Access the Apache Airflow web user interface

Cloud Composer 1 | Cloud Composer 2 | Cloud Composer 3

Apache Airflow includes a web user interface (UI) that you can use to manage workflows (DAGs), manage the Airflow environment, and perform administrative actions. For example, you can use the web interface to review the progress of a DAG, set up a new data connection, or review logs from previous DAG runs.

Airflow web server

Each Cloud Composer environment has a web server that runs the Airflow web interface. The web server is a part of Cloud Composer environment architecture.

The web server parses the DAG definition files in the dags/ folder and must be able to access a DAG's data and resources to load the DAG and serve HTTP requests.

The web server refreshes the DAGs every 60 seconds, which is the default worker_refresh_interval in Cloud Composer. A web server error can occur if the web server cannot parse all the DAGs within the refresh interval.

Exceeding 60 seconds to load DAGs can occur if there are a large number of DAG files or there is a non-trivial workload to load the DAG files. To ensure that web server remains accessible regardless of DAG load time, you can configure asynchronous DAG loading to parse and load DAGs in the background at a pre-configured interval (available in composer-1.7.1-airflow-1.10.2 and later versions). This configuration can also reduce DAG refresh time.

Other than exceeding the worker refresh interval, the web server can gracefully handle DAG loading failures in most cases. DAGs that cause the web server to crash or exit might cause errors to be returned in the browser. For information, see Troubleshooting DAGs.

If you continue to experience web server issues due to DAG parsing, we recommend that you use asynchronous DAG loading.

Before you begin

  • You must have a role that can view Cloud Composer environments. For more information, see Access control.

  • During the environment creation, Cloud Composer configures the URL for the web server that runs the Airflow web interface. The URL is non-customizable.

  • The Airflow UI Access Control (Airflow Role-Based Access Control) feature for the Airflow web interface is supported for Cloud Composer environments running Composer version 1.13.4 or later, Airflow version 1.10.10 or later, and Python 3.

Accessing the Airflow web interface

The Airflow web server service is deployed to the appspot.com domain and provides access to the Airflow web interface. Cloud Composer 1 provides access to the interface based on user identities and IAM policy bindings defined for users. Cloud Composer 1 uses Identity-Aware Proxy for this purpose.

After creating a new Cloud Composer environment, it takes up to 25 minutes for the web interface to finish hosting and become accessible.

Accessing the web interface from the Google Cloud console

To access the Airflow web interface from the Google Cloud console:

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

    Go to Environments

  2. In the Airflow webserver column, follow the Airflow link for your environment.

  3. Log in with the Google account that has the appropriate permissions.

Limiting access to the Airflow web server

Composer environments let you limit access to the Airflow web server:

  • You can block all access, or allow access from specific IPv4 or IPv6 external IP ranges.
  • It's not possible to configure the allowed IP ranges using private IP addresses.

Retrieving the web interface URL via the gcloud command-line tool

You can access the Airflow web interface from any web browser. To get the URL for the web interface, enter the following gcloud command:

gcloud composer environments describe ENVIRONMENT_NAME \
  --location LOCATION

Replace the following:

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

The gcloud command shows the properties of a Cloud Composer environment, including the URL for the web interface. The URL is listed as airflowUri.

config:
  airflowUri: https://example-tp.appspot.com

Configuring asynchronous DAG loading

When asynchronous DAG loading is enabled, the Airflow web server creates a new process. This process loads DAGs in the background, sends newly loaded DAGs on intervals defined by the dagbag_sync_interval option, and then sleeps.

The process wakes up periodically to reload DAGs, the interval is defined by the collect_dags_interval option.

To enable asynchronous DAG loading:

  1. Disable DAG serialization. Asynchronous DAG loading cannot be used with DAG serialization. Using async_dagbag_loader and store_serialized_dags Airflow configuration options produces HTTP 503 errors and breaks your environment.

  2. Override the following Airflow configuration options:

    Section Key Value Notes
    webserver async_dagbag_loader True The default is False.
    webserver collect_dags_interval 30 The default is 30. Use a smaller value for faster refreshes.
    webserver dagbag_sync_interval 10 The default is 10.
    webserver worker_refresh_interval 3600 The default is 60. With asynchronous DAG loading, you can use a longer refresh interval.

