Delve exposes a JSON-RPC API interface.
Note that this JSON-RPC interface is served over a streaming socket, not over HTTP.
Delve currently supports two versions of its API. By default a headless instance of dlv will serve APIv1 for backward compatibility with old clients, however new clients should use APIv2 as new features will only be made available through version 2. To select APIv2 use --api-version=2 command line argument.
Clients can also select APIv2 by sending a SetApiVersion request specifying APIVersion = 2 after connecting to the headless instance.
All the methods of the type service/rpc2.RPCServer can be called using JSON-RPC, the documentation for these calls is available on godoc.
Note that all exposed methods take one single input parameter (usually called args) of a struct type and also return a result of a struct type. Also note that the method name should be prefixed with RPCServer. in JSON-RPC.
Your client wants to set a breakpoint on the function main.main.
The first step will be calling the method FindLocation with Scope = api.EvalScope{ GoroutineID: -1, Frame: 0} and Loc = "main.main". The JSON-RPC request packet should look like this:
{"method":"RPCServer.FindLocation","params":[{"Scope":{"GoroutineID":-1,"Frame":0},"Loc":"main.main"}],"id":2}
the response packet will look like this:
{"id":2,"result":{"Locations":[{"pc":4199019,"file":"/home/a/temp/callme/callme.go","line":31,"function":{"name":"main.main","value":4198992,"type":84,"goType":0}}]},"error":null}
Now your client should call the method CreateBreakpoint and specify 4199019 (the pc field in the response object) as the target address:
{"method":"RPCServer.CreateBreakpoint","params":[{"Breakpoint":{"addr":4199019}}],"id":3}
if this request is successful your client will receive the following response:
{"id":3,"result":{"Breakpoint":{"id":1,"name":"","addr":4199019,"file":"/home/a/temp/callme/callme.go","line":31,"functionName":"main.main","Cond":"","continue":false,"goroutine":false,"stacktrace":0,"LoadArgs":null,"LoadLocals":null,"hitCount":{},"totalHitCount":0}},"error":null}