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When you set up a project containing multiple applications, all of your apps are served by a single router for the project. Each of your apps must have a name that’s unique within the project. To define specific routes for one of your apps, use this name. There are various ways you can define routes for multiple app projects. In this project, you have a CMS app, two frontend apps (one using Symfony and another using Gatsby), and a Mercure Rocks server app, defined as follows:
You don’t need to define a route for each app in the repository. If an app isn’t specified, then it isn’t accessible to the web. One good example of defining an app with no route is when you use Git submodules and want to use a source operation to update your submodules.You can also achieve the same thing by defining the app as a worker.
Depending on your needs, you could configure the router container using subdomains or using subdirectories.

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Define routes using subdomains

You could define routes for your apps as follows:
.upsun/config.yaml
routes:
  "https://mercure.{default}/":
    type: upstream
    upstream: "mercure:http"
  "https://{default}/":
    type: upstream
    upstream: "api:http"
So if your default domain is example.com, that means:
  • https://mercure.example.com/ is served by your Mercure Rocks app (mercure).
  • https://example.com/ is served by your Symfony frontend app (api).
Using a subdomain might double your network traffic, so consider using a path like https://{default}/api instead.

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Define routes using subdirectories

Alternatively, you could define your routes as follows:
.upsun/config.yaml
routes:
  "https://{default}/":
    type: upstream
    upstream: "api:http"
  "https://{default}/admin":
    type: upstream
    upstream: "admin:http"
Then you would need to configure each app’s web.locations property to match these paths: So if your default domain is example.com, that means:
  • https://example.com/ is served by your Symfony frontend app (api).
  • https://example.com/admin is served by your Admin app (admin).
Note that in this example, for the configuration of your admin app, you need to add the URL suffix /admin as both an index in the web.locations and a value for the passhtru setting. For a complete example, go to this project on GitHub.
Last modified on March 11, 2026