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Qemu driver: tweaks in response to PR feedback
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Remove attribute for long qemu monitor path; misc cleanup; update tests
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@cheeseprocedure
cheeseprocedure committed Nov 3, 2017
1 parent 1856585 commit 66f9840
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Showing 2 changed files with 163 additions and 57 deletions.
100 changes: 54 additions & 46 deletions client/driver/qemu.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,18 +29,26 @@ import (

var (
reQemuVersion = regexp.MustCompile(`version (\d[\.\d+]+)`)

// Prior to qemu 2.10.1, monitor socket paths are truncated to 108 bytes.
// We should consider this if driver.qemu.version is < 2.10.1 and the
// generated monitor path is too long.
//
// Relevant fix is here:
// https://github.com/qemu/qemu/commit/ad9579aaa16d5b385922d49edac2c96c79bcfb6
qemuVersionLongSocketPathFix = semver.New("2.10.1")
)

const (
// The key populated in Node Attributes to indicate presence of the Qemu driver
qemuDriverAttr = "driver.qemu"
qemuDriverVersionAttr = "driver.qemu.version"
qemuDriverLongMonitorPathAttr = "driver.qemu.longsocketpaths"
qemuDriverAttr = "driver.qemu"
qemuDriverVersionAttr = "driver.qemu.version"
// Represents an ACPI shutdown request to the VM (emulates pressing a physical power button)
// Reference: https://en.wikibooks.org/wiki/QEMU/Monitor
qemuGracefulShutdownMsg = "system_powerdown\n"
legacyMaxMonitorPathLen = 108
qemuMonitorSocketName = "qemu-monitor.sock"
// Maximum socket path length prior to qemu 2.10.1
qemuLegacyMaxMonitorPathLen = 108
)

// QemuDriver is a driver for running images via Qemu
Expand Down Expand Up @@ -75,11 +83,27 @@ type qemuHandle struct {
doneCh chan struct{}
}

func getMonitorPath(dir string, longPathSupport string) (string, error) {
if len(dir) > legacyMaxMonitorPathLen && longPathSupport != "1" {
return "", fmt.Errorf("monitor path is too long")
// getMonitorPath is used to determine whether a qemu monitor socket can be
// safely created and accessed in the task directory by the version of qemu
// present on the host. If it is safe to use, the socket's full path is
// returned along with a nil error. Otherwise, an empty string is returned
// along with a descriptive error.
func (d *QemuDriver) getMonitorPath(dir string) (string, error) {
var longPathSupport bool
currentQemuVer := d.DriverContext.node.Attributes[qemuDriverVersionAttr]
currentQemuSemver := semver.New(currentQemuVer)
if currentQemuSemver.LessThan(*qemuVersionLongSocketPathFix) {
longPathSupport = false
d.logger.Printf("[DEBUG] driver.qemu: long socket paths are not available in this version of QEMU (%s)", currentQemuVer)
} else {
longPathSupport = true
d.logger.Printf("[DEBUG] driver.qemu: long socket paths available in this version of QEMU (%s)", currentQemuVer)
}
fullSocketPath := fmt.Sprintf("%s/%s", dir, qemuMonitorSocketName)
if len(fullSocketPath) > qemuLegacyMaxMonitorPathLen && longPathSupport == false {
return "", fmt.Errorf("monitor path is too long for this version of qemu")
}
return fmt.Sprintf("%s/%s", dir, qemuMonitorSocketName), nil
return fullSocketPath, nil
}

// NewQemuDriver is used to create a new exec driver
Expand Down Expand Up @@ -154,21 +178,6 @@ func (d *QemuDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool,
node.Attributes[qemuDriverAttr] = "1"
node.Attributes[qemuDriverVersionAttr] = currentQemuVersion

// Prior to qemu 2.10.1, monitor socket paths are truncated to 108 bytes.
// We should consider this if driver.qemu.version is < 2.10.1 and the
// generated monitor path is too long.
//
// Relevant fix is here:
// https://github.com/qemu/qemu/commit/ad9579aaa16d5b385922d49edac2c96c79bcfb6
currentQemuSemver := semver.New(currentQemuVersion)
fixedSocketPathLenVer := semver.New("2.10.1")
if currentQemuSemver.LessThan(*fixedSocketPathLenVer) {
node.Attributes[qemuDriverLongMonitorPathAttr] = "0"
d.logger.Printf("[DEBUG] driver.qemu: long socket paths are not available in this version of QEMU (%s)", currentQemuVersion)
} else {
d.logger.Printf("[DEBUG] driver.qemu: long socket paths available in this version of QEMU (%s)", currentQemuVersion)
node.Attributes[qemuDriverLongMonitorPathAttr] = "1"
}
return true, nil
}

