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agent.go
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agent.go
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// Copyright 2014 The fleet Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package agent
import (
"encoding/json"
"fmt"
"time"
"github.com/coreos/fleet/job"
"github.com/coreos/fleet/log"
"github.com/coreos/fleet/machine"
"github.com/coreos/fleet/pkg"
"github.com/coreos/fleet/registry"
"github.com/coreos/fleet/unit"
)
const (
// TTL to use with all state pushed to Registry
DefaultTTL = "30s"
)
type Agent struct {
registry registry.Registry
um unit.UnitManager
uGen *unit.UnitStateGenerator
Machine machine.Machine
ttl time.Duration
cache *agentCache
}
func New(mgr unit.UnitManager, uGen *unit.UnitStateGenerator, reg registry.Registry, mach machine.Machine, ttl time.Duration) *Agent {
return &Agent{reg, mgr, uGen, mach, ttl, &agentCache{}}
}
func (a *Agent) MarshalJSON() ([]byte, error) {
data := struct {
Cache *agentCache
}{
Cache: a.cache,
}
return json.Marshal(data)
}
// Heartbeat updates the Registry periodically with an acknowledgement of the
// Jobs this Agent is expected to be running.
func (a *Agent) Heartbeat(stop <-chan struct{}) {
a.heartbeatJobs(a.ttl, stop)
}
func (a *Agent) heartbeatJobs(ttl time.Duration, stop <-chan struct{}) {
heartbeat := func() {
machID := a.Machine.State().ID
launched := a.cache.launchedJobs()
for _, j := range launched {
go a.registry.UnitHeartbeat(j, machID, ttl)
}
}
var interval time.Duration
if ttl > 10*time.Second {
interval = ttl * 4 / 5
} else {
interval = ttl / 2
}
ticker := time.Tick(interval)
for {
select {
case <-stop:
log.Debug("HeartbeatJobs exiting due to stop signal")
return
case <-ticker:
log.Debug("HeartbeatJobs tick")
heartbeat()
}
}
}
func (a *Agent) reloadUnitFiles() error {
return a.um.ReloadUnitFiles()
}
func (a *Agent) loadUnit(u *job.Unit) error {
a.cache.setTargetState(u.Name, job.JobStateLoaded)
a.uGen.Subscribe(u.Name)
return a.um.Load(u.Name, u.Unit)
}
func (a *Agent) unloadUnit(unitName string) error {
a.registry.ClearUnitHeartbeat(unitName)
a.cache.dropTargetState(unitName)
errStop := a.um.TriggerStop(unitName)
if errStop != nil {
log.Warningf("TriggerStop on systemd unit %s returned: %v", unitName, errStop)
} else {
log.Infof("Stopped unit(%s)", unitName)
}
a.uGen.Unsubscribe(unitName)
// unit should be unloaded and unit file should be removed, only if the unit
// could be successfully stopped. Otherwise the unit could get into a state
// where the unit cannot be stopped via fleet, because the unit file was
// already removed. See also https://github.com/coreos/fleet/issues/1216.
var errUnload error
if errStop == nil {
errUnload = a.um.Unload(unitName)
}
return errUnload
}
func (a *Agent) startUnit(unitName string) error {
a.cache.setTargetState(unitName, job.JobStateLaunched)
machID := a.Machine.State().ID
a.registry.UnitHeartbeat(unitName, machID, a.ttl)
return a.um.TriggerStart(unitName)
}
func (a *Agent) stopUnit(unitName string) error {
a.cache.setTargetState(unitName, job.JobStateLoaded)
a.registry.ClearUnitHeartbeat(unitName)
return a.um.TriggerStop(unitName)
}
type unitState struct {
state job.JobState
hash string
}
type unitStates map[string]unitState
// units returns a map representing the current state of units known by the agent.
func (a *Agent) units() (unitStates, error) {
launched := pkg.NewUnsafeSet()
for _, jName := range a.cache.launchedJobs() {
launched.Add(jName)
}
loaded := pkg.NewUnsafeSet()
for _, jName := range a.cache.loadedJobs() {
loaded.Add(jName)
}
units, err := a.um.Units()
if err != nil {
return nil, fmt.Errorf("failed fetching loaded units from UnitManager: %v", err)
}
filter := pkg.NewUnsafeSet()
for _, u := range units {
filter.Add(u)
}
uStates, err := a.um.GetUnitStates(filter)
if err != nil {
return nil, fmt.Errorf("failed fetching unit states from UnitManager: %v", err)
}
states := make(unitStates)
for uName, uState := range uStates {
js := job.JobStateInactive
if loaded.Contains(uName) {
js = job.JobStateLoaded
} else if launched.Contains(uName) {
js = job.JobStateLaunched
}
us := unitState{
state: js,
hash: uState.UnitHash,
}
states[uName] = us
}
return states, nil
}