Add System Scheduler that runs tasks on every node

nomad/mock/mock.go

@@ -109,6 +109,59 @@ func Job() *structs.Job {
 	return job
 }
 
+func SystemJob() *structs.Job {
+	job := &structs.Job{
+		Region:      "global",
+		ID:          structs.GenerateUUID(),
+		Name:        "my-job",
+		Type:        structs.JobTypeSystem,
+		Priority:    100,
+		AllAtOnce:   false,
+		Datacenters: []string{"dc1"},
+		Constraints: []*structs.Constraint{
+			&structs.Constraint{
+				Hard:    true,
+				LTarget: "$attr.kernel.name",
+				RTarget: "linux",
+				Operand: "=",
+			},
+		},
+		TaskGroups: []*structs.TaskGroup{
+			&structs.TaskGroup{
+				Name:  "web",
+				Count: 1,
+				Tasks: []*structs.Task{
+					&structs.Task{
+						Name:   "web",
+						Driver: "exec",
+						Config: map[string]string{
+							"command": "/bin/date",
+							"args":    "+%s",
+						},
+						Resources: &structs.Resources{
+							CPU:      500,
+							MemoryMB: 256,
+							Networks: []*structs.NetworkResource{
+								&structs.NetworkResource{
+									MBits:        50,
+									DynamicPorts: []string{"http"},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		Meta: map[string]string{
+			"owner": "armon",
+		},
+		Status:      structs.JobStatusPending,
+		CreateIndex: 42,
+		ModifyIndex: 99,
+	}
+	return job
+}
+
 func Eval() *structs.Evaluation {
 	eval := &structs.Evaluation{
 		ID:       structs.GenerateUUID(),

nomad/structs/structs.go

@@ -699,6 +699,7 @@ const (
 	JobTypeCore    = "_core"
 	JobTypeService = "service"
 	JobTypeBatch   = "batch"
+	JobTypeSystem  = "system"
 )
 
 const (
@@ -828,6 +829,12 @@ func (j *Job) Validate() error {
 		} else {
 			taskGroups[tg.Name] = idx
 		}
+
+		if j.Type == "system" && tg.Count != 1 {
+			mErr.Errors = append(mErr.Errors,
+				fmt.Errorf("Job task group %d has count %d. Only count of 1 is supported with system scheduler",
+					idx+1, tg.Count))
+		}
 	}
 
 	// Validate the task group

scheduler/feasible.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"reflect"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/hashicorp/go-version"
@@ -129,10 +130,22 @@ func (iter *DriverIterator) Reset() {
 func (iter *DriverIterator) hasDrivers(option *structs.Node) bool {
 	for driver := range iter.drivers {
 		driverStr := fmt.Sprintf("driver.%s", driver)
-		_, ok := option.Attributes[driverStr]
+		value, ok := option.Attributes[driverStr]
 		if !ok {
 			return false
 		}
+
+		enabled, err := strconv.ParseBool(value)
+		if err != nil {
+			iter.ctx.Logger().
+				Printf("[WARN] scheduler.DriverIterator: node %v has invalid driver setting %v: %v",
+				option.ID, driverStr, value)
+			return false
+		}
+
+		if !enabled {
+			return false
+		}
 	}
 	return true
 }

scheduler/feasible_test.go

@@ -82,11 +82,14 @@ func TestDriverIterator(t *testing.T) {
 		mock.Node(),
 		mock.Node(),
 		mock.Node(),
+		mock.Node(),
 	}
 	static := NewStaticIterator(ctx, nodes)
 
-	nodes[0].Attributes["driver.foo"] = "2"
-	nodes[2].Attributes["driver.foo"] = "2"
+	nodes[0].Attributes["driver.foo"] = "1"
+	nodes[1].Attributes["driver.foo"] = "0"
+	nodes[2].Attributes["driver.foo"] = "true"
+	nodes[3].Attributes["driver.foo"] = "False"
 
 	drivers := map[string]struct{}{
 		"exec": struct{}{},

scheduler/generic_sched.go

@@ -82,18 +82,6 @@ func NewBatchScheduler(logger *log.Logger, state State, planner Planner) Schedul
 	return s
 }
 
