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alloc_runner.go
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alloc_runner.go
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package client
import (
"fmt"
"log"
"os"
"path/filepath"
"sync"
"time"
"github.com/hashicorp/go-multierror"
"github.com/hashicorp/nomad/client/allocdir"
"github.com/hashicorp/nomad/client/config"
"github.com/hashicorp/nomad/client/driver"
"github.com/hashicorp/nomad/nomad/structs"
)
const (
// taskReceivedSyncLimit is how long the client will wait before sending
// that a task was received to the server. The client does not immediately
// send that the task was received to the server because another transistion
// to running or failed is likely to occur immediately after and a single
// update will transfer all past state information. If not other transistion
// has occured up to this limit, we will send to the server.
taskReceivedSyncLimit = 30 * time.Second
)
// AllocStateUpdater is used to update the status of an allocation
type AllocStateUpdater func(alloc *structs.Allocation)
// AllocRunner is used to wrap an allocation and provide the execution context.
type AllocRunner struct {
config *config.Config
updater AllocStateUpdater
logger *log.Logger
consulService *ConsulService
alloc *structs.Allocation
allocClientStatus string // Explicit status of allocation. Set when there are failures
allocClientDescription string
allocLock sync.Mutex
dirtyCh chan struct{}
ctx *driver.ExecContext
ctxLock sync.Mutex
tasks map[string]*TaskRunner
taskStates map[string]*structs.TaskState
restored map[string]struct{}
taskLock sync.RWMutex
// taskReceivedTimer is used to mitigate updates sent to the server because
// we expect that shortly after receiving an alloc it will transistion
// state. We use a timer to send the update if this hasn't happened after a
// reasonable time.
taskReceivedTimer *time.Timer
taskStatusLock sync.RWMutex
updateCh chan *structs.Allocation
destroy bool
destroyCh chan struct{}
destroyLock sync.Mutex
waitCh chan struct{}
}
// allocRunnerState is used to snapshot the state of the alloc runner
type allocRunnerState struct {
Version string
Alloc *structs.Allocation
AllocClientStatus string
AllocClientDescription string
TaskStates map[string]*structs.TaskState
Context *driver.ExecContext
}
// NewAllocRunner is used to create a new allocation context
func NewAllocRunner(logger *log.Logger, config *config.Config, updater AllocStateUpdater,
alloc *structs.Allocation, consulService *ConsulService) *AllocRunner {
ar := &AllocRunner{
config: config,
updater: updater,
logger: logger,
alloc: alloc,
consulService: consulService,
dirtyCh: make(chan struct{}, 1),
tasks: make(map[string]*TaskRunner),
taskStates: copyTaskStates(alloc.TaskStates),
restored: make(map[string]struct{}),
updateCh: make(chan *structs.Allocation, 64),
destroyCh: make(chan struct{}),
waitCh: make(chan struct{}),
}
return ar
}
// stateFilePath returns the path to our state file
func (r *AllocRunner) stateFilePath() string {
r.allocLock.Lock()
defer r.allocLock.Unlock()
path := filepath.Join(r.config.StateDir, "alloc", r.alloc.ID, "state.json")
return path
}
// RestoreState is used to restore the state of the alloc runner
func (r *AllocRunner) RestoreState() error {
// Load the snapshot
var snap allocRunnerState
if err := restoreState(r.stateFilePath(), &snap); err != nil {
return err
}
// Restore fields
r.alloc = snap.Alloc
r.ctx = snap.Context
r.allocClientStatus = snap.AllocClientStatus
r.allocClientDescription = snap.AllocClientDescription
r.taskStates = snap.TaskStates
// Restore the task runners
var mErr multierror.Error
for name, state := range r.taskStates {
// Mark the task as restored.
r.restored[name] = struct{}{}
task := &structs.Task{Name: name}
tr := NewTaskRunner(r.logger, r.config, r.setTaskState, r.ctx, r.Alloc(),
task, r.consulService)
r.tasks[name] = tr
// Skip tasks in terminal states.
if state.State == structs.TaskStateDead {
continue
}
if err := tr.RestoreState(); err != nil {
r.logger.Printf("[ERR] client: failed to restore state for alloc %s task '%s': %v", r.alloc.ID, name, err)
mErr.Errors = append(mErr.Errors, err)
} else if !r.alloc.TerminalStatus() {
// Only start if the alloc isn't in a terminal status.
go tr.Run()
}
}
return mErr.ErrorOrNil()
}
// SaveState is used to snapshot the state of the alloc runner
// if the fullSync is marked as false only the state of the Alloc Runner
// is snapshotted. If fullSync is marked as true, we snapshot
// all the Task Runners associated with the Alloc
func (r *AllocRunner) SaveState() error {
if err := r.saveAllocRunnerState(); err != nil {
return err
}
// Save state for each task
r.taskLock.RLock()
defer r.taskLock.RUnlock()
var mErr multierror.Error
for _, tr := range r.tasks {
if err := r.saveTaskRunnerState(tr); err != nil {
mErr.Errors = append(mErr.Errors, err)
}
}
return mErr.ErrorOrNil()
}
func (r *AllocRunner) saveAllocRunnerState() error {
// Create the snapshot.
