rpc: set the deregistration eval priority to the job priority.

.changelog/11426.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+rpc: Set the job deregistration eval priority to the job priority
+```

nomad/job_endpoint.go

@@ -829,12 +829,26 @@ func (j *Job) Deregister(args *structs.JobDeregisterRequest, reply *structs.JobD
 	// priority even if the job was.
 	now := time.Now().UnixNano()
 
+	// Set our default priority initially, but update this to that configured
+	// within the job if possible. It is reasonable from a user perspective
+	// that jobs with a higher priority have their deregister evaluated before
+	// those of a lower priority.
+	//
+	// Alternatively, the previous behaviour was to set the eval priority to
+	// the default value. Jobs with a lower than default register priority
+	// would therefore have their deregister eval priorities higher than
+	// expected.
+	priority := structs.JobDefaultPriority
+	if job != nil {
+		priority = job.Priority
+	}
+
 	// If the job is periodic or parameterized, we don't create an eval.
 	if job == nil || !(job.IsPeriodic() || job.IsParameterized()) {
 		eval = &structs.Evaluation{
 			ID:          uuid.Generate(),
 			Namespace:   args.RequestNamespace(),
-			Priority:    structs.JobDefaultPriority,
+			Priority:    priority,
 			Type:        structs.JobTypeService,
 			TriggeredBy: structs.EvalTriggerJobDeregister,
 			JobID:       args.JobID,

nomad/job_endpoint_test.go

@@ -3825,6 +3825,56 @@ func TestJobEndpoint_BatchDeregister_ACL(t *testing.T) {
 	require.NotEqual(validResp2.Index, 0)
 }
 
+func TestJobEndpoint_Deregister_Priority(t *testing.T) {
+	t.Parallel()
+	requireAssertion := require.New(t)
+
+	s1, cleanupS1 := TestServer(t, func(c *Config) {
+		c.NumSchedulers = 0 // Prevent automatic dequeue
+	})
+	defer cleanupS1()
+	codec := rpcClient(t, s1)
+	testutil.WaitForLeader(t, s1.RPC)
+	fsmState := s1.fsm.State()
+
+	// Create a job which a custom priority and register this.
+	job := mock.Job()
+	job.Priority = 90
+	err := fsmState.UpsertJob(structs.MsgTypeTestSetup, 100, job)
+	requireAssertion.Nil(err)
+
+	// Deregister.
+	dereg := &structs.JobDeregisterRequest{
+		JobID: job.ID,
+		Purge: true,
+		WriteRequest: structs.WriteRequest{
+			Region:    "global",
+			Namespace: job.Namespace,
+		},
+	}
+	var resp structs.JobDeregisterResponse
+	requireAssertion.Nil(msgpackrpc.CallWithCodec(codec, "Job.Deregister", dereg, &resp))
+	requireAssertion.NotZero(resp.Index)
+
+	// Check for the job in the FSM which should not be there as it was purged.
+	out, err := fsmState.JobByID(nil, job.Namespace, job.ID)
+	requireAssertion.Nil(err)
+	requireAssertion.Nil(out)
+
+	// Lookup the evaluation
+	eval, err := fsmState.EvalByID(nil, resp.EvalID)
+	requireAssertion.Nil(err)
+	requireAssertion.NotNil(eval)
+	requireAssertion.EqualValues(resp.EvalCreateIndex, eval.CreateIndex)
+	requireAssertion.Equal(job.Priority, eval.Priority)
+	requireAssertion.Equal(job.Type, eval.Type)
+	requireAssertion.Equal(structs.EvalTriggerJobDeregister, eval.TriggeredBy)
+	requireAssertion.Equal(job.ID, eval.JobID)
+	requireAssertion.Equal(structs.EvalStatusPending, eval.Status)
+	requireAssertion.NotZero(eval.CreateTime)
+	requireAssertion.NotZero(eval.ModifyTime)
+}
+
 func TestJobEndpoint_GetJob(t *testing.T) {
 	t.Parallel()