436 lines
14 KiB
Go
436 lines
14 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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package drainer
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import (
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"context"
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"sync"
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"time"
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log "github.com/hashicorp/go-hclog"
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"github.com/hashicorp/nomad/helper/pointer"
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"github.com/hashicorp/nomad/helper/uuid"
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"github.com/hashicorp/nomad/nomad/state"
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"github.com/hashicorp/nomad/nomad/structs"
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"golang.org/x/time/rate"
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)
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var (
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// stateReadErrorDelay is the delay to apply before retrying reading state
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// when there is an error
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stateReadErrorDelay = 1 * time.Second
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)
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const (
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// LimitStateQueriesPerSecond is the number of state queries allowed per
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// second
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LimitStateQueriesPerSecond = 100.0
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// BatchUpdateInterval is how long we wait to batch updates
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BatchUpdateInterval = 1 * time.Second
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// NodeDeadlineCoalesceWindow is the duration in which deadlining nodes will
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// be coalesced together
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NodeDeadlineCoalesceWindow = 5 * time.Second
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// NodeDrainEventComplete is used to indicate that the node drain is
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// finished.
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NodeDrainEventComplete = "Node drain complete"
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// NodeDrainEventDetailDeadlined is the key to use when the drain is
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// complete because a deadline. The acceptable values are "true" and "false"
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NodeDrainEventDetailDeadlined = "deadline_reached"
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)
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// RaftApplier contains methods for applying the raft requests required by the
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// NodeDrainer.
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type RaftApplier interface {
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AllocUpdateDesiredTransition(allocs map[string]*structs.DesiredTransition, evals []*structs.Evaluation) (uint64, error)
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NodesDrainComplete(nodes []string, event *structs.NodeEvent) (uint64, error)
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}
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// NodeTracker is the interface to notify an object that is tracking draining
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// nodes of changes
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type NodeTracker interface {
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// TrackedNodes returns all the nodes that are currently tracked as
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// draining.
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TrackedNodes() map[string]*structs.Node
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// Remove removes a node from the draining set.
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Remove(nodeID string)
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// Update either updates the specification of a draining node or tracks the
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// node as draining.
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Update(node *structs.Node)
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}
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// DrainingJobWatcherFactory returns a new DrainingJobWatcher
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type DrainingJobWatcherFactory func(context.Context, *rate.Limiter, *state.StateStore, log.Logger) DrainingJobWatcher
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// DrainingNodeWatcherFactory returns a new DrainingNodeWatcher
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type DrainingNodeWatcherFactory func(context.Context, *rate.Limiter, *state.StateStore, log.Logger, NodeTracker) DrainingNodeWatcher
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// DrainDeadlineNotifierFactory returns a new DrainDeadlineNotifier
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type DrainDeadlineNotifierFactory func(context.Context) DrainDeadlineNotifier
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// GetDrainingJobWatcher returns a draining job watcher
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func GetDrainingJobWatcher(ctx context.Context, limiter *rate.Limiter, state *state.StateStore, logger log.Logger) DrainingJobWatcher {
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return NewDrainingJobWatcher(ctx, limiter, state, logger)
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}
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// GetDeadlineNotifier returns a node deadline notifier with default coalescing.
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func GetDeadlineNotifier(ctx context.Context) DrainDeadlineNotifier {
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return NewDeadlineHeap(ctx, NodeDeadlineCoalesceWindow)
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}
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// GetNodeWatcherFactory returns a DrainingNodeWatcherFactory
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func GetNodeWatcherFactory() DrainingNodeWatcherFactory {
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return func(ctx context.Context, limiter *rate.Limiter, state *state.StateStore, logger log.Logger, tracker NodeTracker) DrainingNodeWatcher {
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return NewNodeDrainWatcher(ctx, limiter, state, logger, tracker)
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}
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}
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// allocMigrateBatcher is used to batch allocation updates.
