275 lines
8 KiB
Go
275 lines
8 KiB
Go
package driver
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import (
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"encoding/json"
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"fmt"
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"log"
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"os/exec"
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"path/filepath"
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"syscall"
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"time"
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"github.com/hashicorp/go-multierror"
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"github.com/hashicorp/go-plugin"
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"github.com/hashicorp/nomad/client/allocdir"
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"github.com/hashicorp/nomad/client/config"
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"github.com/hashicorp/nomad/client/driver/executor"
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cstructs "github.com/hashicorp/nomad/client/driver/structs"
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"github.com/hashicorp/nomad/client/getter"
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"github.com/hashicorp/nomad/helper/discover"
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"github.com/hashicorp/nomad/nomad/structs"
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"github.com/mitchellh/mapstructure"
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)
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// ExecDriver fork/execs tasks using as many of the underlying OS's isolation
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// features.
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type ExecDriver struct {
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DriverContext
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}
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type ExecDriverConfig struct {
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ArtifactSource string `mapstructure:"artifact_source"`
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Checksum string `mapstructure:"checksum"`
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Command string `mapstructure:"command"`
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Args []string `mapstructure:"args"`
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}
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// execHandle is returned from Start/Open as a handle to the PID
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type execHandle struct {
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pluginClient *plugin.Client
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executor executor.Executor
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isolationConfig *executor.IsolationConfig
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userPid int
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allocDir *allocdir.AllocDir
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killTimeout time.Duration
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logger *log.Logger
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waitCh chan *cstructs.WaitResult
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doneCh chan struct{}
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}
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// NewExecDriver is used to create a new exec driver
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func NewExecDriver(ctx *DriverContext) Driver {
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return &ExecDriver{DriverContext: *ctx}
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}
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func (d *ExecDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool, error) {
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// Only enable if cgroups are available and we are root
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if _, ok := node.Attributes["unique.cgroup.mountpoint"]; !ok {
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d.logger.Printf("[DEBUG] driver.exec: cgroups unavailable, disabling")
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return false, nil
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} else if syscall.Geteuid() != 0 {
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d.logger.Printf("[DEBUG] driver.exec: must run as root user, disabling")
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return false, nil
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}
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node.Attributes["driver.exec"] = "1"
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return true, nil
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}
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func (d *ExecDriver) Periodic() (bool, time.Duration) {
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return true, 15 * time.Second
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}
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func (d *ExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
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var driverConfig ExecDriverConfig
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if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
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return nil, err
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}
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// Get the command to be ran
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command := driverConfig.Command
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if command == "" {
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return nil, fmt.Errorf("missing command for exec driver")
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}
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// Create a location to download the artifact.
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taskDir, ok := ctx.AllocDir.TaskDirs[d.DriverContext.taskName]
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if !ok {
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return nil, fmt.Errorf("Could not find task directory for task: %v", d.DriverContext.taskName)
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}
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// Check if an artificat is specified and attempt to download it
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source, ok := task.Config["artifact_source"]
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if ok && source != "" {
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// Proceed to download an artifact to be executed.
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_, err := getter.GetArtifact(
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taskDir,
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driverConfig.ArtifactSource,
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driverConfig.Checksum,
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d.logger,
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)
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if err != nil {
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return nil, err
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}
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}
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bin, err := discover.NomadExecutable()
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if err != nil {
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return nil, fmt.Errorf("unable to find the nomad binary: %v", err)
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}
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pluginLogFile := filepath.Join(taskDir, fmt.Sprintf("%s-executor.out", task.Name))
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pluginConfig := &plugin.ClientConfig{
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Cmd: exec.Command(bin, "executor", pluginLogFile),
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}
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exec, pluginClient, err := createExecutor(pluginConfig, d.config.LogOutput, d.config)
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if err != nil {
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return nil, err
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}
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executorCtx := &executor.ExecutorContext{
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TaskEnv: d.taskEnv,
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AllocDir: ctx.AllocDir,
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TaskName: task.Name,
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TaskResources: task.Resources,
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ResourceLimits: true,
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FSIsolation: true,
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UnprivilegedUser: true,
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}
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ps, err := exec.LaunchCmd(&executor.ExecCommand{Cmd: command, Args: driverConfig.Args}, executorCtx)
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if err != nil {
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pluginClient.Kill()
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return nil, fmt.Errorf("error starting process via the plugin: %v", err)
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}
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d.logger.Printf("[DEBUG] driver.exec: started process via plugin with pid: %v", ps.Pid)
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// Return a driver handle
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h := &execHandle{
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pluginClient: pluginClient,
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userPid: ps.Pid,
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executor: exec,
