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Diffstat (limited to 'hello/driver.go')
| -rw-r--r-- | hello/driver.go | 640 |
1 files changed, 640 insertions, 0 deletions
diff --git a/hello/driver.go b/hello/driver.go new file mode 100644 index 0000000..312cb76 --- /dev/null +++ b/hello/driver.go @@ -0,0 +1,640 @@ +package hello + +import ( + "context" + "errors" + "fmt" + "os" + "os/exec" + "path/filepath" + "regexp" + "time" + + "github.com/hashicorp/consul-template/signals" + "github.com/hashicorp/go-hclog" + "github.com/hashicorp/nomad/drivers/shared/eventer" + "github.com/hashicorp/nomad/drivers/shared/executor" + "github.com/hashicorp/nomad/plugins/base" + "github.com/hashicorp/nomad/plugins/drivers" + "github.com/hashicorp/nomad/plugins/shared/hclspec" + "github.com/hashicorp/nomad/plugins/shared/structs" +) + +const ( + // pluginName is the name of the plugin + // this is used for logging and (along with the version) for uniquely + // identifying plugin binaries fingerprinted by the client + pluginName = "hello-world-example" + + // pluginVersion allows the client to identify and use newer versions of + // an installed plugin + pluginVersion = "v0.1.0" + + // fingerprintPeriod is the interval at which the plugin will send + // fingerprint responses + fingerprintPeriod = 30 * time.Second + + // taskHandleVersion is the version of task handle which this plugin sets + // and understands how to decode + // this is used to allow modification and migration of the task schema + // used by the plugin + taskHandleVersion = 1 +) + +var ( + // pluginInfo describes the plugin + pluginInfo = &base.PluginInfoResponse{ + Type: base.PluginTypeDriver, + PluginApiVersions: []string{drivers.ApiVersion010}, + PluginVersion: pluginVersion, + Name: pluginName, + } + + // configSpec is the specification of the plugin's configuration + // this is used to validate the configuration specified for the plugin + // on the client. + // this is not global, but can be specified on a per-client basis. + configSpec = hclspec.NewObject(map[string]*hclspec.Spec{ + // TODO: define plugin's agent configuration schema. + // + // The schema should be defined using HCL specs and it will be used to + // validate the agent configuration provided by the user in the + // `plugin` stanza (https://www.nomadproject.io/docs/configuration/plugin.html). + // + // For example, for the schema below a valid configuration would be: + // + // plugin "hello-driver-plugin" { + // config { + // shell = "fish" + // } + // } + "shell": hclspec.NewDefault( + hclspec.NewAttr("shell", "string", false), + hclspec.NewLiteral(`"bash"`), + ), + }) + + // taskConfigSpec is the specification of the plugin's configuration for + // a task + // this is used to validated the configuration specified for the plugin + // when a job is submitted. + taskConfigSpec = hclspec.NewObject(map[string]*hclspec.Spec{ + // TODO: define plugin's task configuration schema + // + // The schema should be defined using HCL specs and it will be used to + // validate the task configuration provided by the user when they + // submit a job. + // + // For example, for the schema below a valid task would be: + // job "example" { + // group "example" { + // task "say-hi" { + // driver = "hello-driver-plugin" + // config { + // greeting = "Hi" + // } + // } + // } + // } + "greeting": hclspec.NewDefault( + hclspec.NewAttr("greeting", "string", false), + hclspec.NewLiteral(`"Hello, World!"`), + ), + }) + + // capabilities indicates what optional features this driver supports + // this should be set according to the target run time. + capabilities = &drivers.Capabilities{ + // TODO: set plugin's capabilities + // + // The plugin's capabilities signal Nomad which extra functionalities + // are supported. For a list of available options check the docs page: + // https://godoc.org/github.com/hashicorp/nomad/plugins/drivers#Capabilities + SendSignals: true, + Exec: false, + } +) + +// Config contains configuration information for the plugin +type Config struct { + // TODO: create decoded plugin configuration struct + // + // This struct is the decoded version of the schema defined in the + // configSpec variable above. It's used to convert the HCL configuration + // passed by the Nomad agent into Go contructs. + Shell