 .. Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at

 ..   http://www.apache.org/licenses/LICENSE-2.0

 .. Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.

.. image:: /img/helm-logo.svg
   :width: 100
   :class: no-scaled-link

Helm Chart for Apache Airflow
=============================

.. toctree::
   :hidden:

   Home <self>
   quick-start
   airflow-configuration
   adding-connections-and-variables
   manage-dag-files
   manage-logs
   setting-resources-for-containers
   keda
   using-additional-containers
   customizing-workers
   customizing-labels
   Installing from sources<installing-helm-chart-from-sources>
   Extending the Chart<extending-the-chart>

.. toctree::
   :hidden:
   :caption: Guides

   production-guide
   service-account-token-examples
   upgrading-to-airflow-3

.. toctree::
   :hidden:
   :caption: References

   Parameters <parameters-ref>
   release_notes


This chart bootstraps an `Airflow <https://airflow.apache.org>`__
deployment on a `Kubernetes <http://kubernetes.io>`__ cluster using the
`Helm <https://helm.sh>`__ package manager.

Requirements
------------

.. jinja:: global_ctx

   -  Kubernetes {{ min_k8s_version }}+ cluster
   -  Helm {{ helm_version }}+
   -  PV provisioner support in the underlying infrastructure (optionally)

Features
--------

* Supported executors: ``LocalExecutor``, ``CeleryExecutor``, ``KubernetesExecutor``
* Supported multiple Executors
* Supported AWS executors with AWS provider version ``9.18.0+``:

   * ``airflow.providers.amazon.aws.executors.batch.AwsBatchExecutor``
   * ``airflow.providers.amazon.aws.executors.ecs.AwsEcsExecutor``
   * ``airflow.providers.amazon.aws.executors.aws_lambda.lambda_executor.AwsLambdaExecutor``

* Supported Edge executor with edge3 provider version ``1.6.0+``:

   * ``airflow.providers.edge3.executors.EdgeExecutor``

* Supported Airflow version: ``3.1+``
* Supported database backend: ``PostgreSQL``, ``MySQL``
* Autoscaling for ``CeleryExecutor`` provided by KEDA
* ``PostgreSQL`` and ``PgBouncer`` with a battle-tested configuration
* Monitoring:

   * StatsD/Prometheus metrics for Airflow
   * Prometheus metrics for PgBouncer
   * Flower

* Automatic database migration after a new deployment
* Administrator account creation during deployment
* Kerberos secure configuration
* One-command deployment for any type of executor. You don't need to provide other services e.g. Redis/Database to test the Airflow

.. _helm_chart_install:

Installing the Helm Chart
-------------------------

To install this chart using Helm 3, run the following commands:

.. code-block:: bash

   helm repo add apache-airflow https://airflow.apache.org
   helm upgrade --install airflow apache-airflow/airflow --namespace airflow --create-namespace

The command deploys Airflow on the Kubernetes cluster with the default configuration in the airflow namespace.
The :doc:`parameters-ref` section lists the parameters that can be configured during installation.


.. tip::

   List all releases using ``helm list``.

Upgrading the deployed Helm Chart
---------------------------------

To upgrade the chart with the release name ``airflow``:

.. code-block:: bash

   helm upgrade airflow apache-airflow/airflow --namespace airflow

.. note::

   To upgrade to a new version of the chart, run ``helm repo update`` first.

.. tip::

   By setting ``--install`` flag on the ``helm upgrade`` command, Helm Chart will be installed if it wasn't deployed before.

Uninstalling the deployed Helm Chart
------------------------------------

To uninstall/delete the ``airflow`` deployment:

.. code-block:: bash

   helm delete airflow --namespace airflow

The command removes all the Kubernetes components associated with the chart and deletes the release.

.. note::

   Some Kubernetes resources created by the chart `helm hooks <https://helm.sh/docs/topics/charts_hooks/#hook-resources-are-not-managed-with-corresponding-releases>`__ might be left in the namespace after executing ``helm uninstall``.

Installing the Helm Chart with Argo CD, Flux, Rancher or Terraform
------------------------------------------------------------------

When installing the chart using Argo CD, Flux, Rancher or Terraform, you **must** set the four following values, or your application
will not start as the migrations will not be run:

.. code-block:: yaml
   :caption: values.yaml

   createUserJob:
     useHelmHooks: false
     applyCustomEnv: false
   migrateDatabaseJob:
     useHelmHooks: false
     applyCustomEnv: false

This is so these CI/CD services can perform updates without issues and preserve the immutability of Kubernetes Job manifests.

.. note::

   This applies to the chart installation with usage of ``--wait`` flag in ``helm install`` or ``helm upgrade`` command.

.. note::

   While deploying this Helm Chart with Argo, you might encounter issues with database migrations not running automatically on upgrade.

To run database migrations with Argo CD automatically, you will need to add:

.. code-block:: yaml
   :caption: values.yaml

   migrateDatabaseJob:
     jobAnnotations:
       "argocd.argoproj.io/hook": Sync

This will run database migrations every time there is a ``Sync`` event in Argo CD. While it is not ideal to run the migrations on every sync, it is a trade-off that allows them to be run automatically.

If you use the ``CeleryExecutor`` with the built-in Redis, it is recommended that you set up a static Redis password either by supplying ``redis.passwordSecretName`` and ``data.brokerUrlSecretName`` or ``redis.password``.

.. note::

   Due to security concerns, it is not advised to set sensitive values like passwords within the ``values.yaml``.

.. note::

   By default, Helm hooks are also enabled for ``extraSecrets`` or ``extraConfigMaps``. When using the above CI/CD tools, you might encounter issues due to these default hooks.

To avoid potential problems, it is recommended to disable these hooks by setting ``useHelmHooks=false`` as shown in the following examples:

.. code-block:: yaml
   :caption: values.yaml

   extraSecrets:
     '{{ .Release.Name }}-example':
       useHelmHooks: false
       data: |
         AIRFLOW_VAR_HELLO_MESSAGE: "Hi!"

   extraConfigMaps:
     '{{ .Release.Name }}-example':
       useHelmHooks: false
       data: |
         AIRFLOW_VAR_HELLO_MESSAGE: "Hi!"

Naming Conventions
------------------

For new installations it is highly recommended to start using standard naming conventions.
It is not enabled by default as this may cause unexpected behaviours on existing installations. However you can enable it using ``useStandardNaming``:

.. code-block:: yaml
   :caption: values.yaml

   useStandardNaming: true

For existing installations, all your resources will be recreated with a new name and helm will delete previous resources.

.. note::

   In current ``useStandardNaming`` implementation, the standard name is not affecting Kubernetes Service Accounts created by Airflow Helm Chart.

This won't delete existing PVCs for logs used by StatefulSets/Deployments, but it will recreate them with brand new PVCs.
If you do want to preserve logs history you'll need to manually copy the data of these volumes into the new volumes after
deployment. Depending on what storage backend/class you're using, this procedure may vary. If you don't mind starting
with fresh logs/redis volumes, you can delete the old persistent volume claims, for example:

.. code-block:: bash

   kubectl delete pvc -n airflow logs-gta-triggerer-0
   kubectl delete pvc -n airflow logs-gta-worker-0
   kubectl delete pvc -n airflow redis-db-gta-redis-0

.. note::

   If you do not change ``useStandardNaming`` or ``fullnameOverride`` after upgrade, you can proceed as usual and no unexpected behaviours will be presented.
