Set environment variables

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This page explains how to set environment variables in your Cloud Composer environment.

You can use environment variables as an alternative to Airflow variables when providing runtime configuration for your DAGs. Airflow variables are set in the Airflow database, while environment variables are set in the Airflow worker's container.

As an example, you can use an environment variable's name as is in a command that is run by a BashOperator, or get this value from the os.environ object in the DAG, or use an Airflow variable instead.

Environment variables are persistent. Once you specify an environment variable, Airflow keeps using it until you remove the variable from your environment.

Cloud Composer sets its own reserved environment variables for controlling environments.

Name format

Environment variables must match the regular expression [a-zA-Z_][a-zA-Z0-9_]*.

Airflow configuration options

It is not possible to specify variables that change Apache Airflow configuration options.

The variables cannot use the AIRFLOW__{SECTION}__{KEY} format or match the regular expression AIRFLOW__[A-Z0-9_]+__[A-Z0-9_]+. For example, it is not possible to set AIRFLOW__WEBSERVER__DAG_DEFAULT_VIEW.

Instead, you can override Airflow configuration options.

Reserved variables

The following variable names are reserved by Cloud Composer. It is not possible to create variables with these names.

  • AIRFLOW_DATABASE_VERSION
  • AIRFLOW_HOME
  • AIRFLOW_SRC_DIR
  • AIRFLOW_WEBSERVER
  • AUTO_GKE
  • CLOUDSDK_METRICS_ENVIRONMENT
  • CLOUD_LOGGING_ONLY
  • COMPOSER_AGENT_BUILD_SERVICE_ACCOUNT
  • COMPOSER_ENVIRONMENT
  • COMPOSER_GKE_LOCATION
  • COMPOSER_GKE_NAME
  • COMPOSER_GKE_ZONE
  • COMPOSER_LOCATION
  • COMPOSER_OPERATION_UUID
  • COMPOSER_PYTHON_VERSION
  • COMPOSER_VERSION
  • CONTAINER_NAME
  • C_FORCE_ROOT
  • DAGS_FOLDER
  • GCP_PROJECT
  • GCP_TENANT_PROJECT
  • GCSFUSE_EXTRACTED
  • GCS_BUCKET
  • GKE_CLUSTER_NAME
  • GKE_IN_TENANT
  • GOOGLE_APPLICATION_CREDENTIALS
  • MAJOR_VERSION
  • MINOR_VERSION
  • PATH
  • PIP_DISABLE_PIP_VERSION_CHECK
  • PORT
  • PROJECT_ID
  • PYTHONPYCACHEPREFIX
  • PYTHONWARNINGS
  • REDIS_PASSWORD
  • REDIS_PORT
  • REDIS_USER
  • SQL_DATABASE
  • SQL_HOST
  • SQL_INSTANCE
  • SQL_PASSWORD
  • SQL_PROJECT
  • SQL_REGION
  • SQL_USER

Set environment variables for new environments

You can specify environment variables when you create an environment. For more information, see Create environments.

Set environment variables for existing environments

Console

To set environment variables for an existing environment:

  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.

  3. Go to the Environment variables tab and click Edit.

  4. Add, change, or delete environment variables for your environment:

    • In the Name field, specify the variable name.
    • In the Value field, specify the variable value.
    • To add an extra variable, click Add environment variable.
    • To delete a variable, hold the pointer over a variable, then click Delete item.

gcloud

Following arguments control environment variables:

  • --update-env-variables specifies a comma-separated list of environment variables to create or update.

  • --remove-env-variables specifies a comma-separated list of environment variables to delete.

  • --clear-env-variables deletes all existing environment variables.

gcloud composer environments update \
  ENVIRONMENT_NAME \
  --location LOCATION \
  --update-env-variables=NAME=VALUE

Replace:

  • ENVIRONMENT_NAME with the name of the environment.
  • LOCATION with the region where the environment is located.
  • NAME with the name of the variable that you want to create or update.
  • VALUE with the value for the variable.
  • To add more than one variable, separate the definitions with commas: NAME=VALUE,NAME=VALUE,....

Example:

gcloud composer environments update \
  example-environment \
  --location us-central1 \
  --update-env-variables=EXAMPLE_VARIABLE=True,ANOTHER_VARIABLE=test

API

Construct an environments.patch API request.

In this request:

  1. In the updateMask parameter, specify the config.softwareConfig.envVariables mask to replace all existing variables with the specified variables. Variables that you don't specify are deleted.

  2. In the request body, specify variables and their values:

    {
  "config": {
    "softwareConfig": {
      "envVariables": {
        "VAR_NAME": "VAR_VALUE"
      }
    }
  }
}

    Replace:

    • VAR_NAME with the name of the environment variable.
    • VAR_VALUE with the value of the environment variable.
    • To add more than one variable, add extra entries for variables to envVariables.

Example:

// PATCH https://composer.googleapis.com/v1/projects/example-project/
// locations/us-central1/environments/example-environment?updateMask=
// config.softwareConfig.envVariables
{
  "config": {
    "softwareConfig": {
      "envVariables": {
        "EXAMPLE_VARIABLE": "True",
        "ANOTHER_VARIABLE": "test"
      }
    }
  }
}

Terraform

The env_variables block in the software_config block specifies environment variables.

resource "google_composer_environment" "example" {
  name = "ENVIRONMENT_NAME"
  region = "LOCATION"

  config {

    software_config {

      env_variables = {
        VAR_NAME = "VAR_VALUE"
      }

    }
  }
}

Replace:

  • ENVIRONMENT_NAME with the name of the environment.
  • LOCATION with the region where the environment is located.
  • VAR_NAME with the name of the environment variable.
  • VAR_VALUE with the value of the environment variable.
  • To add more than one variable, add extra entries for variables to env_variables.

Example:

resource "google_composer_environment" "example" {
  name = "example-environment"
  region = "us-central1"

  config {

    software_config {

      env_variables = {
        EXAMPLE_VARIABLE = "True"
        ANOTHER_VARIABLE = "test"
      }
    }
  }
}

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