Adding a remote schema¶
Table of contents
Introduction¶
Follow the steps below to merge your remote schema with the GraphQL engine’s auto-generated schema.
Step 0: Write a custom GraphQL server¶
If you already have a functional GraphQL server that meets your requirements, you can skip this step.
You need to create a custom GraphQL server with a schema and corresponding resolvers that solve your use case
You can use any language/framework of your choice to author this server and deploy it anywhere. A great way to get started is to use one of our boilerplates
Step 1: Merge remote schema¶
The following details need to be specified for merging a remote schema:
Remote Schema name: an alias for the remote schema that must be unique on an instance of the GraphQL engine.
GraphQL server URL: the endpoint at which your remote GraphQL server is available. This value can be entered manually or by specifying an environment variable that contains this information.
Headers: configure the headers to be sent to your custom GraphQL server:
Toggle forwarding all headers sent by the client (when making a GraphQL query) to your remote GraphQL server.
Send additional headers to your remote server - these can be static header name-value pairs; and/or pairs of “header name-environment variable name”. You can specify the value of the header to be picked up from the environment variable.
Example: Let’s say your remote GraphQL server needs a
X-Api-Key
as a header. As this value contains sensitive data (like API key in this example), you can configure the name of an environment variable which will hold the value. This environment variable needs to be present when you start the GraphQL engine. When Hasura sends requests to your remote server, it will pick up the value from this environment variable.
Head to the Remote Schemas
tab of the console and click on the Add
button on the left sidebar.
Add the required details and click on the Add Remote Schema
button to merge the remote schema.
To add a remote schema, edit the remote_schemas.yaml
file in the metadata
directory as in this example:
- name: my-remote-schema
definition:
url: https://graphql-pokemon.now.sh/
timeout_seconds: 60
forward_client_headers: true
Apply the metadata by running:
hasura metadata apply
You can add a remote schema by using the add_remote_schema metadata API:
POST /v1/query HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin
{
"type": "add_remote_schema",
"args": {
"name": "my-remote-schema",
"definition": {
"url": "https://graphql-pokemon.now.sh/",
"forward_client_headers": true,
"timeout_seconds": 60
}
}
}
Note
If you are running Hasura using Docker, ensure that the Hasura Docker container can reach the server endpoint. See this page for Docker networking.
If you are adding the URL using env variable, then run the Hasura docker container with the env variable added
during docker run. Example -e REMOTE_SCHEMA_ENDPOINT=http://host.docker.internal:4000/mycustomgraphql
.
Using environment variables
If you are using environment variables in the remote schema configuration - either for URL or headers - the environment variables need to be present with valid values when adding the remote schema i.e. the GraphQL engine should be started with these environment variables.
Step 2: Make queries to the remote server from Hasura¶
GraphiQL
tab and make queries to your remote server from Hasura./v1/graphql
).Points to remember¶
Remote schema fields nomenclature¶
- Top-level field names need to be unique across all merged schemas (case-sensitive match).
- Types with the exact same name and structure will be merged. But types with the same name but different structure will result in type conflicts.
Schema refreshing¶
A remote server’s GraphQL schema is cached and refreshed only when user explicitly reloads the remote schema.
Remote Schemas -> [remote_schema_name] -> Details
and click the Reload
button.Current limitations¶
- Subscriptions on remote GraphQL servers are not supported.
Extending the auto-generated GraphQL schema fields¶
For some use cases, you may need to extend the GraphQL schema fields exposed by the Hasura GraphQL engine (and not merely add new fields as we have done here) with a custom schema/server. To support them, you can use community tooling to write your own client-facing GraphQL gateway that interacts with the GraphQL engine.
Note
Adding an additional layer on top of the Hasura GraphQL engine significantly impacts the performance provided by it out of the box (by as much as 4x). If you need any help with remodelling these kinds of use cases to use the built-in remote schemas feature, please get in touch with us on Discord.
Additional Resources
Data Federation with Hasura - Watch Webinar.