TaskCluster Client

A taskcluster client library for node.js.

This client library is generated from the auto-generated API reference. You can create a Client class from a JSON reference object at runtime using taskcluster.createClient(reference). But there is also a set of builtin references from which Client classes are already constructed.

Calling API End-Points

To invoke an API end-point instantiate a taskcluster Client class, these are classes can be created from a JSON reference object, but a number of them are also built-in to this library. In the following example we instantiate an instance of the Queue Client class and use to to create a task.

var taskcluster = require('taskcluster-client');

// Instantiate the Queue Client class
var queue = new taskcluster.Queue({
  credentials: {
    clientId:     '...',
    accessToken:  '...'
  }
});

// Create task using the queue client
var taskId = '...';
queue.createTask(taskId, task).then(function(result) {
  // status is a task status structure
  console.log(result.status);
});

The payload parameter is always a JSON object as documented by the REST API documentation. The methods always returns a promise for the response JSON object as documented in the REST API documentation.

Listening for Events

Many TaskCluster components publishes messages about current events over AMQP. The JSON reference object also contains meta-data about declared AMQP topic exchanges and their routing key construction. This is designed to make it easy to construct routing key patterns and parse routing keys from incoming messages.

The following example create a listener and instantiate an instance of the Client class QueueEvents which we use to find the exchange and create a routing pattern to listen for completion of a specific task. The taskCompleted method will construct a routing key pattern by using * or # for missing entries, pending on whether or not they are single word or multi-key entries.

var taskcluster = require('taskcluster-client');

// Create a listener (this creates a queue on AMQP)
var listener = new taskcluster.Listener({
  connectionString:   'amqp://...'
});

// Instantiate the QueueEvents Client class
var queueEvents = new taskcluster.QueueEvents();

// Bind to task-completed events from queue that matches routing key pattern:
//   'primary.<myTaskId>.*.*.*.*.*.#'
listener.bind(queueEvents.taskCompleted({taskId: '<myTaskId>'}));

// Listen for messages
listener.on('message', function(message) {
  message.exchange        // Exchange from which message came
  message.payload         // Documented on docs.taskcluster.net
  message.routingKey      // Message routing key in string format
  message.routing.taskId  // Element from parsed routing key
  message.routing.runId   // ...
  message.redelivered     // True, if message has been nack'ed and requeued
  return new Promise(...);
});

// Listen and consume events:
listener.resume().then(function() {
  // Now listening
});

To bind to a custom routing-key like the task-specific routes that messages from the queue is CC'ed to, just provide the desired routing key to the method for exchange. See example below.

var RawRoutingPattern = 'route.task.specific.routing.key';
listener.bind(queueEvents.taskCompleted(RawRoutingPattern);

Advanced Listening

For advanced queue usage the connect method can be used to create and bind the queue and return an associated amqplib channel:

var taskcluster = require('taskcluster-client');

// Create a listener (this creates a queue on AMQP)
var listener = new taskcluster.Listener({
  connectionString:   'amqp://...'
});

// See: http://www.squaremobius.net/amqp.node/doc/channel_api.html
var channel = listener.connect().then(function(channel) {
  return channel.consume(function(msg) {
    channel.ack(msg);
  });
});

The listener creates a AMQP queue, on the server side and subscribes to messages on the queue. It's possible to use named queues, see details below. For details on routing key entries refer to documentation on docs.taskcluster.net.

Remark, API end-points and AMQP exchanges are typically documented in separate reference files. For this reason they also have separate Client classes, even if they are from the same component.

Documentation

The set of API entries listed below is generated from the builtin references. Detailed documentation with description, payload and result format details is available on docs.taskcluster.net.

On the documentation site entries often have a signature, you'll find that it matches the signatures below. Notice that all the methods returns a promise. A method with : void also returns a promise, that either resolves without giving a value or rejects with an error.