Expand Down Expand Up @@ -233,13 +242,13 @@ func (d *QemuDriver) Start(ctx *ExecContext, task *structs.Task) (*StartResponse
if d.driverConfig.GracefulShutdown {
// This socket will be used to manage the virtual machine (for example,
// to perform graceful shutdowns)
monitorPath, err = getMonitorPath(ctx.TaskDir.Dir, ctx.TaskEnv.NodeAttrs[qemuDriverLongMonitorPathAttr])
if err == nil {
d.logger.Printf("[DEBUG] driver.qemu: got monitor path OK: %s", monitorPath)
args = append(args, "-monitor", fmt.Sprintf("unix:%s,server,nowait", monitorPath))
} else {
d.logger.Printf("[WARN] driver.qemu: %s", err)
monitorPath, err := d.getMonitorPath(ctx.TaskDir.Dir)
if err != nil {
d.logger.Printf("[ERR] driver.qemu: could not get qemu monitor path - error: %s", err)
return nil, err
}
d.logger.Printf("[DEBUG] driver.qemu: got monitor path OK: %s", monitorPath)
args = append(args, "-monitor", fmt.Sprintf("unix:%s,server,nowait", monitorPath))
}

// Add pass through arguments to qemu executable. A user can specify
Expand Down Expand Up @@ -436,11 +445,9 @@ func (h *qemuHandle) Signal(s os.Signal) error {

func (h *qemuHandle) Kill() error {
// First, try sending a graceful shutdown command via the qemu monitor
err := sendQemuShutdown(h.logger, h.monitorPath, h.userPid)

// If we did not send a graceful shutdown via the monitor socket, we'll
// issue an interrupt to the qemu process as a last resort
if err != nil {
if err := sendQemuShutdown(h.logger, h.monitorPath, h.userPid); err != nil {
h.logger.Printf("[DEBUG] driver.qemu: error sending graceful shutdown for user process pid %d: %s", h.userPid, err)
// Issue an interrupt to the qemu process as a last resort
if err := h.executor.ShutDown(); err != nil {
if h.pluginClient.Exited() {
return nil
Expand Down Expand Up @@ -490,22 +497,23 @@ func (h *qemuHandle) run() {
close(h.waitCh)
}

// sendQemuShutdown attempts to issue an ACPI power-off command via the qemu
// monitor
func sendQemuShutdown(logger *log.Logger, monitorPath string, userPid int) error {
if monitorPath == "" {
logger.Printf("[DEBUG] driver.qemu: monitorPath not set; will not attempt graceful shutdown for user process pid %d", userPid)
return errors.New("monitorPath not set")
} else {
monitorSocket, err := net.Dial("unix", monitorPath)
if err == nil {
defer monitorSocket.Close()
logger.Printf("[DEBUG] driver.qemu: sending graceful shutdown command to qemu monitor socket %q for user process pid %d", monitorPath, userPid)
_, err = monitorSocket.Write([]byte(qemuGracefulShutdownMsg))
if err != nil {
logger.Printf("[WARN] driver.qemu: failed to send shutdown message %q to monitor socket %q for user process pid %d: %s", qemuGracefulShutdownMsg, monitorPath, userPid, err)
}
} else {
logger.Printf("[WARN] driver.qemu: could not connect to qemu monitor %q for user process pid %d: %s", monitorPath, userPid, err)
}
}
monitorSocket, err := net.Dial("unix", monitorPath)
if err != nil {
logger.Printf("[WARN] driver.qemu: could not connect to qemu monitor %q for user process pid %d: %s", monitorPath, userPid, err)
return err
}
defer monitorSocket.Close()
logger.Printf("[DEBUG] driver.qemu: sending graceful shutdown command to qemu monitor socket %q for user process pid %d", monitorPath, userPid)
_, err = monitorSocket.Write([]byte(qemuGracefulShutdownMsg))
if err != nil {
logger.Printf("[WARN] driver.qemu: failed to send shutdown message %q to monitor socket %q for user process pid %d: %s", qemuGracefulShutdownMsg, monitorPath, userPid, err)
}
return err
}
120 changes: 109 additions & 11 deletions client/driver/qemu_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,9 +47,6 @@ func TestQemuDriver_Fingerprint(t *testing.T) {
if node.Attributes[qemuDriverVersionAttr] == "" {
t.Fatalf("Missing Qemu driver version")
}
if node.Attributes[qemuDriverLongMonitorPathAttr] == "" {
t.Fatalf("Missing Qemu long monitor socket path support flag")
}
}

func TestQemuDriver_StartOpen_Wait(t *testing.T) {
Expand Down Expand Up @@ -145,7 +142,7 @@ func TestQemuDriver_GracefulShutdown(t *testing.T) {
},
// With the use of tcg acceleration, it's very unlikely a qemu instance
// will boot (and gracefully halt) in a reasonable amount of time, so
// this timeout is kept low to reduce test execution time
// this timeout is kept low to reduce test execution time.
KillTimeout: time.Duration(1 * time.Second),
LogConfig: &structs.LogConfig{
MaxFiles: 10,
Expand All @@ -166,6 +163,14 @@ func TestQemuDriver_GracefulShutdown(t *testing.T) {
defer ctx.AllocDir.Destroy()
d := NewQemuDriver(ctx.DriverCtx)