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allocDir: ctx.AllocDir,
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isolationConfig: ps.IsolationConfig,
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killTimeout: d.DriverContext.KillTimeout(task),
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logger: d.logger,
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doneCh: make(chan struct{}),
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waitCh: make(chan *cstructs.WaitResult, 1),
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}
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go h.run()
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return h, nil
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}
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type execId struct {
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KillTimeout time.Duration
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UserPid int
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TaskDir string
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AllocDir *allocdir.AllocDir
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IsolationConfig *executor.IsolationConfig
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PluginConfig *ExecutorReattachConfig
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}
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func (d *ExecDriver) Open(ctx *ExecContext, handleID string) (DriverHandle, error) {
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id := &execId{}
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if err := json.Unmarshal([]byte(handleID), id); err != nil {
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return nil, fmt.Errorf("Failed to parse handle '%s': %v", handleID, err)
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}
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pluginConfig := &plugin.ClientConfig{
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Reattach: id.PluginConfig.PluginConfig(),
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}
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exec, client, err := createExecutor(pluginConfig, d.config.LogOutput, d.config)
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if err != nil {
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merrs := new(multierror.Error)
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merrs.Errors = append(merrs.Errors, err)
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d.logger.Println("[ERROR] driver.exec: error connecting to plugin so destroying plugin pid and user pid")
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if e := destroyPlugin(id.PluginConfig.Pid, id.UserPid); e != nil {
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merrs.Errors = append(merrs.Errors, fmt.Errorf("error destroying plugin and userpid: %v", e))
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}
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if id.IsolationConfig != nil {
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if e := executor.DestroyCgroup(id.IsolationConfig.Cgroup); e != nil {
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merrs.Errors = append(merrs.Errors, fmt.Errorf("destroying cgroup failed: %v", e))
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}
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}
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if e := ctx.AllocDir.UnmountAll(); e != nil {
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merrs.Errors = append(merrs.Errors, e)
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}
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return nil, fmt.Errorf("error connecting to plugin: %v", merrs.ErrorOrNil())
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}
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// Return a driver handle
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h := &execHandle{
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pluginClient: client,
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executor: exec,
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userPid: id.UserPid,
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allocDir: id.AllocDir,
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isolationConfig: id.IsolationConfig,
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logger: d.logger,
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killTimeout: id.KillTimeout,
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doneCh: make(chan struct{}),
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waitCh: make(chan *cstructs.WaitResult, 1),
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}
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go h.run()
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return h, nil
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}
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func (h *execHandle) ID() string {
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id := execId{
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KillTimeout: h.killTimeout,
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PluginConfig: NewExecutorReattachConfig(h.pluginClient.ReattachConfig()),
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UserPid: h.userPid,
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AllocDir: h.allocDir,
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IsolationConfig: h.isolationConfig,
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}
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data, err := json.Marshal(id)
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if err != nil {
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h.logger.Printf("[ERR] driver.exec: failed to marshal ID to JSON: %s", err)
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}
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return string(data)
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}
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func (h *execHandle) WaitCh() chan *cstructs.WaitResult {
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return h.waitCh
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}
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func (h *execHandle) Update(task *structs.Task) error {
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// Store the updated kill timeout.
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h.killTimeout = task.KillTimeout
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// Update is not possible
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return nil
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}
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func (h *execHandle) Kill() error {
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if err := h.executor.ShutDown(); err != nil {
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return fmt.Errorf("executor Shutdown failed: %v", err)
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}
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select {
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case <-h.doneCh:
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return nil
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case <-time.After(h.killTimeout):
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if h.pluginClient.Exited() {
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return nil
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}
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if err := h.executor.Exit(); err != nil {
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return fmt.Errorf("executor Exit failed: %v", err)
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}
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return nil
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}
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}
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func (h *execHandle) run() {
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ps, err := h.executor.Wait()
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close(h.doneCh)
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// If the exitcode is 0 and we had an error that means the plugin didn't
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// connect and doesn't know the state of the user process so we are killing
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// the user process so that when we create a new executor on restarting the
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// new user process doesn't have collisions with resources that the older
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// user pid might be holding onto.
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if ps.ExitCode == 0 && err != nil {
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if h.isolationConfig != nil {
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if e := executor.DestroyCgroup(h.isolationConfig.Cgroup); e != nil {
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h.logger.Printf("[ERROR] driver.exec: destroying cgroup failed while killing cgroup: %v", e)
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}
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}
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if e := h.allocDir.UnmountAll(); e != nil {
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h.logger.Printf("[ERROR] driver.exec: unmounting dev,proc and alloc dirs failed: %v", e)
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}
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}
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h.waitCh <- &cstructs.WaitResult{ExitCode: ps.ExitCode, Signal: 0,
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Err: err}
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close(h.waitCh)
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h.pluginClient.Kill()
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}
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