Set up server-side tagging with App Engine

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This guide explains how to:

  • Provision a tagging server on Google Cloud Platform (GCP) App Engine.
  • Upgrade the tagging server to handle live traffic.
  • Increase or decrease the number of servers that are running your Google Tag Manager container.


  1. You need a GCP account. If you don't have one, create a new GCP account.
  2. You need a GCP billing account. If you don't have one, create a GCP billing account (requires the Billing Account Creator role).
  3. You need the Project Creator and the Billing Account User role. Learn more about adding roles.

1. Provision a server

You can provision an App Engine service either automatically in Google Tag Manager or manually in Google Cloud.

Please select a provisioning method

Initial server configuration (testing)

The testing configuration is appropriate for exploring the product by sending small amounts of test traffic and using the Preview feature in Tag Manager. This configuration is an App Engine F1 instance class in the Standard environment and in most cases, you will not incur any costs.

2. Using App Engine in production

In production configuration, each server costs approximately $40 / month (USD). Each server is an App Engine instance with 1 vCPU, 0.5 GB memory, 10 GB disk in the Flexible environment.

See Managing App Engine costs to understand App Engine billing and how to configure billing alerts. We strongly recommend setting up a billing alert.

We recommend running a minimum of 3 servers to reduce the risk of data loss in case of a server outage. However, you may choose to run fewer (or more) servers. We expect that autoscaling 3-6 servers (the default) will handle 50-200 requests per second. The performance depends on the number of tags, and what those tags do.

To configure your tagging server:

  1. Open the Google Cloud Platform Cloud Shell.
  2. Set the Cloud Platform project in the Cloud Shell. Replace project ID with the GCP project ID that you noted earlier:
    gcloud config set project project ID
  3. To reconfigure the tagging server for a production environment, run the setup script below. Perform the following tasks:
    bash -c "$(curl -fsSL"
    1. Change the deployment type to production.
    2. Set up additional servers to serve production traffic. We recommend a minimum of three servers.

Optional: Disable App Engine request logging

By default, App Engine logs information about every single request (e.g. request path, query parameters, etc) that it receives. If your tagging server handles a lot of requests per month (e.g. greater than 1 million), those log messages may incur significant logging charges. To reduce or eliminate the logging charges, we recommend disabling the App Engine request logging.

To disable App Engine request logging:

  1. In Google Cloud platform, open the Logs Router. Make sure you're in the project that matches your container ID:
    screenshot of GCP project selector, showing a sample Tag Manager container
  2. For the Type: Cloud Logging bucket, Name: _Default line, select the overflow menu, then click Edit Sink.
  3. Under Sink destination, select logs bucket _Default.
  4. Under Choose logs to include in sink, add a new line. Enter the following rule to the existing inclusion filter:

  5. To also disable logging from the load balancer, add a new line and enter the following rule to the existing inclusion filter:

    NOT LOG_ID("requests")
  6. Click Update Sink button at the bottom

Now the App Engine requests will be excluded from logging. Check the Logs Explorer to ensure that new requests are not appearing in the logs.

3. Map the deployment to your custom domain

The default server-side tagging deployment is hosted on an App Engine domain. We recommend that you modify the deployment to use a subdomain of your website.

Map your website subdomain to your tagging server.

4. Add the server URL to Google Tag Manager

Now that you have a server, you need to make sure that Google Tag Manager knows it should use your server.

  1. Open Google Tag Manager.

  2. Click on the server container you want to point to your tagging server.

  3. Open your server container settings in the Admin tab > Container Settings.

  4. Click Add URL and paste your server URL.

  5. Save and go back to your workspace.

5. Validation

Now that you've set up your tagging server, make sure that it works as intended. In your Tag Manager workspace, click the Preview button. If the preview page loads, then everything is set up correctly.

Previewing multiple URLs

If you have mapped multiple domains to a single tagging server, make sure each URL is added to the container settings.

If you provided multiple URLs, all paths (the string after the domain name) must match.

Works Does not work
URL 1:
URL 2:
URL 1:
URL 2:

If multiple URLs are added, you will see an icon next to the Preview button that allows you to select the URL to preview.

Troubleshoot production deployment timeouts

When you run the setup script to create or reconfigure the tagging server, the script may time out. There are several reasons this could happen. The two most common are:

  1. Service accounts have incorrect permissions - The Compute Engine and App Engine service accounts are responsible for deploying and maintaining the production deployment. By default, they are preconfigured with the appropriate permissions. However, in some cases, an organization's policy may cause them to be incorrect.

    1. Navigate to the IAM & Admin page in the left-hand navigation bar in the Google Cloud console.
    2. Find the Compute Engine service account <project_number> and the App Engine service account <project_name>
    3. Both service accounts must have the Editor role. If either account does not have the Editor role, update the role by clicking the pencil icon on the right of the account, clicking the dropdown of the existing role, scrolling up to the top and clicking Project, then Editor.
  2. Insufficient quota - The production deployment consumes Compute Engine quota. If the project does not have enough quota, the deployment may time out while trying to provision resources.

    1. Navigate to the IAM & Admin page in the left-hand navigation bar in the Google Cloud console, then click the Quotas tab in the left-hand navigation bar.
    2. Near the top of the page, click the text box that says Filter table and type in Compute Engine API. Click the only result.
    3. Verify that all the quota statuses are within limit or have a green checkmark.
    4. Find and click into CPUs. Verify that the current usage plus the number of instances being deployed will still be below the limit for the deployment region.