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exec.go
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exec.go
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package driver
import (
"fmt"
"path/filepath"
"runtime"
"syscall"
"time"
"github.com/hashicorp/nomad/client/allocdir"
"github.com/hashicorp/nomad/client/config"
"github.com/hashicorp/nomad/client/driver/executor"
cstructs "github.com/hashicorp/nomad/client/driver/structs"
"github.com/hashicorp/nomad/client/fingerprint"
"github.com/hashicorp/nomad/client/getter"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/mitchellh/mapstructure"
)
// ExecDriver fork/execs tasks using as many of the underlying OS's isolation
// features.
type ExecDriver struct {
DriverContext
fingerprint.StaticFingerprinter
}
type ExecDriverConfig struct {
ArtifactSource string `mapstructure:"artifact_source"`
Checksum string `mapstructure:"checksum"`
Command string `mapstructure:"command"`
Args []string `mapstructure:"args"`
}
// execHandle is returned from Start/Open as a handle to the PID
type execHandle struct {
cmd executor.Executor
waitCh chan *cstructs.WaitResult
doneCh chan struct{}
}
// NewExecDriver is used to create a new exec driver
func NewExecDriver(ctx *DriverContext) Driver {
return &ExecDriver{DriverContext: *ctx}
}
func (d *ExecDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool, error) {
// Only enable if we are root on linux.
if runtime.GOOS != "linux" {
d.logger.Printf("[DEBUG] driver.exec: only available on linux, disabling")
return false, nil
} else if syscall.Geteuid() != 0 {
d.logger.Printf("[DEBUG] driver.exec: must run as root user, disabling")
return false, nil
}
node.Attributes["driver.exec"] = "1"
return true, nil
}
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 command == "" {
return nil, fmt.Errorf("missing command for exec driver")
}
// Create a location to download the artifact.
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)
}
// Check if an artificat is specified and attempt to download it
source, ok := task.Config["artifact_source"]
if ok && source != "" {
// Proceed to download an artifact to be executed.
_, err := getter.GetArtifact(
filepath.Join(taskDir, allocdir.TaskLocal),
driverConfig.ArtifactSource,
driverConfig.Checksum,
d.logger,
)
if err != nil {
return nil, err
}
}
// Get the environment variables.
envVars := TaskEnvironmentVariables(ctx, task)
// Setup the command
cmd := executor.Command(command, driverConfig.Args...)
if err := cmd.Limit(task.Resources); err != nil {
return nil, fmt.Errorf("failed to constrain resources: %s", err)
}
// Populate environment variables
cmd.Command().Env = envVars.List()
if err := cmd.ConfigureTaskDir(d.taskName, ctx.AllocDir); err != nil {
return nil, fmt.Errorf("failed to configure task directory: %v", err)
}
if err := cmd.Start(); err != nil {
return nil, fmt.Errorf("failed to start command: %v", err)
}
// Return a driver handle
h := &execHandle{
cmd: cmd,
doneCh: make(chan struct{}),
waitCh: make(chan *cstructs.WaitResult, 1),
}
go h.run()
return h, nil
}
func (d *ExecDriver) Open(ctx *ExecContext, handleID string) (DriverHandle, error) {
// Find the process
cmd, err := executor.OpenId(handleID)
if err != nil {
return nil, fmt.Errorf("failed to open ID %v: %v", handleID, err)
}
// Return a driver handle
h := &execHandle{
cmd: cmd,
doneCh: make(chan struct{}),
waitCh: make(chan *cstructs.WaitResult, 1),
}
go h.run()
return h, nil
}
func (h *execHandle) ID() string {
id, _ := h.cmd.ID()
return id
}
func (h *execHandle) WaitCh() chan *cstructs.WaitResult {
return h.waitCh
}
func (h *execHandle) Update(task *structs.Task) error {
// Update is not possible
return nil
}
func (h *execHandle) Kill() error {
h.cmd.Shutdown()
select {
case <-h.doneCh:
return nil
case <-time.After(5 * time.Second):
return h.cmd.ForceStop()
}
}
func (h *execHandle) run() {
res := h.cmd.Wait()
close(h.doneCh)
h.waitCh <- res
close(h.waitCh)
}