Update Cloud Composer environments

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This page explains how an environment can be updated.

About update operations

When you change parameters of your environment, such as specifying new scaling and performance parameters, or installing custom PyPI packages, your environment updates.

After this operation is completed, changes become available in your environment.

For a single Cloud Composer environment, you can start only one update operation at a time. You must wait for an update operation to complete before starting another environment operation.

How updates affect running Airflow tasks

Caution: Some update operations terminate all running tasks.

When you run an update operation, Airflow schedulers and workers in your environment might require a restart. In this case, all currently running tasks are terminated. After the update operation is completed, Airflow schedules these tasks for a retry, depending on the way you configure retries for your DAGs.

Note: Airflow workers can get restarted as part of the environment maintenance, during the maintenance windows.

The following changes cause Airflow task termination:

• Upgrading your environment to a new version.
• Adding, changing, or deleting custom PyPI packages.
• Changing Cloud Composer environment variables.
• Adding or removing Airflow configuration options overrides, or changing their values.
• Changing Airflow workers' CPU, memory, or storage.

• Reducing the maximum number of Airflow workers, if the new value is lower than the number of currently running workers. For example, if an environment currently runs three workers, and the maximum is reduced to two.

The following changes don't cause Airflow task termination:

• Creating, updating, or deleting a DAG (not an update operation).
• Pausing or unpausing DAGs (not an update operation).
• Changing Airflow variables (not an update operation).
• Changing Airflow connections (not an update operation).
• Enabling or disabling Dataplex Universal Catalog Data Lineage integration.
• Changing environment's size.
• Changing the number of schedulers.
• Changing Airflow schedulers' CPU, memory, or storage.
• Changing the number of triggerers.
• Changing Airflow triggerers' CPU, memory, or storage.
• Changing Airflow web server's CPU, memory, or storage.
• Increasing or decreasing the minimum number of workers.
• Reducing the maximum number of Airflow workers. For example, if an environment currently runs two workers, and the maximum is reduced to three.
• Changing maintenance windows.
• Changing scheduled snapshots settings.
• Changing environment labels.

Updating with Terraform

Warning: If you attempt to change a configuration parameter that cannot be updated, Terraform deletes your environment and creates a new one with the new parameter value.

Run terraform plan before terraform apply to see if Terraform creates a new environment instead of updating it.

Before you begin

• Check that your account, the service account of your environment, and the Cloud Composer Service Agent account in your project have required permissions:

  • Your account must have a role that can trigger environment update operations.

  • The service account of your environment must have a role that has enough permissions to perform update operations.

• The gcloud composer environments update command terminates when the operation is finished. You can use the --async flag to avoid waiting for the operation to complete.

Update environments

For more information about updating your environment, see other documentation pages about specific update operations. For example:

• Override Airflow configuration options
• Set environment variables
• Install Python dependencies

• Scale environments

View environment details

Console

1. In Google Cloud console, go to the Environments page.

   Go to Environments

2. In the list of environments, click the name of your environment. The Environment details page opens.

gcloud

Run the following gcloud command:

gcloud composer environments describe ENVIRONMENT_NAME \
  --location LOCATION

Replace:

• ENVIRONMENT_NAME with the name of the environment.
• LOCATION with the region where the environment is located.

API

Construct an environments.get API request.

Example:

GET https://composer.googleapis.com/v1/projects/example-project/
locations/us-central1/environments/example-environment

Terraform

Run the terraform state show command for your environment's resource.

The name of your environment's Terraform resource might be different than the name of your environment.

terraform state show google_composer_environment.RESOURCE_NAME

Replace:

• RESOURCE_NAME with the name of your environment's resource.

Rolling back update changes

In some rare situations, an update operation might be interrupted (for example, because of a timeout) and the requested changes might not be rolled back in all environment components (such as the Airflow web server).

For example, an update operation might be installing or removing additional PyPI modules, re-defining or defining a new Airflow or Cloud Composer environment variable, or changing some Airflow-related parameters.

Such a situation might occur if an update operation is triggered when other operations are in progress, for example Cloud Composer cluster's autoscaling or a maintenance operation.

In such a situation, it's recommended to repeat the operation.

Duration of update or upgrade operations

The duration of update and upgrade operations is affected by the following factors:

• Most update or upgrade operations require restarting Airflow components like Airflow schedulers, workers and web servers. After a component is restarted, it must be initialized. During the initialization, Airflow schedulers and workers download the contents of /dags and /plugins folders from the environment's bucket. The process of syncing files to Airflow schedulers and workers isn't instantaneous and depends on the total size and number of all objects in these folders.

  We recommend to keep only DAG and plugin files in /dags and /plugins folders (respectively) and remove all other files. Too much data in /dags and /plugins folders might slow down the initialization of Airflow components and in certain cases might make the initialization not possible.

  We recommend to keep less than 30 MB of data in /dags and /plugins folders, and to definitely not exceed 100 MB size of data. For more information, also see Handling large number of DAGs and plugins

• The size of the Airflow database might significantly increase the time of upgrade operations. We recommend to maintain the Airflow database size by configuring a database retention policy.

What's next

• Upgrade environments
• Override Airflow configuration options