What Is GraphQL? A Query Language for APIs

GraphQL is an API query language where the client describes exactly the fields it wants and the server returns just that data, usually through a single endpoint.

Instead of many fixed REST endpoints, GraphQL exposes one endpoint and a typed schema. Clients send a query naming the precise fields they need, and the server responds with matching data. Some CI integrations, including parts of the GitHub API, are GraphQL, so it helps to know how it differs from REST.

One endpoint, flexible queries

A GraphQL server typically accepts POST requests at a single URL. The body contains a query that selects fields across related objects, letting the client fetch nested data in one round trip instead of several.

Schema and types

GraphQL is strongly typed. The schema declares every object, field, and operation, so clients and tools can validate queries before sending them and discover the API by introspection.

Queries, mutations, subscriptions

Queries read data.
Mutations create or change data.
Subscriptions stream updates over a persistent connection.

Error handling is different

GraphQL often returns HTTP 200 even when a field errors, placing problems in an errors array in the body. A pipeline that only checks the status code can miss a partial failure, so it must inspect the response body too.

GraphQL in CI/CD

Automation may query a GraphQL API to fetch pull request data, manage releases, or read deployment status in one efficient call. The single-endpoint design keeps network round trips low, which matters for slow or rate-limited runs.

Transient failures still apply

The network underneath GraphQL is still HTTP, so timeouts and resets happen. Retrying a read query after a blip is safe, while a mutation may not be idempotent. Latchkey runners auto-retry transient transport failures, but your code should still guard non-idempotent mutations.

Key takeaways

GraphQL uses one endpoint and a typed schema to return exactly the fields requested.
Errors can appear in the response body even on a 200, so check the payload.
Reads are safe to retry; mutations may not be idempotent.