graphql.execution.instrumentation.Instrumentation interface allows you to inject code that can observe the
execution of a query and also change the runtime behaviour.
The primary use case for this is to allow say performance monitoring and custom logging but it could be used for many different purposes.
When you build the
Graphql object you can specify what
Instrumentation to use (if any).
An implementation of
Instrumentation needs to implement the “begin” step methods that represent the execution of a graphql query.
Each step must give back a non null
graphql.execution.instrumentation.InstrumentationContext object which will be called back
when the step completes, and will be told that it succeeded or failed with a Throwable.
The following is a basic custom
Instrumentation that measures overall execution time and puts it into a stateful object.
You can combine multiple
Instrumentation objects together using the
graphql.execution.instrumentation.ChainedInstrumentation class which
accepts a list of
Instrumentation objects and calls them in that defined order.
graphql.execution.instrumentation.tracing.TracingInstrumentation is an
Instrumentation implementation that creates tracing information
about the query that is being executed.
It follows the Apollo proposed tracing format defined at
A detailed tracing map will be created and placed in the
extensions section of the result.
So given a query like
It would return a result like
graphql.execution.instrumentation.fieldvalidation.FieldValidationInstrumentation is an
Instrumentation implementation that
can be used to validate fields and their arguments before query execution. If errors are returned during this process then
the query execution is aborted and the errors will be in the query result.
You can make you own custom implementation of
FieldValidation or you can use the
to add simple per field checks rules.