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The Rover dev Command

Run your supergraph in your local dev environment


A supergraph is an architecture consisting of multiple APIs (subgraphs) and a graph router that runs in front of them:

Supergraph
Graph Router
Subgraph A
Subgraph B
Clients

While you're making local changes to an individual , you can use the rover dev command to start a local instance and test out the effects of those changes on your entire .

⚠️ CAUTION

Don't run rover dev in production. It's for local development only.

Whenever you add, modify, or remove a subgraph from your local supergraph, automatically re-composes your individual into a unified , which your local router session automatically begins using.

Starting a router session

To use rover dev, you need at least one running GraphQL API (subgraph). Rover can obtain a subgraph's schema via (either standard or federated introspection), or you can provide a local schema file.

Here's an example rover dev command that points to a locally running subgraph and provides its schema via a local file:

Example command
rover dev --name products --schema ./products.graphql --url http://localhost:4000

NOTE

You don't have to provide a locally running subgraph. You can point to any GraphQL endpoint that your local environment can reach. You can even mix and match local and remote subgraphs, which is helpful for testing local changes against your staging subgraphs.

When you start your first rover dev process:

  1. Rover obtains the you provide (via either introspection or file path).
  2. Rover composes a supergraph schema from the subgraph schema.
  3. Rover starts a locally running router session and provides it the supergraph schema.
  4. Rover starts watching the provided subgraph schema for changes (via either introspection or file), and it recomposes the supergraph schema whenever it detects a change. This automatically reloads the router.

After you start a local router session with your first rover dev process, you can run additional rover dev processes to add subgraphs to the session.

Starting a session with multiple subgraphs

If you have a standard set of that you're always developing with, you can create a supergraph config file to add all of them to your local router session with a single rover dev command.

For example, this supergraph.yaml file provides the necessary details for two subgraphs:

supergraph.yaml
federation_version: =2.4.7
subgraphs:
products:
routing_url: http://localhost:4000
schema:
file: ./products.graphql # Schema provided via file
reviews:
schema:
subgraph_url: http://localhost:4001 # Schema provided via introspection, routing_url can be omitted
users:
# routing_url: <Optional, pulled from GraphOS registry by default>
schema: # Schema downloaded from GraphOS registry, does not poll for updates
graphref: mygraph@current
subgraph: actors

You provide this file to rover dev like so:

rover dev --supergraph-config supergraph.yaml

If you do, a router session starts with one of the subgraphs listed, then adds the remaining subgraphs one at a time (order is undefined). Because of this, you might observe errors during intermediate steps.

Providing a supergraph.yaml file also enables you to take advantage of other config options, such as introspection_headers.

If you start your session with a config file, you can still add other subgraphs individually. However, you can't provide another config file.

Adding a subgraph to a session

After you start a router session with your first rover dev command, you can then add other subgraphs to that same session.

To add a subgraph, open a new terminal window and run rover dev again, this time providing the details of the subgraph to add. For example, this command adds a users subgraph:

rover dev --name users --url http://localhost:4002

Rover detects your existing session and attaches this new process to it.

When you add a new subgraph to a session, Rover recomposes the supergraph schema and updates the router so you can all added subgraphs via the single router endpoint.

NOTE

Rover uses the port of the running router to identify an existing session. If you specify a custom port via --supergraph-port or --router-config, make sure to specify the same port for all rover dev processes that you want to attach to the same session.

Stopping a session

If you stop your initial rover dev process (by pressing CTRL+C), it shuts down the local router session. This also shuts down any secondary rover dev processes attached to that same session.

Removing a subgraph

If you stop a secondary rover dev process (by pressing CTRL+C), its associated router session recomposes its supergraph schema without the corresponding subgraph and reloads the router.

Health check

By default, the router's health check endpoint is disabled in rover dev. You can enable it again by enabling it in a router configuration YAML file and passing it to rover dev via the --router-config described in the following section.

Configuring the router

To configure advanced router functionality like CORS settings or header passthrough for subgraphs, you can pass a valid router configuration YAML file to rover dev via the --router-config <ROUTER_CONFIG_PATH> argument.

Note that only the main rover dev process uses this router configuration file when starting the router. If you specify a different listen address with supergraph.listen, all other rover dev processes need to pass the same values to --supergraph-port and --supergraph-address, and/or pass the same router configuration file path via --router-config.

Enterprise features

If you want to use enterprise router features, you must provide both:

  1. A via the APOLLO_GRAPH_REF environment variable.
  2. A graph API key either via the APOLLO_KEY environment or by configuring credentials in Rover.

Federation 2 ELv2 license

The first time you use Federation 2 composition on a particular machine, Rover prompts you to accept the terms and conditions of the ELv2 license. On future invocations, Rover remembers that you already accepted the license and doesn't prompt you again (even if you update Rover).

The ELv2-licensed plugins, supergraph (built from this source) and router (built from this source) are installed to ~/.rover/bin if you installed with the curl | sh installer, and to ./node_modules/.bin/ if you installed with npm.

Versioning

By default, rover dev uses a recent version of the router and composition to use for you. This is currently configured in the Rover GitHub repo, however, you can override these by setting the environment variables APOLLO_ROVER_DEV_COMPOSITION_VERSION=2.0.0 and/or APOLLO_ROVER_DEV_ROUTER_VERSION=1.0.0. By default, rover dev will always use a composition library with a major version of v2, and a router with a major version of v1. If you already have the plugins installed, you can pass --skip-update to rover dev in order to keep the plugins at the same version.

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