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exec.go
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exec.go
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package driver
import (
"encoding/json"
"fmt"
"log"
"os/exec"
"path/filepath"
"strings"
"time"
"github.com/hashicorp/go-multierror"
"github.com/hashicorp/go-plugin"
"github.com/hashicorp/nomad/client/allocdir"
"github.com/hashicorp/nomad/client/config"
"github.com/hashicorp/nomad/client/driver/executor"
dstructs "github.com/hashicorp/nomad/client/driver/structs"
cstructs "github.com/hashicorp/nomad/client/structs"
"github.com/hashicorp/nomad/helper/discover"
"github.com/hashicorp/nomad/helper/fields"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/mitchellh/mapstructure"
)
const (
// The key populated in Node Attributes to indicate the presence of the Exec
// driver
execDriverAttr = "driver.exec"
)
// ExecDriver fork/execs tasks using as many of the underlying OS's isolation
// features.
type ExecDriver struct {
DriverContext
}
type ExecDriverConfig struct {
Command string `mapstructure:"command"`
Args []string `mapstructure:"args"`
}
// execHandle is returned from Start/Open as a handle to the PID
type execHandle struct {
pluginClient *plugin.Client
executor executor.Executor
isolationConfig *dstructs.IsolationConfig
userPid int
allocDir *allocdir.AllocDir
killTimeout time.Duration
maxKillTimeout time.Duration
logger *log.Logger
waitCh chan *dstructs.WaitResult
doneCh chan struct{}
version string
}
// NewExecDriver is used to create a new exec driver
func NewExecDriver(ctx *DriverContext) Driver {
return &ExecDriver{DriverContext: *ctx}
}
// Validate is used to validate the driver configuration
func (d *ExecDriver) Validate(config map[string]interface{}) error {
fd := &fields.FieldData{
Raw: config,
Schema: map[string]*fields.FieldSchema{
"command": &fields.FieldSchema{
Type: fields.TypeString,
Required: true,
},
"args": &fields.FieldSchema{
Type: fields.TypeArray,
},
},
}
if err := fd.Validate(); err != nil {
return err
}
return nil
}
func (d *ExecDriver) Periodic() (bool, time.Duration) {
return true, 15 * time.Second
}
func (d *ExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
var driverConfig ExecDriverConfig
if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
return nil, err
}
// Get the command to be ran
command := driverConfig.Command
if err := validateCommand(command, "args"); err != nil {
return nil, err
}
// Set the host environment variables.
filter := strings.Split(d.config.ReadDefault("env.blacklist", config.DefaultEnvBlacklist), ",")
d.taskEnv.AppendHostEnvvars(filter)
// Get the task directory for storing the executor logs.
taskDir, ok := ctx.AllocDir.TaskDirs[d.DriverContext.taskName]
if !ok {
return nil, fmt.Errorf("Could not find task directory for task: %v", d.DriverContext.taskName)
}
bin, err := discover.NomadExecutable()
if err != nil {
return nil, fmt.Errorf("unable to find the nomad binary: %v", err)
}
pluginLogFile := filepath.Join(taskDir, fmt.Sprintf("%s-executor.out", task.Name))
pluginConfig := &plugin.ClientConfig{
Cmd: exec.Command(bin, "executor", pluginLogFile),
}
exec, pluginClient, err := createExecutor(pluginConfig, d.config.LogOutput, d.config)
if err != nil {
return nil, err
}
executorCtx := &executor.ExecutorContext{
TaskEnv: d.taskEnv,
Driver: "exec",
AllocDir: ctx.AllocDir,
AllocID: ctx.AllocID,
ChrootEnv: d.config.ChrootEnv,
Task: task,
}
ps, err := exec.LaunchCmd(&executor.ExecCommand{
Cmd: command,
Args: driverConfig.Args,
FSIsolation: true,
ResourceLimits: true,
User: getExecutorUser(task),
}, executorCtx)
if err != nil {
pluginClient.Kill()
return nil, err
}
d.logger.Printf("[DEBUG] driver.exec: started process via plugin with pid: %v", ps.Pid)
// Return a driver handle
maxKill := d.DriverContext.config.MaxKillTimeout
h := &execHandle{
pluginClient: pluginClient,
userPid: ps.Pid,
executor: exec,
allocDir: ctx.AllocDir,
isolationConfig: ps.IsolationConfig,
killTimeout: GetKillTimeout(task.KillTimeout, maxKill),
maxKillTimeout: maxKill,
logger: d.logger,
version: d.config.Version,
doneCh: make(chan struct{}),
waitCh: make(chan *dstructs.WaitResult, 1),
}
if err := exec.SyncServices(consulContext(d.config, "")); err != nil {
d.logger.Printf("[ERR] driver.exec: error registering services with consul for task: %q: %v", task.Name, err)
}
go h.run()
return h, nil
}
type execId struct {
