions in master right after EOL date, and it is effectively removed when we release the first new MINOR (Or MAJOR if there is no new MINOR version) of Airflow For example for Python 3.6 it means that we drop support in master right after 23.12.2021, and the first MAJOR or MINOR version of Airflow released after will not have it.
The "oldest" supported version of Python/Kubernetes is the default one. "Default" is only meaningful in terms of "smoke tests" in CI PRs which are run using this default version and default reference image available in DockerHub. Currently
apache/airflow:2.0.2images are both Python 3.6 images, however the first MINOR/MAJOR release of Airflow release after 23.12.2021 will become Python 3.7 images.
We support a new version of Python/Kubernetes in master after they are officially released, as soon as we make them work in our CI pipeline (which might not be immediate due to dependencies catching up with new versions of Python mostly) we release a new images/support in Airflow based on the working CI setup.
Note: If you're looking for documentation for master branch (latest development branch): you can find it on s.apache.org/airflow-docs.
For more information on Airflow Improvement Proposals (AIPs), visit the Airflow Wiki.
Official Docker (container) images for Apache Airflow are described in IMAGES.rst.
We publish Apache Airflow as
apache-airflowpackage in PyPI. Installing it however might be sometimes tricky because Airflow is a bit of both a library and application. Libraries usually keep their dependencies open and applications usually pin them, but we should do neither and both at the same time. We decided to keep our dependencies as open as possible (in
setup.py) so users can install different versions of libraries if needed. This means that from time to time plain
pip install apache-airflowwill not work or will produce unusable Airflow installation.
In order to have repeatable installation, however, introduced in Airflow 1.10.10 and updated in Airflow 1.10.12 we also keep a set of "known-to-be-working" constraint files in the orphan
constraints-1-10branches. We keep those "known-to-be-working" constraints files separately per major/minor Python version. You can use them as constraint files when installing Airflow from PyPI. Note that you have to specify correct Airflow tag/version/branch and Python versions in the URL.
pipinstallation is currently officially supported.
pip- especially when it comes to constraint vs. requirements management. Installing via
pip-toolsis not currently supported.
If you wish to install airflow using those tools you should use the constraint files and convert them to appropriate format and workflow that your tool requires.
pip install apache-airflow==2.0.2 \ --constraint "https://raw.githubusercontent.com/apache/airflow/constraints-2.0.2/constraints-3.7.txt"
pip install apache-airflow[postgres,google]==2.0.2 \ --constraint "https://raw.githubusercontent.com/apache/airflow/constraints-2.0.2/constraints-3.7.txt"
For information on installing provider packages check providers.
Apache Airflow is an Apache Software Foundation (ASF) project, and our official source code releases:
Following the ASF rules, the source packages released must be sufficient for a user to build and test the release provided they have access to the appropriate platform and tools.
There are other ways of installing and using Airflow. Those are "convenience" methods - they are not "official releases" as stated by the
ASF Release Policy, but they can be used by the users who do not want to build the software themselves.
Those are - in the order of most common ways people install Airflow:
dockertool, use them in Kubernetes, Helm Charts,
docker swarmetc. You can read more about using, customising, and extending the images in the Latest docs, and learn details on the internals in the IMAGES.rst document.
All those artifacts are not official releases, but they are prepared using officially released sources. Some of those artifacts are "development" or "pre-release" ones, and they are clearly marked as such following the ASF Policy.
Want to help build Apache Airflow? Check out our contributing documentation.
More than 400 organizations are using Apache Airflow in the wild.
Airflow is the work of the community, but the core committers/maintainers are responsible for reviewing and merging PRs as well as steering conversation around new feature requests. If you would like to become a maintainer, please review the Apache Airflow committer requirements.
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