open-nomad/contributing/checklist-rpc-endpoint.md

New RPC Endpoint Checklist

Prefer adding a new message to changing any existing RPC messages.

Code

• Request struct and *RequestType constant in nomad/structs/structs.go. Append the constant, old constant values must remain unchanged

• In nomad/fsm.go, add a dispatch case to the switch statement in (n *nomadFSM) Apply

  • *nomadFSM method to decode the request and call the state method

• State method for modifying objects in a Txn in nomad/state/state_store.go

  • nomad/state/state_store_test.go

• Handler for the request in nomad/foo_endpoint.go

  • RPCs are resolved by matching the method name for bound structs net/rpc
  • Check ACLs for security, list endpoints filter by ACL
  • Register new RPC struct in nomad/server.go
  • Check ACLs to enforce security

• Wrapper for the HTTP request in command/agent/foo_endpoint.go

  • Backwards compatibility requires a new endpoint, an upgraded client or server may be forwarding this request to an old server, without support for the new RPC
  • RPCs triggered by an internal process may not need support
  • Check ACLs as an optimization

• nomad/core_sched.go sends many RPCs

  • ServersMeetMinimumVersion asserts that the server cluster is upgraded, so use this to guard sending the new RPC, else send the old RPC
  • Version must match the actual release version!

Docs

• Changelog
• Metrics
• API docs for RPCs with an HTTP endpoint, include ACLs, params, and example response body.