dispatch.yaml Configuration File

Region ID

The REGION_ID is an abbreviated code that Google assigns based on the region you select when you create your app. The code does not correspond to a country or province, even though some region IDs may appear similar to commonly used country and province codes. Including REGION_ID.r in App Engine URLs is optional for existing apps and will soon be required for all new apps.

To ensure a smooth transition, we are slowly updating App Engine to use region IDs. If we haven't updated your Google Cloud project yet, you won't see a region ID for your app. Since the ID is optional for existing apps, you don't need to update URLs or make other changes once the region ID is available for your existing apps.

Learn more about region IDs.

The dispatch.yaml allows you to override routing rules. You can use the dispatch.yaml to send incoming requests to a specific service (formerly known as modules) based on the path or hostname in the URL.

For more information, see How Requests are Routed.

An app can have only one dispatch.yaml file, and the routing rules in that file apply to all of the app's services and versions. The routing rules also apply to URLs that are used in a cron file.

Deploying the dispatch file

The dispatch.yaml file should reside in the same directory as your Go source code.

To deploy the dispatch.yaml file, use the following command. Before you deploy your dispatch file, you must ensure that all the services defined in that file have already been deployed to App Engine.

gcloud

Run the gcloud app deploy command from the directory that contains the dispatch.yaml:

gcloud app deploy dispatch.yaml

For more information about the deployment commands, see Deploying a Go 1.11 App.

Syntax

The root element in the dispatch.yaml file is dispatch: and contains a list of routing definitions that are specified by the following subelements.

The rules that you define in your dispatch file must use HTTP URL patterns that include the "." notation for separating subdomains. URLs defined with the HTTPS "-dot-" notation are not supported.

Dispatch rules are order dependent, and only the first rule that matches a URL will be applied.

Element Description
service

Specifies the name of the service that will handle the requests that match the url pattern. Note that services were previously called modules.

url

In the url element, you define the URL pattern within quotes, which can include the host name and URL path that are no longer than 100 characters. For the service element, you specify the name of the service that you want handling any incoming requests that match the URL pattern of the url element.

Tip: You can include glob patterns like the * wildcard character in the url element; however, those patterns can be used only before the host name and at the end of the URL path.

A URL pattern that can include the hostname and URL path. Glob characters can be used to match patterns. The Glob characters can be specified only at the beginning of the pattern and end of the pattern.

URL paths that begin with /_ah/ are not routed by the dispatch file.

Example

The following is a sample dispatch file that routes requests to https://simple-sample.uc.r.appspot.com and requests like https://simple-sample.uc.r.appspot.com/favicon.ico to the default service. All static content is served from the default service. Mobile requests like https://simple-sample.uc.r.appspot.com/mobile/ are routed to a mobile frontend, and worker requests like https://simple-sample.uc.r.appspot.com/work/ are routed to a static backend.

dispatch:
  # Default service serves the typical web resources and all static resources.
  - url: "*/favicon.ico"
    service: default

  # Default service serves simple hostname request.
  - url: "simple-sample.appspot.com/"
    service: default

  # Send all mobile traffic to the mobile frontend.
  - url: "*/mobile/*"
    service: mobile-frontend

  # Send all work to the one static backend.
  - url: "*/work/*"
    service: static-backend

If you prefer general routing rules that match many possible requests, you can define rules with wider scopes. For example:

# Send any path that begins with “simple-sample.appspot.com/mobile” to the mobile-frontend service.
- url: "simple-sample.appspot.com/mobile*"
  service: mobile-frontend

# Send any domain/sub-domain with a path that starts with “work” to the static backend service.
- url: "*/work*"
  service: static-backend

You can also write expressions that are more strict:

# Matches the path "/fun", but not "/fun2" or "/fun/other".
- url: "*/fun"
  service: mobile-frontend

# Matches the hostname "customer1.myapp.com", but not "1.customer1.myapp.com".
- url: "customer1.myapp.com/*"
  service: static-backend

Limits

The dispatch file can contain up to 20 routing rules. When specifying the URL string, neither the hostname nor the path can be longer than 100 characters.

Deleting all dispatch rules

To delete all dispatch rules:

  1. Edit the contents of the dispatch.yaml file to:

    dispatch: []
    
  2. Deploy the dispatch.yaml file to App Engine.