string `codec:"shell"` +} + +// TaskConfig contains configuration information for a task that runs with +// this plugin +type TaskConfig struct { + // TODO: create decoded plugin task configuration struct + // + // This struct is the decoded version of the schema defined in the + // taskConfigSpec variable above. It's used to convert the string + // configuration for the task into Go contructs. + Greeting string `codec:"greeting"` +} + +// TaskState is the runtime state which is encoded in the handle returned to +// Nomad client. +// This information is needed to rebuild the task state and handler during +// recovery. +type TaskState struct { + ReattachConfig *structs.ReattachConfig + TaskConfig *drivers.TaskConfig + StartedAt time.Time + + // TODO: add any extra important values that must be persisted in order + // to restore a task. + // + // The plugin keeps track of its running tasks in a in-memory data + // structure. If the plugin crashes, this data will be lost, so Nomad + // will respawn a new instance of the plugin and try to restore its + // in-memory representation of the running tasks using the RecoverTask() + // method below. + Pid int +} + +// HelloDriverPlugin is an example driver plugin. When provisioned in a job, +// the taks will output a greet specified by the user. +type HelloDriverPlugin struct { + // eventer is used to handle multiplexing of TaskEvents calls such that an + // event can be broadcast to all callers + eventer *eventer.Eventer + + // config is the plugin configuration set by the SetConfig RPC + config *Config + + // nomadConfig is the client config from Nomad + nomadConfig *base.ClientDriverConfig + + // tasks is the in memory datastore mapping taskIDs to driver handles + tasks *taskStore + + // ctx is the context for the driver. It is passed to other subsystems to + // coordinate shutdown + ctx context.Context + + // signalShutdown is called when the driver is shutting down and cancels + // the ctx passed to any subsystems + signalShutdown context.CancelFunc + + // logger will log to the Nomad agent + logger hclog.Logger +} + +// NewPlugin returns a new example driver plugin +func NewPlugin(logger hclog.Logger) drivers.DriverPlugin { + ctx, cancel := context.WithCancel(context.Background()) + logger = logger.Named(pluginName) + + return &HelloDriverPlugin{ + eventer: eventer.NewEventer(ctx, logger), + config: &Config{}, + tasks: newTaskStore(), + ctx: ctx, + signalShutdown: cancel, + logger: logger, + } +} + +// PluginInfo returns information describing the plugin. +func (d *HelloDriverPlugin) PluginInfo() (*base.PluginInfoResponse, error) { + return pluginInfo, nil +} + +// ConfigSchema returns the plugin configuration schema. +func (d *HelloDriverPlugin) ConfigSchema() (*hclspec.Spec, error) { + return configSpec, nil +} + +// SetConfig is called by the client to pass the configuration for the plugin. +func (d *HelloDriverPlugin) SetConfig(cfg *base.Config) error { + var config Config + if len(cfg.PluginConfig) != 0 { + if err := base.MsgPackDecode(cfg.PluginConfig, &config); err != nil { + return err + } + } + + // Save the configuration to the plugin + d.config = &config + + // TODO: parse and validated any configuration value if necessary. + // + // If your driver agent configuration requires any complex validation + // (some dependency between attributes) or special data parsing (the + // string "10s" into a time.Interval) you can do it here and update the + // value in d.config. + // + // In the example below we check if the shell specified by the user is + // supported by the plugin. + shell := d.config.Shell + if shell != "bash" && shell != "fish" { + return fmt.Errorf("invalid shell %s", d.config.Shell) + } + + // Save the Nomad agent configuration + if cfg.AgentConfig != nil { + d.nomadConfig = cfg.AgentConfig.Driver + } + + // TODO: initialize any extra requirements if necessary. + // + // Here you can use the config values to initialize any resources that are + // shared by all tasks that use this driver, such as a daemon process. + + return nil +} + +// TaskConfigSchema returns the HCL schema for the configuration of a task. +func (d *HelloDriverPlugin) TaskConfigSchema() (*hclspec.Spec, error) { + return taskConfigSpec, nil +} + +// Capabilities returns the