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type allocMigrateBatcher struct {
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// updates holds pending client status updates for allocations
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updates []*structs.Allocation
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// updateFuture is used to wait for the pending batch update
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// to complete. This may be nil if no batch is pending.
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updateFuture *structs.BatchFuture
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// updateTimer is the timer that will trigger the next batch
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// update, and may be nil if there is no batch pending.
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updateTimer *time.Timer
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batchWindow time.Duration
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// synchronizes access to the updates list, the future and the timer.
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sync.Mutex
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}
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// NodeDrainerConfig is used to configure a new node drainer.
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type NodeDrainerConfig struct {
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Logger log.Logger
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Raft RaftApplier
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JobFactory DrainingJobWatcherFactory
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NodeFactory DrainingNodeWatcherFactory
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DrainDeadlineFactory DrainDeadlineNotifierFactory
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// StateQueriesPerSecond configures the query limit against the state store
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// that is allowed by the node drainer.
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StateQueriesPerSecond float64
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// BatchUpdateInterval is the interval in which allocation updates are
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// batched.
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BatchUpdateInterval time.Duration
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}
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// NodeDrainer is used to orchestrate migrating allocations off of draining
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// nodes.
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type NodeDrainer struct {
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enabled bool
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logger log.Logger
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// nodes is the set of draining nodes
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nodes map[string]*drainingNode
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// nodeWatcher watches for nodes to transition in and out of drain state.
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nodeWatcher DrainingNodeWatcher
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nodeFactory DrainingNodeWatcherFactory
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// jobWatcher watches draining jobs and emits desired drains and notifies
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// when migrations take place.
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jobWatcher DrainingJobWatcher
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jobFactory DrainingJobWatcherFactory
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// deadlineNotifier notifies when nodes reach their drain deadline.
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deadlineNotifier DrainDeadlineNotifier
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deadlineNotifierFactory DrainDeadlineNotifierFactory
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// state is the state that is watched for state changes.
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state *state.StateStore
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// queryLimiter is used to limit the rate of blocking queries
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queryLimiter *rate.Limiter
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// raft is a shim around the raft messages necessary for draining
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raft RaftApplier
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// batcher is used to batch alloc migrations.
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batcher allocMigrateBatcher
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// ctx and exitFn are used to cancel the watcher
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ctx context.Context
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exitFn context.CancelFunc
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l sync.RWMutex
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}
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// NewNodeDrainer returns a new new node drainer. The node drainer is
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// responsible for marking allocations on draining nodes with a desired
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// migration transition, updating the drain strategy on nodes when they are
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// complete and creating evaluations for the system to react to these changes.
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func NewNodeDrainer(c *NodeDrainerConfig) *NodeDrainer {
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return &NodeDrainer{
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raft: c.Raft,
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logger: c.Logger.Named("drain"),
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jobFactory: c.JobFactory,
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nodeFactory: c.NodeFactory,
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deadlineNotifierFactory: c.DrainDeadlineFactory,
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queryLimiter: rate.NewLimiter(rate.Limit(c.StateQueriesPerSecond), 100),
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batcher: allocMigrateBatcher{
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batchWindow: c.BatchUpdateInterval,
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},
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}
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}
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// SetEnabled will start or stop the node draining goroutine depending on the
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// enabled boolean.
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func (n *NodeDrainer) SetEnabled(enabled bool, state *state.StateStore) {
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n.l.Lock()
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defer n.l.Unlock()
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// If we are starting now or have a new state, init state and start the
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// run loop
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n.enabled = enabled
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if enabled {
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n.flush(state)
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go n.run(n.ctx)
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} else if !enabled && n.exitFn != nil {
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n.exitFn()
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}
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}
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// flush is used to clear the state of the watcher
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func (n *NodeDrainer) flush(state *state.StateStore) {
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// Cancel anything that may be running.
