nomad: adding client deregister endpoint

nomad/client_endpoint.go

@@ -51,6 +51,27 @@ func (c *Client) Register(args *structs.RegisterRequest, reply *structs.GenericR
 	return nil
 }
 
+// Deregister is used to remove a client from the client. If a client should
+// just be made unavailable for scheduling, a status update is prefered.
 func (c *Client) Deregister(args *structs.DeregisterRequest, reply *structs.GenericResponse) error {
+	if done, err := c.srv.forward("Client.Deregister", args, args, reply); done {
+		return err
+	}
+	defer metrics.MeasureSince([]string{"nomad", "client", "deregister"}, time.Now())
+
+	// Verify the arguments
+	if args.NodeID == "" {
+		return fmt.Errorf("missing node ID for client deregistration")
+	}
+
+	// Commit this update via Raft
+	_, index, err := c.srv.raftApply(structs.DeregisterRequestType, args)
+	if err != nil {
+		c.srv.logger.Printf("[ERR] nomad.client: Deregister failed: %v", err)
+		return err
+	}
+
+	// Set the reply index
+	reply.Index = index
 	return nil
 }

nomad/client_endpoint_test.go

@@ -43,3 +43,46 @@ func TestClientEndpoint_Register(t *testing.T) {
 		t.Fatalf("index mis-match")
 	}
 }
+
+func TestClientEndpoint_Deregister(t *testing.T) {
+	s1 := testServer(t, nil)
+	defer s1.Shutdown()
+	codec := rpcClient(t, s1)
+	testutil.WaitForLeader(t, s1.RPC)
+
+	// Create the register request
+	node := mockNode()
+	reg := &structs.RegisterRequest{
+		Node:         node,
+		WriteRequest: structs.WriteRequest{Region: "region1"},
+	}
+
+	// Fetch the response
+	var resp structs.GenericResponse
+	if err := msgpackrpc.CallWithCodec(codec, "Client.Register", reg, &resp); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Deregister
+	dereg := &structs.DeregisterRequest{
+		NodeID:       node.ID,
+		WriteRequest: structs.WriteRequest{Region: "region1"},
+	}
+	var resp2 structs.GenericResponse
+	if err := msgpackrpc.CallWithCodec(codec, "Client.Deregister", dereg, &resp2); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if resp2.Index == 0 {
+		t.Fatalf("bad index: %d", resp2.Index)
+	}
+
+	// Check for the node in the FSM
+	state := s1.fsm.State()
+	out, err := state.GetNodeByID(node.ID)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if out != nil {
+		t.Fatalf("unexpected node")
+	}
+}