features supported by the driver. +func (d *HelloDriverPlugin) Capabilities() (*drivers.Capabilities, error) { + return capabilities, nil +} + +// Fingerprint returns a channel that will be used to send health information +// and other driver specific node attributes. +func (d *HelloDriverPlugin) Fingerprint(ctx context.Context) (<-chan *drivers.Fingerprint, error) { + ch := make(chan *drivers.Fingerprint) + go d.handleFingerprint(ctx, ch) + return ch, nil +} + +// handleFingerprint manages the channel and the flow of fingerprint data. +func (d *HelloDriverPlugin) handleFingerprint(ctx context.Context, ch chan<- *drivers.Fingerprint) { + defer close(ch) + + // Nomad expects the initial fingerprint to be sent immediately + ticker := time.NewTimer(0) + for { + select { + case <-ctx.Done(): + return + case <-d.ctx.Done(): + return + case <-ticker.C: + // after the initial fingerprint we can set the proper fingerprint + // period + ticker.Reset(fingerprintPeriod) + ch <- d.buildFingerprint() + } + } +} + +// buildFingerprint returns the driver's fingerprint data +func (d *HelloDriverPlugin) buildFingerprint() *drivers.Fingerprint { + fp := &drivers.Fingerprint{ + Attributes: map[string]*structs.Attribute{}, + Health: drivers.HealthStateHealthy, + HealthDescription: drivers.DriverHealthy, + } + + // TODO: implement fingerprinting logic to populate health and driver + // attributes. + // + // Fingerprinting is used by the plugin to relay two important information + // to Nomad: health state and node attributes. + // + // If the plugin reports to be unhealthy, or doesn't send any fingerprint + // data in the expected interval of time, Nomad will restart it. + // + // Node attributes can be used to report any relevant information about + // the node in which the plugin is running (specific library availability, + // installed versions of a software etc.). These attributes can then be + // used by an operator to set job constrains. + // + // In the example below we check if the shell specified by the user exists + // in the node. + shell := d.config.Shell + + cmd := exec.Command("which", shell) + if err := cmd.Run(); err != nil { + return &drivers.Fingerprint{ + Health: drivers.HealthStateUndetected, + HealthDescription: fmt.Sprintf("shell %s not found", shell), + } + } + + // We also set the shell and its version as attributes + cmd = exec.Command(shell, "--version") + if out, err := cmd.Output(); err != nil { + d.logger.Warn("failed to find shell version: %v", err) + } else { + re := regexp.MustCompile("[0-9]\\.[0-9]\\.[0-9]") + version := re.FindString(string(out)) + + fp.Attributes["driver.hello.shell_version"] = structs.NewStringAttribute(version) + fp.Attributes["driver.hello.shell"] = structs.NewStringAttribute(shell) + } + + return fp +} + +// StartTask returns a task handle and a driver network if necessary. +func (d *HelloDriverPlugin) StartTask(cfg *drivers.TaskConfig) (*drivers.TaskHandle, *drivers.DriverNetwork, error) { + if _, ok := d.tasks.Get(cfg.ID); ok { + return nil, nil, fmt.Errorf("task with ID %q already started", cfg.ID) + } + + var driverConfig TaskConfig + if err := cfg.DecodeDriverConfig(&driverConfig); err != nil { + return nil, nil, fmt.Errorf("failed to decode driver config: %v", err) + } + + d.logger.Info("starting task", "driver_cfg", hclog.Fmt("%+v", driverConfig)) + handle := drivers.NewTaskHandle(taskHandleVersion) + handle.Config = cfg + + // TODO: implement driver specific mechanism to start the task. + // + // Once the task is started you will need to store any relevant runtime + // information in a taskHandle and TaskState. The taskHandle will be + // stored in-memory in the plugin and will be used to interact with the + // task. + // + // The TaskState will be returned to the Nomad client inside a + // drivers.TaskHandle instance. This TaskHandle will be sent back to plugin + // if the task ever needs to be recovered, so the TaskState should contain + // enough information to handle that. + // + // In the example below we use an executor to fork a process to run our + // greeter. The executor is then stored in the handle so we can access it + // later and the the plugin.Client is used to generate a reattach + // configuration that can be used to recover communication with the task. + executorConfig := &executor.ExecutorConfig{ + LogFile: filepath.Join(cfg.TaskDir().Dir, "executor.out"), + LogLevel: "debug", + } + + exec, pluginClient, err := executor.CreateExecutor(d.logger, d.nomadConfig, executorConfig) + if err != nil { + return nil, nil, fmt.Errorf("failed to create executor: %v", err) + } + + echoCmd := fmt.Sprintf(`echo "%s"`, driverConfig.Greeting) + execCmd := &executor.ExecCommand{ + Cmd: d.config.Shell, + Args: []string{"-c", echoCmd}, + StdoutPath: cfg.StdoutPath, + StderrPath: cfg.StderrPath, + } + + ps, err := exec.Launch(execCmd) + if err != nil { + pluginClient.Kill() + return nil, nil, fmt.Errorf("failed to launch command with executor: %v", err) + } + + h := &taskHandle{ + exec: exec, + pid: ps.Pid, + pluginClient: pluginClient, + taskConfig: cfg, + procState: drivers.TaskStateRunning, + startedAt: time.Now().Round(time.Millisecond), + logger: d.logger, + } + + driverState := TaskState{ + ReattachConfig: structs.ReattachConfigFromGoPlugin(pluginClient.ReattachConfig()), + Pid: ps.Pid, + TaskConfig: cfg, + StartedAt: h.startedAt, + } + + if err := handle.SetDriverState(&driverState); err != nil { + return nil, nil, fmt.Errorf("failed to set driver state: %v", err) + } + + d.tasks.Set(cfg.ID, h) + go h.run() + return handle, nil, nil +} + +// RecoverTask recreates the in-memory state of a task from a TaskHandle. +func (d *HelloDriverPlugin) RecoverTask(handle *drivers.TaskHandle) error { + if handle == nil { + return errors.New("error: handle cannot be nil") + } + + if _, ok := d.tasks.Get(handle.Config.ID); ok { + return nil + } + + var taskState TaskState + if err := handle.GetDriverState(&taskState); err != nil { + return fmt.Errorf("failed to decode task state from handle: %v", err) + } + + var driverConfig TaskConfig + if err := taskState.TaskConfig.DecodeDriverConfig(&driverConfig); err != nil { + return fmt.Errorf("failed to decode driver config: %v", err) + } + + // TODO: implement driver specific logic to recover a task. + // + // Recovering a task involves recreating and storing a taskHandle as if the + // task was just started. + // + // In the example below we use the executor to re-attach to the process + // that was created when the task first started. + plugRC, err := structs.ReattachConfigToGoPlugin(taskState.ReattachConfig) + if err != nil { + return fmt.Errorf("failed to build ReattachConfig from taskConfig state: %v", err) + } + + execImpl, pluginClient, err := executor.ReattachToExecutor(plugRC, d.logger) + if err != nil { + return fmt.Errorf("failed to reattach to executor: %v", err) + } + + h := &taskHandle{ + exec: execImpl, + pid: taskState.Pid, + pluginClient: pluginClient, + taskConfig: taskState.TaskConfig, + procState: drivers.TaskStateRunning, + startedAt: taskState.StartedAt, + exitResult: &drivers.ExitResult{}, + } + + d.tasks.Set(taskState.TaskConfig.ID, h) + + go h.run() + return nil +} + +// WaitTask returns a channel used to notify Nomad when a task exits. +func (d *HelloDriverPlugin) WaitTask(ctx context.Context, taskID string) (<-chan *drivers.ExitResult, error) { + handle, ok := d.tasks.Get(taskID) + if !ok { + return nil, drivers.ErrTaskNotFound + } + + ch := make(chan *drivers.ExitResult) + go d.handleWait(ctx, handle, ch) + return ch, nil +} + +func (d *HelloDriverPlugin) handleWait(ctx context.Context, handle *taskHandle, ch chan *drivers.ExitResult) { + defer close(ch) + var result *drivers.ExitResult + + // TODO: implement driver specific logic to notify Nomad the task has been + // completed and what was the exit result. + // + // When a result is sent in the result channel Nomad will stop the task and + // emit an event that an operator can use to get an insight on why the task + // stopped. + // + // In the example below we block and wait until the executor finishes + // running, at which point we send the exit code and signal in the result + // channel. + ps, err := handle.exec.Wait(ctx) + if err != nil { + result = &drivers.ExitResult{ + Err: fmt.Errorf("executor: error waiting on process: %v", err), + } + } else { + result = &drivers.ExitResult{ + ExitCode: ps.ExitCode, + Signal: ps.Signal, + } + } + + for { + select { + case <-ctx.Done(): + return + case <-d.ctx.Done(): + return + case ch <- result: + } + } +} + +// StopTask stops a running