-// setStatus is used to update the status of the evaluation
-func (s *GenericScheduler) setStatus(status, desc string) error {
-	s.logger.Printf("[DEBUG] sched: %#v: setting status to %s", s.eval, status)
-	newEval := s.eval.Copy()
-	newEval.Status = status
-	newEval.StatusDescription = desc
-	if s.nextEval != nil {
-		newEval.NextEval = s.nextEval.ID
-	}
-	return s.planner.UpdateEval(newEval)
-}
-
 // Process is used to handle a single evaluation
 func (s *GenericScheduler) Process(eval *structs.Evaluation) error {
 	// Store the evaluation
@@ -106,7 +94,7 @@ func (s *GenericScheduler) Process(eval *structs.Evaluation) error {
 	default:
 		desc := fmt.Sprintf("scheduler cannot handle '%s' evaluation reason",
 			eval.TriggeredBy)
-		return s.setStatus(structs.EvalStatusFailed, desc)
+		return setStatus(s.logger, s.planner, s.eval, s.nextEval, structs.EvalStatusFailed, desc)
 	}
 
 	// Retry up to the maxScheduleAttempts
@@ -116,13 +104,13 @@ func (s *GenericScheduler) Process(eval *structs.Evaluation) error {
 	}
 	if err := retryMax(limit, s.process); err != nil {
 		if statusErr, ok := err.(*SetStatusError); ok {
-			return s.setStatus(statusErr.EvalStatus, err.Error())
+			return setStatus(s.logger, s.planner, s.eval, s.nextEval, statusErr.EvalStatus, err.Error())
 		}
 		return err
 	}
 
 	// Update the status to complete
-	return s.setStatus(structs.EvalStatusComplete, "")
+	return setStatus(s.logger, s.planner, s.eval, s.nextEval, structs.EvalStatusComplete, "")
 }
 
 // process is wrapped in retryMax to iteratively run the handler until we have no
@@ -143,7 +131,7 @@ func (s *GenericScheduler) process() (bool, error) {
 	s.ctx = NewEvalContext(s.state, s.plan, s.logger)
 
 	// Construct the placement stack
-	s.stack = NewGenericStack(s.batch, s.ctx, nil)
+	s.stack = NewGenericStack(s.batch, s.ctx)
 	if s.job != nil {
 		s.stack.SetJob(s.job)
 	}
@@ -231,7 +219,7 @@ func (s *GenericScheduler) computeJobAllocs() error {
 	}
 
 	// Attempt to do the upgrades in place
-	diff.update = s.inplaceUpdate(diff.update)
+	diff.update = inplaceUpdate(s.ctx, s.eval, s.job, s.stack, diff.update)
 
 	// Check if a rolling upgrade strategy is being used
 	limit := len(diff.update) + len(diff.migrate)
@@ -240,10 +228,10 @@ func (s *GenericScheduler) computeJobAllocs() error {
 	}
 
 	// Treat migrations as an eviction and a new placement.
-	s.evictAndPlace(diff, diff.migrate, allocMigrating, &limit)
+	s.limitReached = evictAndPlace(s.ctx, diff, diff.migrate, allocMigrating, &limit)
 
 	// Treat non in-place updates as an eviction and new placement.
-	s.evictAndPlace(diff, diff.update, allocUpdating, &limit)
+	s.limitReached = evictAndPlace(s.ctx, diff, diff.update, allocUpdating, &limit)
 
 	// Nothing remaining to do if placement is not required
 	if len(diff.place) == 0 {
@@ -254,101 +242,6 @@ func (s *GenericScheduler) computeJobAllocs() error {
 	return s.computePlacements(diff.place)
 }
 