Restarting the web server

When debugging or troubleshooting Cloud Composer environments, some issues may be resolved by restarting the Airflow web server. You can restart the web server using the restartWebServer API or the restart-web-server gcloud command:

gcloud beta composer environments restart-web-server ENVIRONMENT_NAME \
  --location=LOCATION

Configuring web server network access

The Airflow web server access parameters don't depend on the type of your environment. Instead, you configure web server access separately. For example, a Private IP environment can still have the Airflow UI accessible from the internet.

It is not possible to configure the allowed IP ranges using private IP addresses.

Console

  1. In the 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 configuration tab.

  4. In the Network configuration section, find the Web server access control item and click Edit.

  5. In the Web server network access control dialog:

    • To provide access to the Airflow web server from all IP addresses, select Allow access from all IP addresses.

    • To restrict access only to specific IP ranges, select Allow access only from specific IP addresses. In the IP range field, specify an IP range in the CIDR notation. In the Description field, specify an optional description for this range. If you want to specify more than one range, click Add IP range.

    • To forbid access for all IP addresses, select Allow access only from specific IP addresses and click Delete item next to the empty range entry.

gcloud

When you update an environment, the following arguments control web server access parameters:

  • --web-server-allow-all provides access to Airflow from all IP addresses. This is the default option.

  • --web-server-allow-ip restricts access only to specific source IP ranges. To specify several IP ranges, use this argument multiple times.

  • --web-server-deny-all forbids access for all IP addresses.

gcloud composer environments update ENVIRONMENT_NAME \
    --location LOCATION \
    --web-server-allow-ip ip_range=WS_IP_RANGE,description=WS_RANGE_DESCRIPTION

Replace the following:

  • ENVIRONMENT_NAME: the name of your environment.
  • LOCATION: the region where the environment is located.
  • WS_IP_RANGE: the IP range, in the CIDR notation, that can access the Airflow UI.
  • WS_RANGE_DESCRIPTION: the description of the IP range.

Example:

gcloud composer environments update example-environment \
    --location us-central1 \
    --web-server-allow-ip ip_range=192.0.2.0/24,description="office net 1" \
    --web-server-allow-ip ip_range=192.0.4.0/24,description="office net 3"

API

  1. Construct an [environments.patch][api-patch] API request.

  2. In this request:

    1. In the updateMask parameter, specify the config.webServerNetworkAccessControl mask.

    2. In the request body, specify how Airflow task logs must be saved:

      • To provide access to Airflow from all IP addresses, specify an empty config element (the webServerNetworkAccessControl element must not be present).

      • To restrict access only to specific IP ranges, specify one or more ranges in allowedIpRanges.

      • To forbid access for all IP addresses, specify an empty webServerNetworkAccessControl element. The webServerNetworkAccessControl element must be present, but must not contain an allowedIpRanges element.

{
  "config": {
    "webServerNetworkAccessControl": {
      "allowedIpRanges": [
        {
          "value": "WS_IP_RANGE",
          "description": "WS_RANGE_DESCRIPTION"
        }
      ]
    }
  }
}

Replace the following:

  • WS_IP_RANGE: the IP range, in the CIDR notation, that can access the Airflow UI.
  • WS_RANGE_DESCRIPTION: the description of the IP range.

Example:

// PATCH https://composer.googleapis.com/v1/projects/example-project/
// locations/us-central1/environments/example-environment?updateMask=
// config.webServerNetworkAccessControl

{
  "config": {
    "webServerNetworkAccessControl": {
      "allowedIpRanges": [
        {
          "value": "192.0.2.0/24",
          "description": "office net 1"
        },
        {
          "value": "192.0.4.0/24",
          "description": "office net 3"
        }
      ]
    }
  }
}

Terraform

In the allowed_ip_range block, in the web_server_network_access_control specify IP ranges that can access web server.

resource "google_composer_environment" "example" {
  provider = google-beta
  name = "ENVIRONMENT_NAME"
  region = "LOCATION"

  config {

    web_server_network_access_control {

      allowed_ip_range {
        value = "WS_IP_RANGE"
        description = "WS_RANGE_DESCRIPTION"
      }

    }

  }
}

Replace:

  • WS_IP_RANGE with the IP range, in the CIDR notation, that can access Airflow UI.
  • WS_RANGE_DESCRIPTION with the description of the IP range.

Example:

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

  config {

    web_server_network_access_control {
      allowed_ip_range {
        value = "192.0.2.0/24"
        description = "office net 1"
      },
      allowed_ip_range {
        value = "192.0.4.0/24"
        description = "office net 3"
      }

    }
}

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