Federation 2 quickstart

Now that our project and tools are set up, we can start composing our supergraph schema with Apollo Studio.

Managed federation concepts

By composing our supergraph schema with Studio, we use a feature called managed federation. With managed federation, each of our subgraphs registers its schema with Apollo. Whenever a subgraph schema changes, Apollo composes a new supergraph schema.

Whenever composition succeeds, Apollo pushes an updated supergraph schema to Apollo Uplink, a special endpoint that gateways use to fetch their configuration:

Meanwhile, our gateway regularly polls Uplink for changes to its supergraph schema:

Whenever an update is available, the gateway downloads it and automatically begins using the new supergraph schema, without requiring a restart.

We strongly recommended managed federation for reducing downtime in your production supergraph. Let's set it up!

1. Register your subgraph schemas

Let's return to our gateway project. We can now use Rover's subgraph publish command to register our subgraph schemas with Apollo.

Run the following from your project directory, substituting your Studio graph's graph ref where indicated:

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rover subgraph publish YOUR_GRAPH_REF \
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  --routing-url https://flyby-locations-sub.herokuapp.com/ \
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  --schema ./locations.graphql \
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  --name locations

What's a graph ref?

A graph ref uniquely identifies a particular variant of a particular registered graph in Apollo Studio. Every graph ref is a string with the following format:

graph-id@variant

If you open your graph's README page in Apollo Studio, its graph ref is displayed as the top-level header of the page:

Every Studio graph is initially created with a single variant named current.

If the command is successful, you'll see output like the following:

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A new subgraph called 'locations' for the 'docs-example-graph@current' graph was created
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The gateway for the 'docs-example-graph' graph was updated with a new schema, composed from the updated 'locations' subgraph

Nice! If you open your graph's details in Studio now, you'll see types and fields from our locations subgraph listed in the Schema tab:

Now, let's do the same thing for our reviews subgraph, again substituting your graph ref where indicated:

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rover subgraph publish YOUR_GRAPH_REF \
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  --routing-url https://flyby-reviews-sub.herokuapp.com/ \
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  --schema ./reviews.graphql \
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  --name reviews

If you refresh the Schema tab in Studio, you'll now see types and fields from our reviews service as well.

Now that we've published our subgraph schemas, Apollo Studio automatically composes them into a supergraph schema! However, our gateway doesn't know how to fetch that schema from Apollo. We'll tackle that next.

2. Authenticate the gateway with Apollo Studio

It's time to enable our gateway to fetch its supergraph schema from Apollo. To do that, we'll need a graph API key that we set as the value of an environment variable.

1. Obtain a graph API key for your Studio graph by following these steps. Make sure to copy its value (for security, API keys are not visible in Studio after creation).

   If you have an Enterprise plan, set the API key's role to Contributor.

2. Create a new file named .env in your Node.js project folder.

   • Do not add the .env file to version control. If you're working in a Git repository, add .env to your .gitignore file.

3. Paste the following into .env:

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   APOLLO_KEY=your-api-key
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   APOLLO_GRAPH_REF=your-graph-id@your-variant

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   • Replace your-api-key with your graph API key.
   • Replace your-graph-id@your-variant with your graph's graph ref. (For details on graph refs, see Step 1.)

4. Add the dotenv Node.js library to your project:

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   npm install dotenv

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   This library takes care of reading environment variable values from your .env file.

5. Add the following line to the very top of index.js:

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   require('dotenv').config()

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6. Start up your gateway with node index.js. This time there's no error, and you'll see output similar to the following:

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   Apollo usage reporting starting! See your graph at https://studio.apollographql.com/graph/docs-example-graph@current/
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   🚀 Gateway ready at http://localhost:4000/

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We can quickly open our browser to studio.apollographql.com/sandbox to explore our composed schema in Apollo Sandbox:

While we're here, you can even execute some test queries against the supergraph.

Moving forward

Nice work! We've registered two subgraph schemas with Apollo, and we have a federated gateway that then fetches the composed supergraph schema.

If we now register changes to one of our subgraph schemas, our running gateway automatically fetches the corresponding changes to the supergraph schema (assuming composition succeeds).

Next, let's look at how to use the Rover CLI to compose a supergraph schema locally or in a CI environment. Go to part 3.