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if n.exitFn != nil {
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n.exitFn()
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}
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// Store the new state
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if state != nil {
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n.state = state
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}
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n.ctx, n.exitFn = context.WithCancel(context.Background())
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n.jobWatcher = n.jobFactory(n.ctx, n.queryLimiter, n.state, n.logger)
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n.nodeWatcher = n.nodeFactory(n.ctx, n.queryLimiter, n.state, n.logger, n)
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n.deadlineNotifier = n.deadlineNotifierFactory(n.ctx)
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n.nodes = make(map[string]*drainingNode, 32)
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}
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// run is a long lived event handler that receives changes from the relevant
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// watchers and takes action based on them.
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func (n *NodeDrainer) run(ctx context.Context) {
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for {
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select {
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case <-n.ctx.Done():
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return
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case nodes := <-n.deadlineNotifier.NextBatch():
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n.handleDeadlinedNodes(nodes)
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case req := <-n.jobWatcher.Drain():
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n.handleJobAllocDrain(req)
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case allocs := <-n.jobWatcher.Migrated():
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n.handleMigratedAllocs(allocs)
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}
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}
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}
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// handleDeadlinedNodes handles a set of nodes reaching their drain deadline.
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// The handler detects the remaining allocations on the nodes and immediately
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// marks them for migration.
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func (n *NodeDrainer) handleDeadlinedNodes(nodes []string) {
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// Retrieve the set of allocations that will be force stopped.
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var forceStop []*structs.Allocation
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n.l.RLock()
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for _, node := range nodes {
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draining, ok := n.nodes[node]
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if !ok {
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n.logger.Debug("skipping untracked deadlined node", "node_id", node)
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continue
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}
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allocs, err := draining.RemainingAllocs()
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if err != nil {
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n.logger.Error("failed to retrieve allocs on deadlined node", "node_id", node, "error", err)
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continue
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}
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n.logger.Debug("node deadlined causing allocs to be force stopped", "node_id", node, "num_allocs", len(allocs))
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forceStop = append(forceStop, allocs...)
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}
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n.l.RUnlock()
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n.batchDrainAllocs(forceStop)
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// Create the node event
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event := structs.NewNodeEvent().
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SetSubsystem(structs.NodeEventSubsystemDrain).
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SetMessage(NodeDrainEventComplete).
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AddDetail(NodeDrainEventDetailDeadlined, "true")
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// Submit the node transitions in a sharded form to ensure a reasonable
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// Raft transaction size.
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for _, nodes := range partitionIds(defaultMaxIdsPerTxn, nodes) {
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if _, err := n.raft.NodesDrainComplete(nodes, event); err != nil {
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n.logger.Error("failed to unset drain for nodes", "error", err)
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}
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}
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}
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// handleJobAllocDrain handles marking a set of allocations as having a desired
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// transition to drain. The handler blocks till the changes to the allocation
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// have occurred.
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func (n *NodeDrainer) handleJobAllocDrain(req *DrainRequest) {
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index, err := n.batchDrainAllocs(req.Allocs)
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req.Resp.Respond(index, err)
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}
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// handleMigratedAllocs checks to see if any nodes can be considered done
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// draining based on the set of allocations that have migrated because of an
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// ongoing drain for a job.
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func (n *NodeDrainer) handleMigratedAllocs(allocs []*structs.Allocation) {
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// Determine the set of nodes that were effected
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nodes := make(map[string]struct{})
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for _, alloc := range allocs {
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nodes[alloc.NodeID] = struct{}{}
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}
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var done []string
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var remainingAllocs []*structs.Allocation
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// For each node, check if it is now done
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n.l.RLock()
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for node := range nodes {
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draining, ok := n.nodes[node]
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if !ok {
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continue
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}
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isDone, err := draining.IsDone()
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if err != nil {
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n.logger.Error("error checking if node is done draining", "node_id", node, "error", err)
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continue
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}
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if !isDone {
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continue
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}
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done = append(done, node)
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remaining, err := draining.RemainingAllocs()
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if err != nil {
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n.logger.Error("node is done draining but encountered an error getting remaining allocs", "node_id", node, "error", err)
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continue
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}
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remainingAllocs = append(remainingAllocs, remaining...)