r.taskStatusLock.RLock()
states := copyTaskStates(r.taskStates)
r.taskStatusLock.RUnlock()
alloc := r.Alloc()
r.allocLock.Lock()
allocClientStatus := r.allocClientStatus
allocClientDescription := r.allocClientDescription
r.allocLock.Unlock()
r.ctxLock.Lock()
ctx := r.ctx
r.ctxLock.Unlock()
snap := allocRunnerState{
Version: r.config.Version,
Alloc: alloc,
Context: ctx,
AllocClientStatus: allocClientStatus,
AllocClientDescription: allocClientDescription,
TaskStates: states,
}
return persistState(r.stateFilePath(), &snap)
}
func (r *AllocRunner) saveTaskRunnerState(tr *TaskRunner) error {
var err error
if err = tr.SaveState(); err != nil {
r.logger.Printf("[ERR] client: failed to save state for alloc %s task '%s': %v",
r.alloc.ID, tr.task.Name, err)
}
return err
}
// DestroyState is used to cleanup after ourselves
func (r *AllocRunner) DestroyState() error {
return os.RemoveAll(filepath.Dir(r.stateFilePath()))
}
// DestroyContext is used to destroy the context
func (r *AllocRunner) DestroyContext() error {
return r.ctx.AllocDir.Destroy()
}
// copyTaskStates returns a copy of the passed task states.
func copyTaskStates(states map[string]*structs.TaskState) map[string]*structs.TaskState {
copy := make(map[string]*structs.TaskState, len(states))
for task, state := range states {
copy[task] = state.Copy()
}
return copy
}
// Alloc returns the associated allocation
func (r *AllocRunner) Alloc() *structs.Allocation {
r.allocLock.Lock()
alloc := r.alloc.Copy()
// The status has explicitely been set.
if r.allocClientStatus != "" || r.allocClientDescription != "" {
alloc.ClientStatus = r.allocClientStatus
alloc.ClientDescription = r.allocClientDescription
r.allocLock.Unlock()
return alloc
}
r.allocLock.Unlock()
// Scan the task states to determine the status of the alloc
var pending, running, dead, failed bool
r.taskStatusLock.RLock()
alloc.TaskStates = copyTaskStates(r.taskStates)
for _, state := range r.taskStates {
switch state.State {
case structs.TaskStateRunning:
running = true
case structs.TaskStatePending:
pending = true
case structs.TaskStateDead:
last := len(state.Events) - 1
if state.Events[last].Type == structs.TaskDriverFailure {
failed = true
} else {
dead = true
}
}
}
r.taskStatusLock.RUnlock()
// Determine the alloc status
if failed {
alloc.ClientStatus = structs.AllocClientStatusFailed
} else if running {
alloc.ClientStatus = structs.AllocClientStatusRunning
} else if pending {
alloc.ClientStatus = structs.AllocClientStatusPending
} else if dead {
alloc.ClientStatus = structs.AllocClientStatusDead
}
return alloc
}
// dirtySyncState is used to watch for state being marked dirty to sync
func (r *AllocRunner) dirtySyncState() {
for {
select {
case <-r.dirtyCh:
r.syncStatus()
case <-r.destroyCh:
return
}
}
}
// syncStatus is used to run and sync the status when it changes
func (r *AllocRunner) syncStatus() error {
// Get a copy of our alloc, update status server side and sync to disk
alloc := r.Alloc()
r.updater(alloc)
return r.saveAllocRunnerState()
}
// setStatus is used to update the allocation status
func (r *AllocRunner) setStatus(status, desc string) {
r.allocLock.Lock()
r.allocClientStatus = status
r.allocClientDescription = desc
r.allocLock.Unlock()
select {
case r.dirtyCh <- struct{}{}:
default:
}
}
// setTaskState is used to set the status of a task
func (r *AllocRunner) setTaskState(taskName, state string, event *structs.TaskEvent) {
r.taskStatusLock.Lock()
defer r.taskStatusLock.Unlock()
taskState, ok := r.taskStates[taskName]
if !ok {
r.logger.Printf("[ERR] client: setting task state for unknown task %q", taskName)
return
}
// Set the tasks state.
taskState.State = state
r.appendTaskEvent(taskState, event)
// We don't immediately mark ourselves as dirty, since in most cases there
// will immediately be another state transistion. This reduces traffic to
// the server.
if event != nil && event.Type == structs.TaskReceived {
if r.taskReceivedTimer == nil {
r.taskReceivedTimer = time.AfterFunc(taskReceivedSyncLimit, func() {
// Send a dirty signal to sync our state.
select {
case r.dirtyCh <- struct{}{}:
default:
}
})
}
return
}
// Cancel any existing received state timer.
if r.taskReceivedTimer != nil {
r.taskReceivedTimer.Stop()
}
select {
case r.dirtyCh <- struct{}{}:
default:
}
}
// appendTaskEvent updates the task status by appending the new event.
func (r *AllocRunner) appendTaskEvent(state *structs.TaskState, event *structs.TaskEvent) {
capacity := 10
if state.Events == nil {
state.Events = make([]*structs.TaskEvent, 0, capacity)
}
// If we hit capacity, then shift it.
if len(state.Events) == capacity {
old := state.Events
state.Events = make([]*structs.TaskEvent, 0, capacity)
state.Events = append(state.Events, old[1:]...)
