4. Local development with rover dev


Excited to start connecting cookware data directly to recipes? First, let's make sure we're set up for local development.

In this lesson, we will:

  • Review the development kit provides
  • Use rover dev to do local development with our

The GraphOS supergraph development kit

provides a supergraph development kit that helps developers build and play with within a architecture quickly and easily.

We've already been using parts of the development kit!

Sandbox is one such tool, a special mode of Apollo Studio that provides us with Explorer (the IDE we've been using to build and run queries against our locally-running ), a schema reference, , and diffs.

Though you didn't create them yourself, both recipes and kitchenware were bootstrapped using rover template, providing a starting point for a with JavaScript.

Note: Curious about other templates for different languages bootstrapping a new ? Check out rover template in the Apollo documentation.

The last piece of our development kit is rover dev.

Using rover dev

rover dev lets us start a local —right on your computer!—that can across one or more . Each subgraph can be run locally or remotely. It's a in our local development environment! This lets us implement and test changes before we publish them to .

To get started, we'll need the recipes running. If you haven't already, start the recipes locally by navigating to your copy of the repo and running npm run dev.


Next, let's start up the first rover dev process. This will start the local and we want it to use our locally-running recipes server as the first in the .

rover dev needs the following parameters:

rover dev \
--name {SUBGRAPH NAME} \
--url {ROUTING URL} \

The schema file parameter is optional. If the schema file isn't provided, will use on the instead. We'll see an example of this when we add the kitchenware later on.

Starting the first (main) rover dev process

Let's give it a try! Open up a new terminal window. Navigate to the recipes directory. Then, run the rover dev command with the appropriate values.

rover dev \
--name recipes \
--url http://localhost:4001 \
--schema ./schema.graphql

After running it, we'll get the following output:

⚠️ Do not run this command in production! ⚠️ It is intended for local development.
🛫 starting a session with the 'recipes' subgraph
🎶 composing supergraph with Federation v2.3.1
🚀 your supergraph is running! head to http://localhost:4000 to query your supergraph
👀 watching ./schema.graphql for changes

Awesome, looks like our is running at http://localhost:4000. Let's check it out!

Note: By default, rover dev runs the on port 4000. If you would prefer running it on a different port, you can add the additional flag --supergraph-port (or -p) and set it to a different value. Just make sure you're not using port 4001 because that's where the recipes is running!

In the browser, navigate to http://localhost:4000. We'll see Sandbox connected to the endpoint, ready for us to our local .

In the Documentation panel, we can see familiar-looking from our recipes . Test out a for a random recipe.

query GetRandomRecipe {
randomRecipe {
ingredients {

And we get our recipe data back! 🎉

This first rover dev process is also our main rover dev process. It's the process responsible for running the . If we stopped this process, the supergraph would stop running locally as well!

Starting the second rover dev process

Time to add the kitchenware into the mix! This subgraph is hosted remotely, so the rover dev command parameters will look a little different. This time, we'll omit the schema file path; will use to get all the details it needs instead.

Open up a new terminal window. If you're using VS Code, we recommend opening it in a split screen view so that both rover dev processes are side by side.

Let's run this command:

rover dev \
--name kitchenware \
--url https://poetic-plates-kitchenware-api.herokuapp.com/ \

Note: If you used a different port with the first rover dev command, then make sure you run this command with the same port! This ensures that both processes are able to communicate with each other.

After running the command, we should get the following output:

WARN: if you would like to watch '--schema ./schema.graphql' for changes instead of introspecting every second, re-run this command with the '--schema ./schema.graphql' argument
👂 polling https://poetic-plates-kitchenware-api.herokuapp.com/ every 1 second
🐤 adding the 'kitchenware' subgraph to the session
✅ successfully composed after adding the 'kitchenware' subgraph

Note the first line indicating that rover dev is using instead of watching for changes in a local file.

If you had both terminals side by side, you might have also noticed that the first rover dev process has two additional lines:

🎶 composing supergraph with Federation v2.3.1
✅ successfully composed after adding the 'kitchenware' subgraph

The addition of the new went without a hitch! We've just done the equivalent of what we did in lesson 3 when we added the kitchenware using Studio, but locally!

When we head back over to the on http://localhost:4000, we can see new were added, belonging to the kitchenware . And we can make the same we did in the last lesson, just to double check everything is working smoothly.

query SkilletAndRecipes($name: String) {
cookware(name: $name) {
recentlyAddedRecipes {

And under the Variables section:

"name": "cast iron skillet"

Run the query and... data! 🎉You can confirm the same data was returned in Studio as it is in Sandbox.

We're now free to make any changes we'd like to in the recipes , and see for ourselves how the would handle them. We can even spin up a whole new subgraph (maybe cookbooks? Chef information? Where to find the best ingredients?) and add it to our local .

This is your playground to explore in, to test new concepts, and dream up new features– all without impacting the production !


Which of the following does rover dev not do?

Key takeaways

  • The development kit includes the following: Sandbox, rover template and rover dev.
  • rover dev lets us start a local that can across one or more .
  • To use rover dev, we need each 's name, the URL where it's running, and (optionally) the path to the schema file. If the schema file is not provided, will use on the subgraph instead.
  • We can add however many we want to our local using rover dev.

Up next

We have everything we need to get started on our changes! Let's turn our focus back to that dream that connects data between a recipe and the cookware it uses. For this, we'll need to dive into the architecture and how the handles coordination across .


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