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}
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n.l.RUnlock()
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// Stop any running system jobs on otherwise done nodes
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if len(remainingAllocs) > 0 {
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future := structs.NewBatchFuture()
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n.drainAllocs(future, remainingAllocs)
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if err := future.Wait(); err != nil {
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n.logger.Error("failed to drain remaining allocs from done nodes", "num_allocs", len(remainingAllocs), "error", err)
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}
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}
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// Create the node event
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event := structs.NewNodeEvent().
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SetSubsystem(structs.NodeEventSubsystemDrain).
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SetMessage(NodeDrainEventComplete)
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// Submit the node transitions in a sharded form to ensure a reasonable
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// Raft transaction size.
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for _, nodes := range partitionIds(defaultMaxIdsPerTxn, done) {
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if _, err := n.raft.NodesDrainComplete(nodes, event); err != nil {
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n.logger.Error("failed to unset drain for nodes", "error", err)
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}
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}
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}
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// batchDrainAllocs is used to batch the draining of allocations. It will block
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// until the batch is complete.
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func (n *NodeDrainer) batchDrainAllocs(allocs []*structs.Allocation) (uint64, error) {
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// Add this to the batch
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n.batcher.Lock()
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n.batcher.updates = append(n.batcher.updates, allocs...)
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// Start a new batch if none
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future := n.batcher.updateFuture
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if future == nil {
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future = structs.NewBatchFuture()
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n.batcher.updateFuture = future
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n.batcher.updateTimer = time.AfterFunc(n.batcher.batchWindow, func() {
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// Get the pending updates
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n.batcher.Lock()
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updates := n.batcher.updates
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future := n.batcher.updateFuture
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n.batcher.updates = nil
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n.batcher.updateFuture = nil
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n.batcher.updateTimer = nil
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n.batcher.Unlock()
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// Perform the batch update
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n.drainAllocs(future, updates)
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})
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}
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n.batcher.Unlock()
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if err := future.Wait(); err != nil {
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return 0, err
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}
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return future.Index(), nil
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}
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// drainAllocs is a non batch, marking of the desired transition to migrate for
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// the set of allocations. It will also create the necessary evaluations for the
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// affected jobs.
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func (n *NodeDrainer) drainAllocs(future *structs.BatchFuture, allocs []*structs.Allocation) {
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// Compute the effected jobs and make the transition map
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jobs := make(map[structs.NamespacedID]*structs.Allocation, 4)
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transitions := make(map[string]*structs.DesiredTransition, len(allocs))
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for _, alloc := range allocs {
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transitions[alloc.ID] = &structs.DesiredTransition{
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Migrate: pointer.Of(true),
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}
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jobs[alloc.JobNamespacedID()] = alloc
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}
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evals := make([]*structs.Evaluation, 0, len(jobs))
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now := time.Now().UTC().UnixNano()
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for _, alloc := range jobs {
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evals = append(evals, &structs.Evaluation{
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ID: uuid.Generate(),
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Namespace: alloc.Namespace,
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Priority: alloc.Job.Priority,
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Type: alloc.Job.Type,
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TriggeredBy: structs.EvalTriggerNodeDrain,
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JobID: alloc.JobID,
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Status: structs.EvalStatusPending,
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CreateTime: now,
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ModifyTime: now,
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})
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}
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// Commit this update via Raft
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var finalIndex uint64
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for _, u := range partitionAllocDrain(defaultMaxIdsPerTxn, transitions, evals) {
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index, err := n.raft.AllocUpdateDesiredTransition(u.Transitions, u.Evals)
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if err != nil {
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future.Respond(0, err)
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return
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}
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finalIndex = index
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}
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future.Respond(finalIndex, nil)
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}
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