Add Driver.Prestart method #2054

schmichael · 2016-12-02T19:09:25Z

The Driver.Prestart method currently does very little but lays the foundation for where lifecycle plugins can interleave execution after task environment setup but before the task starts.

Currently Prestart does two things:

Any driver specific task environment building
Download Docker images

This change also attaches a TaskEvent emitter to Drivers, so they can emit events during task initialization.

The Driver.Prestart method currently does very little but lays the foundation for where lifecycle plugins can interleave execution _after_ task environment setup but _before_ the task starts. Currently Prestart does two things: * Any driver specific task environment building * Download Docker images This change also attaches a TaskEvent emitter to Drivers, so they can emit events during task initialization.

dadgar · 2016-12-20T00:41:21Z

client/driver/exec.go

@@ -92,6 +92,13 @@ func (d *ExecDriver) Periodic() (bool, time.Duration) {
 	return true, 15 * time.Second
 }

+func (d *ExecDriver) Prestart(execctx *ExecContext, task *structs.Task) error {
+	// Set the host environment variables.
+	filter := strings.Split(d.config.ReadDefault("env.blacklist", config.DefaultEnvBlacklist), ",")


This should be done in all driver Prestarts. It was missed in some of the newer drivers. We should create a common Prestart method that all drivers can call

Should I just move it into TaskRunner instead?

I (indirectly) added it to TaskRunner by putting it in the GetTaskEnv factory: aaa70ab

dadgar · 2016-12-20T00:43:23Z

client/driver/docker.go

 	// We don't need to start the container if the container is already running
 	// since we don't create containers which are already present on the host
 	// and are running
 	if !container.State.Running {
 		// Start the container
-		err := d.startContainer(container)
-		if err != nil {
+		if err := client.StartContainer(container.ID, container.HostConfig); err != nil {


Why did you change from d.startContainer?

Yikes. No clue. Thanks for catching this. Fixed.

dadgar · 2016-12-20T00:47:36Z

api/tasks.go

+	VaultError            string
+	TaskSignalReason      string
+	TaskSignal            string
+	InitializationMessage string


Change to DriverMsg as the emitEvent function can be used generically by the driver?

Any thoughts on what I should change the TaskInitializing const to? All of the other consts are verbs, but I don't think it'd be confusing to just have a "Driver" message type.

"Driver" is fine with me

dadgar · 2016-12-20T01:15:22Z

client/driver/docker.go

@@ -339,46 +343,57 @@ func (d *DockerDriver) Abilities() DriverAbilities {
 	}
 }

-func (d *DockerDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
+func (d *DockerDriver) Prestart(ctx *ExecContext, task *structs.Task) error {


Can you emit a message for when it downloads an image?

Can't believe I missed that in this PR! Added (inside the createImage method so it's not emitted if the image already exists).

dadgar · 2016-12-20T01:16:25Z

client/driver/docker.go

@@ -91,6 +91,10 @@ const (

 type DockerDriver struct {
 	DriverContext
+
+	imageID      string
+	waitClient   *docker.Client


You don't have to pass this as it is a shared variable that is initialized once per client

Tangent: Hm, should I be using the waitClient for image downloading?

dadgar · 2016-12-20T01:17:01Z

client/driver/docker.go

 	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)
+		return fmt.Errorf("Could not find task directory for task: %v", d.DriverContext.taskName)


taskDir is a variable in the task_runner now. Pass it through the context?

That's in the next PR

dadgar · 2016-12-20T01:43:08Z

client/driver/lxc.go

@@ -168,6 +168,10 @@ func (d *LxcDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool, e
 	return true, nil
 }

+func (d *LxcDriver) Prestart(ctx *ExecContext, task *structs.Task) error {
+	return nil


Shouldn't we be setting the env vars here since the paths will be rooted in the container?

Not sure I follow. TaskEnv is built in TaskRunner.Run before the driver is created and passed into the NewDriver factory func via DriverContext, so it's already built and available at this point.

dadgar · 2016-12-20T19:43:20Z

client/driver/docker.go

@@ -950,6 +950,7 @@ func (d *DockerDriver) pullImage(driverConfig *DockerDriverConfig, client *docke
 		}
 	}

+	d.emitEvent("Downloading image")


d.emitEventfmt.Sprintf(`Downloading image "%s:%s"`, repo, tag))

Good call; fixed.

dadgar · 2016-12-21T00:08:50Z

client/driver/java.go

@@ -163,16 +163,19 @@ func (d *JavaDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool,
 	return true, nil
 }

+func (d *JavaDriver) Prestart(ctx *ExecContext, task *structs.Task) error {
+	// Set the host environment variables.
+	filter := strings.Split(d.config.ReadDefault("env.blacklist", config.DefaultEnvBlacklist), ",")


dadgar · 2016-12-21T00:09:14Z

client/driver/raw_exec.go

@@ -107,6 +107,13 @@ func (d *RawExecDriver) Fingerprint(cfg *config.Config, node *structs.Node) (boo
 	return false, nil
 }

+func (d *RawExecDriver) Prestart(ctx *ExecContext, task *structs.Task) error {
+	// Set the host environment variables.
+	filter := strings.Split(d.config.ReadDefault("env.blacklist", config.DefaultEnvBlacklist), ",")


github-actions · 2023-04-12T02:10:42Z

I'm going to lock this pull request because it has been closed for 120 days ⏳. This helps our maintainers find and focus on the active contributions.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.

dadgar requested changes Dec 20, 2016

View reviewed changes

Emit "Downloading image" event

50934da

dadgar reviewed Dec 20, 2016

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schmichael added 7 commits December 20, 2016 11:51

Rename InitializationMessage to DriverMessage

750d597

Use startContainer wrapper

bbcc27e

Fix formatting of downloading image message

6702813

Append host env vars on every task env

aaa70ab

Remove unneeded waitClient field

5ad7eea

lxc: Set image local env vars

630812b

Fix tests broken by TaskEnv change

decee19

dadgar reviewed Dec 21, 2016

View reviewed changes

dadgar approved these changes Dec 21, 2016

View reviewed changes

Remove unneeded env building

904543e

schmichael merged commit fccf115 into master Dec 21, 2016

schmichael deleted the f-prestart branch December 21, 2016 00:19

schmichael mentioned this pull request Jan 18, 2017

Image based drivers should not include host env vars #2211

Closed

schmichael mentioned this pull request Jan 27, 2017

Emit download begin/finished state event for docker images #2246

Closed

github-actions bot locked as resolved and limited conversation to collaborators Apr 12, 2023

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Add Driver.Prestart method #2054

Add Driver.Prestart method #2054

schmichael commented Dec 2, 2016

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Add Driver.Prestart method #2054

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schmichael commented Dec 2, 2016

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schmichael Dec 20, 2016 • edited Loading

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