Local Subgraph Development
Use the Rover CLI to run a local supergraph
While you're working on changes to one of your subgraphs, you can run a version of your entire supergraph locally in your development environment. To do this, you use the rover dev
command.
The rover dev
command monitors each of your subgraph schemas (either via server introspection or by watching a .graphql
file). Whenever it detects a change, it automatically recomposes your router's supergraph schema and raises any errors that might occur. This enables you iterate quickly on schema changes.
Starting your router
You run rover dev
once for each subgraph in your supergraph. The first time you run it, Rover spins up a router on your local machine.
Try running rover dev
with an example subgraph like so:
rover dev --url https://flyby-locations-sub.herokuapp.com/ --name locations
You'll see output like the following:
WARN: could not detect a schema in the current working directory. to watch a schema, pass the `--schema <PATH>` argument👂 polling https://flyby-locations-sub.herokuapp.com/ every 1 second⚠️ Do not run this command in production! ⚠️ It is intended for local development.🛫 starting a session with the 'locations' subgraph🎶 composing supergraph with Federation v2.1.2🚀 your supergraph is running! head to http://localhost:3000 to query your supergraph
You can now open http://localhost:3000
in your browser and run test queries against your local router using the Explorer!
You can replace the example subgraph URL and name in the above command with the details for your own subgraph. You can provide a remote URL or a localhost
URL.
Adding a subgraph
To add a subgraph to your local supergraph, run rover dev
again in a separate terminal window.
You can add a subgraph to this article's example supergraph with the following command:
rover dev --url https://flyby-reviews-sub.herokuapp.com/ --name reviews
This command's output is similar to the output for the initial execution, but it includes a line like the following:
🐤 adding the 'reviews' subgraph to the session
This indicates that rover dev
has identified your existing supergraph session and is adding this subgraph to it.
Now if you run test queries in the Explorer, you'll see that they can include fields from both the locations
and reviews
subgraphs!
Ending a rover dev
session
To shut down your local supergraph, use CTRL+C
to stop the first rover dev
process you started. This automatically terminates all secondary rover dev
processes that are part of the same session.
ⓘ NOTE
If you stop a secondary rover dev
process, your session remains active, and the router's schema is automatically updated to reflect the removed subgraph.
Command options
For more details on rover dev
options, see the Rover documentation.