task with the given signal and within the timeout window. +func (d *HelloDriverPlugin) StopTask(taskID string, timeout time.Duration, signal string) error { + handle, ok := d.tasks.Get(taskID) + if !ok { + return drivers.ErrTaskNotFound + } + + // TODO: implement driver specific logic to stop a task. + // + // The StopTask function is expected to stop a running task by sending the + // given signal to it. If the task does not stop during the given timeout, + // the driver must forcefully kill the task. + // + // In the example below we let the executor handle the task shutdown + // process for us, but you might need to customize this for your own + // implementation. + if err := handle.exec.Shutdown(signal, timeout); err != nil { + if handle.pluginClient.Exited() { + return nil + } + return fmt.Errorf("executor Shutdown failed: %v", err) + } + + return nil +} + +// DestroyTask cleans up and removes a task that has terminated. +func (d *HelloDriverPlugin) DestroyTask(taskID string, force bool) error { + handle, ok := d.tasks.Get(taskID) + if !ok { + return drivers.ErrTaskNotFound + } + + if handle.IsRunning() && !force { + return errors.New("cannot destroy running task") + } + + // TODO: implement driver specific logic to destroy a complete task. + // + // Destroying a task includes removing any resources used by task and any + // local references in the plugin. If force is set to true the task should + // be destroyed even if it's currently running. + // + // In the example below we use the executor to force shutdown the task + // (timeout equals 0). + if !handle.pluginClient.Exited() { + if err := handle.exec.Shutdown("", 0); err != nil { + handle.logger.Error("destroying executor failed", "err", err) + } + + handle.pluginClient.Kill() + } + + d.tasks.Delete(taskID) + return nil +} + +// InspectTask returns detailed status information for the referenced taskID. +func (d *HelloDriverPlugin) InspectTask(taskID string) (*drivers.TaskStatus, error) { + handle, ok := d.tasks.Get(taskID) + if !ok { + return nil, drivers.ErrTaskNotFound + } + + return handle.TaskStatus(), nil +} + +// TaskStats returns a channel which the driver should send stats to at the given interval. +func (d *HelloDriverPlugin) TaskStats(ctx context.Context, taskID string, interval time.Duration) (<-chan *drivers.TaskResourceUsage, error) { + handle, ok := d.tasks.Get(taskID) + if !ok { + return nil, drivers.ErrTaskNotFound + } + + // TODO: implement driver specific logic to send task stats. + // + // This function returns a channel that Nomad will use to listen for task + // stats (e.g., CPU and memory usage) in a given interval. It should send + // stats until the context is canceled or the task stops running. + // + // In the example below we use the Stats function provided by the executor, + // but you can build a set of functions similar to the fingerprint process. + return handle.exec.Stats(ctx, interval) +} + +// TaskEvents returns a channel that the plugin can use to emit task related events. +func (d *HelloDriverPlugin) TaskEvents(ctx context.Context) (<-chan *drivers.TaskEvent, error) { + return d.eventer.TaskEvents(ctx) +} + +// SignalTask forwards a signal to a task. +// This is an optional capability. +func (d *HelloDriverPlugin) SignalTask(taskID string, signal string) error { + handle, ok := d.tasks.Get(taskID) + if !ok { + return drivers.ErrTaskNotFound + } + + // TODO: implement driver specific signal handling logic. + // + // The given signal must be forwarded to the target taskID. If this plugin + // doesn't support receiving signals (capability SendSignals is set to + // false) you can just return nil. + sig := os.Interrupt + if s, ok := signals.SignalLookup[signal]; ok { + sig = s + } else { + d.logger.Warn("unknown signal to send to task, using SIGINT instead", "signal", signal, "task_id", handle.taskConfig.ID) + + } + return handle.exec.Signal(sig) +} + +// ExecTask returns the result of executing the given command inside a task. +// This is an optional capability. +func (d *HelloDriverPlugin) ExecTask(taskID string, cmd []string, timeout time.Duration) (*drivers.ExecTaskResult, error) { + // TODO: implement driver specific logic to execute commands in a task. + return nil, errors.New("This driver does not support exec") +} |