Add preserve-resources flag (#26841)

* Add preserve-resources flag when registering a job

* Add preserve-resources flag to website docs

* Add changelog

* Update tests, docs

* Preserve counts & resources in fsm

* Update doc

* Update preservation of resources/count to happen in StateStore

api/jobs.go

@@ -120,12 +120,13 @@ func (j *Jobs) Validate(job *Job, q *WriteOptions) (*JobValidateResponse, *Write
 
 // RegisterOptions is used to pass through job registration parameters
 type RegisterOptions struct {
-	EnforceIndex   bool
-	ModifyIndex    uint64
-	PolicyOverride bool
-	PreserveCounts bool
-	EvalPriority   int
-	Submission     *JobSubmission
+	EnforceIndex      bool
+	ModifyIndex       uint64
+	PolicyOverride    bool
+	PreserveCounts    bool
+	PreserveResources bool
+	EvalPriority      int
+	Submission        *JobSubmission
 }
 
 // Register is used to register a new job. It returns the ID
@@ -152,6 +153,7 @@ func (j *Jobs) RegisterOpts(job *Job, opts *RegisterOptions, q *WriteOptions) (*
 		}
 		req.PolicyOverride = opts.PolicyOverride
 		req.PreserveCounts = opts.PreserveCounts
+		req.PreserveResources = opts.PreserveResources
 		req.EvalPriority = opts.EvalPriority
 		req.Submission = opts.Submission
 	}
@@ -1486,10 +1488,11 @@ type JobRegisterRequest struct {
 	// If EnforceIndex is set then the job will only be registered if the passed
 	// JobModifyIndex matches the current Jobs index. If the index is zero, the
 	// register only occurs if the job is new.
-	EnforceIndex   bool   `json:",omitempty"`
-	JobModifyIndex uint64 `json:",omitempty"`
-	PolicyOverride bool   `json:",omitempty"`
-	PreserveCounts bool   `json:",omitempty"`
+	EnforceIndex      bool   `json:",omitempty"`
+	JobModifyIndex    uint64 `json:",omitempty"`
+	PolicyOverride    bool   `json:",omitempty"`
+	PreserveCounts    bool   `json:",omitempty"`
+	PreserveResources bool   `json:",omitempty"`
 
 	// EvalPriority is an optional priority to use on any evaluation created as
 	// a result on this job registration. This value must be between 1-100

api/jobs_test.go

@@ -186,6 +186,118 @@ func TestJobs_Register_NoPreserveCounts(t *testing.T) {
 	must.Eq(t, 3, status.TaskGroups["group3"].Desired) // new     => as specified
 }
 
+func TestJobs_Register_PreserveResources(t *testing.T) {
+	testutil.Parallel(t)
+
+	c, s := makeClient(t, nil, nil)
+	defer s.Stop()
+	jobs := c.Jobs()
+
+	// Listing jobs before registering returns nothing
+	resp, _, err := jobs.List(nil)
+	must.NoError(t, err)
+	must.SliceEmpty(t, resp)
+
+	// Create a job
+	task := NewTask("task", "exec").
+		SetConfig("command", "/bin/echo").
+		SetLogConfig(&LogConfig{
+			MaxFiles:      pointerOf(1),
+			MaxFileSizeMB: pointerOf(2),
+		})
+
+	group1 := NewTaskGroup("group1", 1).
+		AddTask(task).
+		RequireDisk(&EphemeralDisk{
+			SizeMB: pointerOf(25),
+		})
+
+	job := NewBatchJob("job", "redis", "global", 1).
+		AddDatacenter("dc1").
+		AddTaskGroup(group1)
+
+	// Create a job and register it
+	resp2, wm, err := jobs.Register(job, nil)
+	must.NoError(t, err)
+	must.NotNil(t, resp2)
+	must.UUIDv4(t, resp2.EvalID)
+	assertWriteMeta(t, wm)
+
+	// Update the job, new groups to test PreserveCounts
+	task.Resources = &Resources{
+		CPU:      pointerOf(50),
+		MemoryMB: pointerOf(128),
+	}
+
+	// Update the job, with PreserveResources = true
+	_, _, err = jobs.RegisterOpts(job, &RegisterOptions{
+		PreserveResources: true,
+	}, nil)
+	must.NoError(t, err)
+
+	// Query the job scale status
+	registered, _, err := jobs.Info(*job.ID, nil)
+	must.NoError(t, err)
+	must.Eq(t, 100, *registered.TaskGroups[0].Tasks[0].Resources.CPU)      // preserved
+	must.Eq(t, 300, *registered.TaskGroups[0].Tasks[0].Resources.MemoryMB) // preserved
+}
+
+func TestJobs_Register_NoPreserveResources(t *testing.T) {
+	testutil.Parallel(t)
+
+	c, s := makeClient(t, nil, nil)
+	defer s.Stop()
+	jobs := c.Jobs()
+
+	// Listing jobs before registering returns nothing
+	resp, _, err := jobs.List(nil)
+	must.NoError(t, err)
+	must.SliceEmpty(t, resp)
+
+	// Create a job
+	task := NewTask("task", "exec").
+		SetConfig("command", "/bin/echo").
+		SetLogConfig(&LogConfig{
+			MaxFiles:      pointerOf(1),
+			MaxFileSizeMB: pointerOf(2),
+		})
+
+	group1 := NewTaskGroup("group1", 1).
+		AddTask(task).
+		RequireDisk(&EphemeralDisk{
+			SizeMB: pointerOf(25),
+		})
+
+	job := NewBatchJob("job", "redis", "global", 1).
+		AddDatacenter("dc1").
+		AddTaskGroup(group1)
+
+	// Create a job and register it
+	resp2, wm, err := jobs.Register(job, nil)
+	must.NoError(t, err)
+	must.NotNil(t, resp2)
+	must.UUIDv4(t, resp2.EvalID)
+	assertWriteMeta(t, wm)
+
+	// Update the job, new groups to test PreserveCounts
+	task.Resources = &Resources{
+		CPU:      pointerOf(50),
+		MemoryMB: pointerOf(128),
+	}
+
+	// Update the job, with PreserveResources = true
+	_, _, err = jobs.RegisterOpts(job, &RegisterOptions{
+		PreserveResources: false,
+	}, nil)
+	must.NoError(t, err)
+
+	// Query the job scale status
+	registered, _, err := jobs.Info(*job.ID, nil)
+	must.NoError(t, err)
+	must.Eq(t, 50, *registered.TaskGroups[0].Tasks[0].Resources.CPU)       // updated
+	must.Eq(t, 128, *registered.TaskGroups[0].Tasks[0].Resources.MemoryMB) // updated
+}
+
 func TestJobs_Register_EvalPriority(t *testing.T) {
 	testutil.Parallel(t)