Version string
KillTimeout time.Duration
MaxKillTimeout time.Duration
UserPid int
TaskDir string
AllocDir *allocdir.AllocDir
IsolationConfig *dstructs.IsolationConfig
PluginConfig *PluginReattachConfig
}
func (d *ExecDriver) Open(ctx *ExecContext, handleID string) (DriverHandle, error) {
id := &execId{}
if err := json.Unmarshal([]byte(handleID), id); err != nil {
return nil, fmt.Errorf("Failed to parse handle '%s': %v", handleID, err)
}
pluginConfig := &plugin.ClientConfig{
Reattach: id.PluginConfig.PluginConfig(),
}
exec, client, err := createExecutor(pluginConfig, d.config.LogOutput, d.config)
if err != nil {
merrs := new(multierror.Error)
merrs.Errors = append(merrs.Errors, err)
d.logger.Println("[ERR] driver.exec: error connecting to plugin so destroying plugin pid and user pid")
if e := destroyPlugin(id.PluginConfig.Pid, id.UserPid); e != nil {
merrs.Errors = append(merrs.Errors, fmt.Errorf("error destroying plugin and userpid: %v", e))
}
if id.IsolationConfig != nil {
ePid := pluginConfig.Reattach.Pid
if e := executor.ClientCleanup(id.IsolationConfig, ePid); e != nil {
merrs.Errors = append(merrs.Errors, fmt.Errorf("destroying cgroup failed: %v", e))
}
}
if e := ctx.AllocDir.UnmountAll(); e != nil {
merrs.Errors = append(merrs.Errors, e)
}
return nil, fmt.Errorf("error connecting to plugin: %v", merrs.ErrorOrNil())
}
ver, _ := exec.Version()
d.logger.Printf("[DEBUG] driver.exec : version of executor: %v", ver.Version)
// Return a driver handle
h := &execHandle{
pluginClient: client,
executor: exec,
userPid: id.UserPid,
allocDir: id.AllocDir,
isolationConfig: id.IsolationConfig,
logger: d.logger,
version: id.Version,
killTimeout: id.KillTimeout,
maxKillTimeout: id.MaxKillTimeout,
doneCh: make(chan struct{}),
waitCh: make(chan *dstructs.WaitResult, 1),
}
if err := exec.SyncServices(consulContext(d.config, "")); err != nil {
d.logger.Printf("[ERR] driver.exec: error registering services with consul: %v", err)
}
go h.run()
return h, nil
}
func (h *execHandle) ID() string {
id := execId{
Version: h.version,
KillTimeout: h.killTimeout,
MaxKillTimeout: h.maxKillTimeout,
PluginConfig: NewPluginReattachConfig(h.pluginClient.ReattachConfig()),
UserPid: h.userPid,
AllocDir: h.allocDir,
IsolationConfig: h.isolationConfig,
}
data, err := json.Marshal(id)
if err != nil {
h.logger.Printf("[ERR] driver.exec: failed to marshal ID to JSON: %s", err)
}
return string(data)
}
func (h *execHandle) WaitCh() chan *dstructs.WaitResult {
return h.waitCh
}
func (h *execHandle) Update(task *structs.Task) error {
// Store the updated kill timeout.
h.killTimeout = GetKillTimeout(task.KillTimeout, h.maxKillTimeout)
h.executor.UpdateTask(task)
// Update is not possible
return nil
}
func (h *execHandle) Kill() error {
if err := h.executor.ShutDown(); err != nil {
if h.pluginClient.Exited() {
return nil
}
return fmt.Errorf("executor Shutdown failed: %v", err)
}
select {
case <-h.doneCh:
return nil
case <-time.After(h.killTimeout):
if h.pluginClient.Exited() {
return nil
}
if err := h.executor.Exit(); err != nil {
return fmt.Errorf("executor Exit failed: %v", err)
}
return nil
}
}
func (h *execHandle) Stats() (*cstructs.TaskResourceUsage, error) {
return h.executor.Stats()
}
func (h *execHandle) run() {
ps, err := h.executor.Wait()
close(h.doneCh)
// If the exitcode is 0 and we had an error that means the plugin didn't
// connect and doesn't know the state of the user process so we are killing
// the user process so that when we create a new executor on restarting the
// new user process doesn't have collisions with resources that the older
// user pid might be holding onto.
if ps.ExitCode == 0 && err != nil {
if h.isolationConfig != nil {
ePid := h.pluginClient.ReattachConfig().Pid
if e := executor.ClientCleanup(h.isolationConfig, ePid); e != nil {
h.logger.Printf("[ERR] driver.exec: destroying resource container failed: %v", e)
}
}
if e := h.allocDir.UnmountAll(); e != nil {
h.logger.Printf("[ERR] driver.exec: unmounting dev,proc and alloc dirs failed: %v", e)
}
}
h.waitCh <- dstructs.NewWaitResult(ps.ExitCode, ps.Signal, err)
close(h.waitCh)
// Remove services
if err := h.executor.DeregisterServices(); err != nil {
h.logger.Printf("[ERR] driver.exec: failed to deregister services: %v", err)
}
if err := h.executor.Exit(); err != nil {
h.logger.Printf("[ERR] driver.exec: error destroying executor: %v", err)
}
h.pluginClient.Kill()
}