-// evictAndPlace is used to mark allocations for evicts and add them to the placement queue
-func (s *GenericScheduler) evictAndPlace(diff *diffResult, allocs []allocTuple, desc string, limit *int) {
-	n := len(allocs)
-	for i := 0; i < n && i < *limit; i++ {
-		a := allocs[i]
-		s.plan.AppendUpdate(a.Alloc, structs.AllocDesiredStatusStop, desc)
-		diff.place = append(diff.place, a)
-	}
-	if n <= *limit {
-		*limit -= n
-	} else {
-		*limit = 0
-		s.limitReached = true
-	}
-}
-
-// inplaceUpdate attempts to update allocations in-place where possible.
-func (s *GenericScheduler) inplaceUpdate(updates []allocTuple) []allocTuple {
-	n := len(updates)
-	inplace := 0
-	for i := 0; i < n; i++ {
-		// Get the udpate
-		update := updates[i]
-
-		// Check if the task drivers or config has changed, requires
-		// a rolling upgrade since that cannot be done in-place.
-		existing := update.Alloc.Job.LookupTaskGroup(update.TaskGroup.Name)
-		if tasksUpdated(update.TaskGroup, existing) {
-			continue
-		}
-
-		// Get the existing node
-		node, err := s.state.NodeByID(update.Alloc.NodeID)
-		if err != nil {
-			s.logger.Printf("[ERR] sched: %#v failed to get node '%s': %v",
-				s.eval, update.Alloc.NodeID, err)
-			continue
-		}
-		if node == nil {
-			continue
-		}
-
-		// Set the existing node as the base set
-		s.stack.SetNodes([]*structs.Node{node})
-
-		// Stage an eviction of the current allocation
-		s.plan.AppendUpdate(update.Alloc, structs.AllocDesiredStatusStop,
-			allocInPlace)
-
-		// Attempt to match the task group
-		option, size := s.stack.Select(update.TaskGroup)
-
-		// Pop the allocation
-		s.plan.PopUpdate(update.Alloc)
-
-		// Skip if we could not do an in-place update
-		if option == nil {
-			continue
-		}
-
-		// Restore the network offers from the existing allocation.
-		// We do not allow network resources (reserved/dynamic ports)
-		// to be updated. This is guarded in taskUpdated, so we can
-		// safely restore those here.
-		for task, resources := range option.TaskResources {
-			existing := update.Alloc.TaskResources[task]
-			resources.Networks = existing.Networks
-		}
-
-		// Create a shallow copy
-		newAlloc := new(structs.Allocation)
-		*newAlloc = *update.Alloc
-
-		// Update the allocation
-		newAlloc.EvalID = s.eval.ID
-		newAlloc.Job = s.job
-		newAlloc.Resources = size
-		newAlloc.TaskResources = option.TaskResources
-		newAlloc.Metrics = s.ctx.Metrics()
-		newAlloc.DesiredStatus = structs.AllocDesiredStatusRun
-		newAlloc.ClientStatus = structs.AllocClientStatusPending
-		s.plan.AppendAlloc(newAlloc)
-
-		// Remove this allocation from the slice
-		updates[i] = updates[n-1]
-		i--
-		n--
-		inplace++
-	}
-	if len(updates) > 0 {
-		s.logger.Printf("[DEBUG] sched: %#v: %d in-place updates of %d", s.eval, inplace, len(updates))
-	}
-	return updates[:n]
-}
-
 // computePlacements computes placements for allocations
 func (s *GenericScheduler) computePlacements(place []allocTuple) error {
 	// Get the base nodes

scheduler/generic_sched_test.go

@@ -22,7 +22,7 @@ func TestServiceSched_JobRegister(t *testing.T) {
 	job := mock.Job()
 	noErr(t, h.State.UpsertJob(h.NextIndex(), job))
 
-	// Create a mock evaluation to deregister the job
+	// Create a mock evaluation to register the job
 	eval := &structs.Evaluation{
 		ID:          structs.GenerateUUID(),
 		Priority:    job.Priority,
@@ -71,7 +71,7 @@ func TestServiceSched_JobRegister_AllocFail(t *testing.T) {
 	job := mock.Job()
 	noErr(t, h.State.UpsertJob(h.NextIndex(), job))
 
-	// Create a mock evaluation to deregister the job
+	// Create a mock evaluation to register the job
 	eval := &structs.Evaluation{
 		ID:          structs.GenerateUUID(),
 		Priority:    job.Priority,
@@ -550,7 +550,7 @@ func TestServiceSched_RetryLimit(t *testing.T) {
 	job := mock.Job()
 	noErr(t, h.State.UpsertJob(h.NextIndex(), job))
 
-	// Create a mock evaluation to deregister the job
+	// Create a mock evaluation to register the job
 	eval := &structs.Evaluation{
 		ID:          structs.GenerateUUID(),
 		Priority:    job.Priority,

scheduler/scheduler.go

@@ -13,6 +13,7 @@ import (
 var BuiltinSchedulers = map[string]Factory{
 	"service": NewServiceScheduler,
 	"batch":   NewBatchScheduler,
+	"system":  NewSystemScheduler,
 }
 
 // NewScheduler is used to instantiate and return a new scheduler