}
state.Events = append(state.Events, event)
}
// Run is a long running goroutine used to manage an allocation
func (r *AllocRunner) Run() {
defer close(r.waitCh)
go r.dirtySyncState()
// Find the task group to run in the allocation
alloc := r.alloc
tg := alloc.Job.LookupTaskGroup(alloc.TaskGroup)
if tg == nil {
r.logger.Printf("[ERR] client: alloc '%s' for missing task group '%s'", alloc.ID, alloc.TaskGroup)
r.setStatus(structs.AllocClientStatusFailed, fmt.Sprintf("missing task group '%s'", alloc.TaskGroup))
return
}
// Create the execution context
r.ctxLock.Lock()
if r.ctx == nil {
allocDir := allocdir.NewAllocDir(filepath.Join(r.config.AllocDir, r.alloc.ID))
if err := allocDir.Build(tg.Tasks); err != nil {
r.logger.Printf("[WARN] client: failed to build task directories: %v", err)
r.setStatus(structs.AllocClientStatusFailed, fmt.Sprintf("failed to build task dirs for '%s'", alloc.TaskGroup))
r.ctxLock.Unlock()
return
}
r.ctx = driver.NewExecContext(allocDir, r.alloc.ID)
}
r.ctxLock.Unlock()
// Check if the allocation is in a terminal status. In this case, we don't
// start any of the task runners and directly wait for the destroy signal to
// clean up the allocation.
if alloc.TerminalStatus() {
r.logger.Printf("[DEBUG] client: alloc %q in terminal status, waiting for destroy", r.alloc.ID)
r.handleDestroy()
r.logger.Printf("[DEBUG] client: terminating runner for alloc '%s'", r.alloc.ID)
return
}
// Start the task runners
r.logger.Printf("[DEBUG] client: starting task runners for alloc '%s'", r.alloc.ID)
r.taskLock.Lock()
for _, task := range tg.Tasks {
if _, ok := r.restored[task.Name]; ok {
continue
}
tr := NewTaskRunner(r.logger, r.config, r.setTaskState, r.ctx, r.Alloc(),
task.Copy(), r.consulService)
r.tasks[task.Name] = tr
go tr.Run()
}
r.taskLock.Unlock()
OUTER:
// Wait for updates
for {
select {
case update := <-r.updateCh:
// Store the updated allocation.
r.allocLock.Lock()
r.alloc = update
r.allocLock.Unlock()
// Check if we're in a terminal status
if update.TerminalStatus() {
break OUTER
}
// Update the task groups
r.taskLock.RLock()
for _, task := range tg.Tasks {
tr := r.tasks[task.Name]
tr.Update(update)
}
r.taskLock.RUnlock()
case <-r.destroyCh:
break OUTER
}
}
// Destroy each sub-task
r.taskLock.Lock()
for _, tr := range r.tasks {
tr.Destroy()
}
// Wait for termination of the task runners
for _, tr := range r.tasks {
<-tr.WaitCh()
}
r.taskLock.Unlock()
// Final state sync
r.syncStatus()
// Block until we should destroy the state of the alloc
r.handleDestroy()
r.logger.Printf("[DEBUG] client: terminating runner for alloc '%s'", r.alloc.ID)
}
// handleDestroy blocks till the AllocRunner should be destroyed and does the
// necessary cleanup.
func (r *AllocRunner) handleDestroy() {
select {
case <-r.destroyCh:
if err := r.DestroyContext(); err != nil {
r.logger.Printf("[ERR] client: failed to destroy context for alloc '%s': %v",
r.alloc.ID, err)
}
if err := r.DestroyState(); err != nil {
r.logger.Printf("[ERR] client: failed to destroy state for alloc '%s': %v",
r.alloc.ID, err)
}
}
}
// Update is used to update the allocation of the context
func (r *AllocRunner) Update(update *structs.Allocation) {
select {
case r.updateCh <- update:
default:
r.logger.Printf("[ERR] client: dropping update to alloc '%s'", update.ID)
}
}
// shouldUpdate takes the AllocModifyIndex of an allocation sent from the server and
// checks if the current running allocation is behind and should be updated.
func (r *AllocRunner) shouldUpdate(serverIndex uint64) bool {
r.allocLock.Lock()
defer r.allocLock.Unlock()
return r.alloc.AllocModifyIndex < serverIndex
}
// Destroy is used to indicate that the allocation context should be destroyed
func (r *AllocRunner) Destroy() {
r.destroyLock.Lock()
defer r.destroyLock.Unlock()
if r.destroy {
return
}
r.destroy = true
close(r.destroyCh)
}
// WaitCh returns a channel to wait for termination
func (r *AllocRunner) WaitCh() <-chan struct{} {
return r.waitCh
}