Chapter 2. GraphQL API

You can use an HTTP client, such as HTTPie, to interact with the GraphQL API for generating custom queries.

When using the API to create a query, you must specify specific values for data types and fields, so that a function can use these values to accurately locate the data you require.

Consider a use case where you could automate a workflow that performs multiple operations in a single query. As an example, an HTTPie client request could send a query to Cryostat so that Cryostat could perform the following tasks:

The following examples demonstrate using the HTTP client to interact with the GraphQL API for generating a simple query and a complex query on Cryostat data.

https :8181/api/v1/targets

$ https :8181/api/v1/targets
HTTP/1.1 200 OK
content-encoding: gzip
content-length: 223
content-type: application/json

 {
	targetNodes {
    		name
    		nodeType
    		labels
    		target {
        		alias
        		serviceUri
    		}
	}
}

The previous example sets specific values for the targetNodes element, such as name. After you run the query, the query returns a list of any target JVMs that match the criteria specified.

https -v :8181/api/v2.2/graphql query=@graphql/target-nodes-query.graphql

$ https -v :8181/api/v2.2/graphql query=@graphql/target-nodes-query.graphql
POST /api/v2.2/graphql HTTP/1.1
Accept: application/json, /;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 171
Content-Type: application/json
Host: localhost:8181
User-Agent: HTTPie/2.6.0

 {
environmentNodes(filter: { name: "<application_pod_name>" }) {
    		descendantTargets {
        		doStartRecording(recording: {
            		name: "myrecording",
            	template: "Profiling",
            	templateType: "TARGET",
     		       	duration: 30
          	 	}) {
          			name
          			state
        		}
    		}
	}
}

The previous example sets the following specific values for the environmentNodes element, and the example does not return JVM target applications:

After you run the query, the query returns information about the JFR recording that you started, such as a list of active application nodes.

For Red Hat OpenShift, this query would return Deployment and DeploymentConfig API objects, and pods that interact with Cryostat.

The complex query demonstrates how the GraphQL API can perform a single API request that returns any JVM objects that interact with Cryostat and Red Hat OpenShift. The API request then starts a JFR recording on those returned objects.