fleetctl: Adding restart command

Documentation/using-the-client.md

@@ -75,11 +75,16 @@ Start and stop units with the `start` and `stop` commands:
 $ fleetctl start goodbye.service
 Unit goodbye.service launched on 85c0c595.../172.17.8.102
 
+$ fleetctl restart goodbye.service
+Unit goodbye.service loaded on 85c0c595.../172.17.8.102
+Unit goodbye.service launched on 85c0c595.../172.17.8.102
+
 $ fleetctl stop goodbye.service
 Unit goodbye.service loaded on 85c0c595.../172.17.8.102
 ```
 
 If the unit does not exist when calling `start`, fleetctl will first search for a local unit file, submit it and schedule it.
+If the unit is stopped when calling `restart`, fleetctl will start it.
 
 ### Scheduling units
 

fleetctl/fleetctl.go

@@ -166,6 +166,7 @@ func init() {
 		cmdSSH,
 		cmdStartUnit,
 		cmdStatusUnits,
+		cmdRestartUnit,
 		cmdStopUnit,
 		cmdSubmitUnit,
 		cmdUnloadUnit,

fleetctl/restart.go

@@ -0,0 +1,104 @@
+/*
+   Copyright 2014 CoreOS, Inc.
+
+   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 main
+
+import (
+	"os"
+
+	"github.com/coreos/fleet/job"
+	"github.com/coreos/fleet/log"
+	"github.com/coreos/fleet/schema"
+)
+
+var cmdRestartUnit = &Command{
+	Name:    "restart",
+	Summary: "Instruct systemd to rolling restart one or more units in the cluster.",
+	Usage:   "[--block-attempts=N] UNIT...",
+	Description: `Restarts one or more units in the cluster. If they are stopped it starts them.
+
+Instructs systemd on the host machine to stop then start the unit, deferring to systemd
+completely for any custom restart directives (i.e. ExecStop options in the unit
+file).
+
+For units which are not global, restart operations are performed synchronously,
+which means fleetctl will block until it detects that the unit(s) have
+transitioned to a stopped state and then back to a started state. This behaviour can be configured with the
+respective --block-attempts options. Restart operations on global
+units are always non-blocking.
+
+Restart a single unit:
+	fleetctl restart foo.service
+
+Restart an entire directory of units with glob matching, without waiting:
+	fleetctl restart myservice/*`,
+	Run: runRestartUnit,
+}
+
+func init() {
+	cmdRestartUnit.Flags.IntVar(&sharedFlags.BlockAttempts, "block-attempts", 0, "Wait until the units are stopped/started, performing up to N attempts before giving up. A value of 0 indicates no limit. Does not apply to global units.")
+}
+
+func runRestartUnit(args []string) (exit int) {
+	units, err := findUnits(args)
+	if err != nil {
+		stderr("%v", err)
+		return 1
+	}
+	if len(units) == 0 {
+		stderr("No units were found")
+		return 1
+	}
+	for _, u := range units {
+		if job.JobState(u.CurrentState) == job.JobStateInactive && !suToGlobal(u) {
+			stderr("Unable to restart unit %s in state %s", u.Name, job.JobStateInactive)
+			return 1
+		} else if job.JobState(u.CurrentState) == job.JobStateLoaded {
+			log.Infof("Unit(%s) already %s, starting.", u.Name, job.JobStateLoaded)
+
+			exit = setUnitStateAndWait(u, job.JobStateLaunched, sharedFlags.BlockAttempts)
+			if exit == 1 {
+				return exit
+			}
+			continue
+		} else {
+			//stop and start it
+			exit = setUnitStateAndWait(u, job.JobStateLoaded, sharedFlags.BlockAttempts)
+			if exit == 1 {
+				return exit
+			}
+			exit = setUnitStateAndWait(u, job.JobStateLaunched, sharedFlags.BlockAttempts)
+			if exit == 1 {
+				return exit
+			}
+		}
+		log.Infof("Unit(%s) was restarted.", u.Name)
+	}
+	return
+}
+
+func setUnitStateAndWait(unit schema.Unit, targetState job.JobState, blockAttempts int) (exit int) {
+	cAPI.SetUnitTargetState(unit.Name, string(targetState))
+
+	if !suToGlobal(unit) {
+		errchan := waitForUnitStates([]string{unit.Name}, targetState, blockAttempts, os.Stdout)
+		for err := range errchan {
+			stderr("Error waiting for unit %s to change states: %v", unit.Name, err)
+			return 1
+		}
+	}
+	return
+}