apply, err := d.Fingerprint(&config.Config{}, ctx.DriverCtx.node)
if err != nil {
t.Fatalf("err: %v", err)
}
if !apply {
t.Fatalf("should apply")
}

dst := ctx.ExecCtx.TaskDir.Dir

copyFile("./test-resources/qemu/linux-0.2.img", filepath.Join(dst, "linux-0.2.img"), t)
Expand Down Expand Up @@ -304,25 +309,118 @@ func TestQemuDriverUser(t *testing.T) {
}
}

func TestQemuDriverGetMonitorPath(t *testing.T) {
func TestQemuDriverGetMonitorPathOldQemu(t *testing.T) {
task := &structs.Task{
Name: "linux",
Driver: "qemu",
Config: map[string]interface{}{
"image_path": "linux-0.2.img",
"accelerator": "tcg",
"graceful_shutdown": true,
"port_map": []map[string]int{{
"main": 22,
"web": 8080,
}},
"args": []string{"-nodefconfig", "-nodefaults"},
},
KillTimeout: time.Duration(1 * time.Second),
LogConfig: &structs.LogConfig{
MaxFiles: 10,
MaxFileSizeMB: 10,
},
Resources: &structs.Resources{
CPU: 500,
MemoryMB: 512,
Networks: []*structs.NetworkResource{
{
ReservedPorts: []structs.Port{{Label: "main", Value: 22000}, {Label: "web", Value: 80}},
},
},
},
}

ctx := testDriverContexts(t, task)
defer ctx.AllocDir.Destroy()

// Simulate an older version of qemu which does not support long monitor socket paths
ctx.DriverCtx.node.Attributes[qemuDriverVersionAttr] = "2.0.0"

d := &QemuDriver{DriverContext: *ctx.DriverCtx}

shortPath := strings.Repeat("x", 10)
_, err := getMonitorPath(shortPath, "0")
_, err := d.getMonitorPath(shortPath)
if err != nil {
t.Fatal("Should not have returned an error")
}

longPath := strings.Repeat("x", legacyMaxMonitorPathLen+100)
_, err = getMonitorPath(longPath, "0")
longPath := strings.Repeat("x", qemuLegacyMaxMonitorPathLen+100)
_, err = d.getMonitorPath(longPath)
if err == nil {
t.Fatal("Should have returned an error")
}
_, err = getMonitorPath(longPath, "1")

// Max length includes the '/' separator and socket name
maxLengthCount := qemuLegacyMaxMonitorPathLen - len(qemuMonitorSocketName) - 1
maxLengthLegacyPath := strings.Repeat("x", maxLengthCount)
_, err = d.getMonitorPath(maxLengthLegacyPath)
if err != nil {
t.Fatalf("Should not have returned an error: %s", err)
}
}

func TestQemuDriverGetMonitorPathNewQemu(t *testing.T) {
task := &structs.Task{
Name: "linux",
Driver: "qemu",
Config: map[string]interface{}{
"image_path": "linux-0.2.img",
"accelerator": "tcg",
"graceful_shutdown": true,
"port_map": []map[string]int{{
"main": 22,
"web": 8080,
}},
"args": []string{"-nodefconfig", "-nodefaults"},
},
KillTimeout: time.Duration(1 * time.Second),
LogConfig: &structs.LogConfig{
MaxFiles: 10,
MaxFileSizeMB: 10,
},
Resources: &structs.Resources{
CPU: 500,
MemoryMB: 512,
Networks: []*structs.NetworkResource{
{
ReservedPorts: []structs.Port{{Label: "main", Value: 22000}, {Label: "web", Value: 80}},
},
},
},
}

ctx := testDriverContexts(t, task)
defer ctx.AllocDir.Destroy()

// Simulate a version of qemu which supports long monitor socket paths
ctx.DriverCtx.node.Attributes[qemuDriverVersionAttr] = "2.99.99"

d := &QemuDriver{DriverContext: *ctx.DriverCtx}

shortPath := strings.Repeat("x", 10)
_, err := d.getMonitorPath(shortPath)
if err != nil {
t.Fatal("Should not have returned an error")
}

longPath := strings.Repeat("x", qemuLegacyMaxMonitorPathLen+100)
_, err = d.getMonitorPath(longPath)
if err != nil {
t.Fatal("Should not have returned an error")
}

maxLengthPath := strings.Repeat("x", legacyMaxMonitorPathLen)
_, err = getMonitorPath(maxLengthPath, "0")
maxLengthCount := qemuLegacyMaxMonitorPathLen - len(qemuMonitorSocketName) - 1
maxLengthLegacyPath := strings.Repeat("x", maxLengthCount)
_, err = d.getMonitorPath(maxLengthLegacyPath)
if err != nil {
t.Fatal("Should not have returned an error")
}
Expand Down

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