Working with subgraphs

A subgraph is a graph that contributes to the composition of a federated supergraph:

Rover commands that interact with subgraphs begin with rover subgraph.

Fetching a subgraph schema

These commands enable you to fetch the schema for a single subgraph in a federated graph. To instead fetch your gateway's composed supergraph schema, use the corresponding rover graph commands.

Fetching from Apollo Studio

This requires first authenticating Rover with Apollo Studio.

You can use Rover to fetch the current schema of any subgraph that belongs to a Studio graph and variant that Rover has access to.

Run the subgraph fetch command, like so:

rover subgraph fetch my-graph@my-variant --name accounts

The argument my-graph@my-variant in the example above is a graph ref that specifies the ID of the Studio graph you're fetching from, along with which variant you're fetching.

You can omit @ and the variant name. If you do, Rover uses the default variant, named current.

The --name option is also required. It must match the subgraph you're fetching the schema for.

Fetching via enhanced introspection

If you need to obtain a running subgraph's schema, you can use Rover to execute an enhanced introspection query on it. This is especially helpful if the subgraph doesn't define its schema via SDL (as is the case with graphql-kotlin).

Use the subgraph introspect command, like so:

rover subgraph introspect http://localhost:4001

The subgraph must be reachable by Rover. The subgraph does not need to have introspection enabled.

Unlike a standard introspection query, the result of rover subgraph introspect does include certain directives (specifically, directives related to federation like @key). This is possible because the command uses a separate introspection mechanism provided by the Apollo Federation specification.

Including headers

If the endpoint you're trying to reach requires HTTP headers, you can use the --header (-H) flag to pass key:value pairs of headers. If you have multiple headers to pass, provide the flag multiple times. If a header includes any spaces, the pair must be quoted.

rover subgraph introspect http://localhost:4001 --header "Authorization: Bearer token329r"

Output format

rover subgraph introspect http://localhost:4001\
  | rover subgraph publish my-graph@dev\
  --schema - --name accounts\
  --routing-url https://my-running-subgraph.com/api

By default, both subgraph fetch and subgraph introspect output fetched SDL to stdout. This is useful for providing the schema as input to other Rover commands:

rover subgraph introspect http://localhost:4000 | rover subgraph check my-graph --schema -

You can also save the output to a local .graphql file like so:

# Creates accounts-schema.graphql or overwrites if it already exists
rover subgraph introspect http://localhost:4000 > accounts-schema.graphql

For more on passing values via stdout, see Using stdout.

Listing subgraphs for a supergraph

This requires first authenticating Rover with Apollo Studio.

You can use the subgraph list to list all of a particular supergraph's available subgraphs in Apollo Studio:

rover subgraph list my-supergraph@dev

This command lists all subgraphs for the specified variant, including their routing URLs and when they were last updated (in local time). A link to view this information in Apollo Studio is also provided.

Subgraphs:

+----------+-------------- --------------+----------------------------+
| Name     | Routing Url                 | Last Updated               |
+----------+-----------------------------+----------------------------+
| reviews  | https://reviews.my-app.com  | 2020-10-21 12:23:28 -04:00 |
+----------+----------------------------------------+-----------------+
| books    | https://books.my-app.com    | 2020-09-20 13:58:27 -04:00 |
+----------+----------------------------------------+-----------------+
| accounts | https://accounts.my-app.com | 2020-09-20 12:23:36 -04:00 |
+----------+----------------------------------------+-----------------+
| products | https://products.my-app.com | 2020-09-20 12:23:28 -04:00 |
+----------+----------------------------------------+-----------------+

View full details at https://studio.apollographql.com/graph/my-graph/service-list

Publishing a subgraph schema to Apollo Studio

This requires first authenticating Rover with Apollo Studio.

You can use Rover to publish schema changes to a subgraph in one of your Apollo Studio supergraphs.

Use the subgraph publish command, like so:

rover subgraph publish my-supergraph@my-variant \
  --schema ./accounts/schema.graphql\
  --name accounts\
  --routing-url https://my-running-subgraph.com/api

The argument my-graph@my-variant in the example above is a graph ref that specifies the ID of the Studio graph you're publishing to, along with which variant you're publishing to.

You can omit @ and the variant name. If you do, Rover publishes the schema to the default variant, named current.

Options include:

Checking subgraph schema changes

Schema checks require a paid plan.

Before you publish subgraph schema changes to Apollo Studio, you can check those changes to confirm that you aren't introducing breaking changes to your application clients.

To do so, you can run the subgraph check command:

# using a schema file
rover subgraph check my-graph@my-variant --schema ./schema.graphql --name accounts

# using piped input to stdin
rover subgraph introspect http://localhost:4000 \
  | rover subgraph check my-graph@my-variant \
  --schema - --name accounts

As shown, arguments and options are similar to subgraph publish.

To configure the behavior of schema checks (such as the time range of past operations to check against), see the documentation for schema checks.