Methods in taskcluster.Auth

// Create Auth client instance with default baseUrl:
//  - https://auth.taskcluster.net/v1
var auth = new taskcluster.Auth(options);

• auth.inspect(clientId) : result
• auth.getCredentials(clientId) : result

Methods in taskcluster.Queue

// Create Queue client instance with default baseUrl:
//  - https://queue.taskcluster.net/v1
var queue = new taskcluster.Queue(options);

• queue.createTask(taskId, payload) : result
• queue.getTask(taskId) : result
• queue.defineTask(taskId, payload) : result
• queue.scheduleTask(taskId) : result
• queue.status(taskId) : result
• queue.claimTask(taskId, runId, payload) : result
• queue.reclaimTask(taskId, runId) : result
• queue.claimWork(provisionerId, workerType, payload) : result
• queue.reportCompleted(taskId, runId, payload) : result
• queue.rerunTask(taskId) : result
• queue.createArtifact(taskId, runId, name, payload) : result
• queue.getArtifact(taskId, runId, name) : void
• queue.getLastestArtifact(taskId, name) : void
• queue.listArtifacts(taskId, runId) : result
• queue.listLatestArtifacts(taskId) : result
• queue.getPendingTasks(provisionerId) : void
• queue.getAMQPConnectionString() : result
• queue.ping() : void

Methods in taskcluster.Scheduler

// Create Scheduler client instance with default baseUrl:
//  - https://scheduler.taskcluster.net/v1
var scheduler = new taskcluster.Scheduler(options);

• scheduler.createTaskGraph(taskGraphId, payload) : result
• scheduler.extendTaskGraph(taskGraphId, payload) : result
• scheduler.status(taskGraphId) : result
• scheduler.info(taskGraphId) : result
• scheduler.inspect(taskGraphId) : result
• scheduler.ping() : void

Exchanges in taskcluster.QueueEvents

// Create QueueEvents client instance with default exchangePrefix:
//  - queue/v1/
var queueEvents = new taskcluster.QueueEvents(options);

• queueEvents.taskDefined(routingKeyPattern) : binding-info
• queueEvents.taskPending(routingKeyPattern) : binding-info
• queueEvents.taskRunning(routingKeyPattern) : binding-info
• queueEvents.artifactCreated(routingKeyPattern) : binding-info
• queueEvents.taskCompleted(routingKeyPattern) : binding-info
• queueEvents.taskFailed(routingKeyPattern) : binding-info

Exchanges in taskcluster.SchedulerEvents

// Create SchedulerEvents client instance with default exchangePrefix:
//  - scheduler/v1/
var schedulerEvents = new taskcluster.SchedulerEvents(options);

• schedulerEvents.taskGraphRunning(routingKeyPattern) : binding-info
• schedulerEvents.taskGraphExtended(routingKeyPattern) : binding-info
• schedulerEvents.taskGraphBlocked(routingKeyPattern) : binding-info
• schedulerEvents.taskGraphFinished(routingKeyPattern) : binding-info

Construct Urls

You can build a url for any request, but this feature is mostly useful for request that doesn't require any authentication. If you need authentication take a look at the section on building signed urls, which is possible for all GET requests. To construct a url for a request use the buildUrl method, as illustrated in the following example:

// Create queue instance
var queue = new taskcluster.Queue(...);

// Build url to get a specific task
var url = queue.buildUrl(
  queue.getTask,    // Method to build url for.
  taskId            // First parameter for the method, in this case taskId
);

Please, note that the payload parameter cannot be encoded in urls. And must be sent when using a constructed urls. Again, this is not a problem as most methods that takes a payload also requires authentication.

Construct Signed Urls

It's possible to build both signed urls for all GET requests. A signed url contains a query-string parameter called bewit, this parameter holds expiration time, signature and scope restrictions (if applied). The signature covers the following parameters:

• Expiration time,
• Url and query-string, and
• scope restrictions (if applied)

These signed urls is very convenient if you want to grant somebody access to specific resource without proxying the request or sharing your credentials. For example it's fairly safe to provide someone with a signed url for a specific artifact that is protected by a scope. See example below.

// Create queue instance
var queue = new taskcluster.Queue(...);

// Build signed url
var signedUrl = queue.buildSignedUrl(
  queue.getArtifactFromRun,   // method to build signed url for.
  taskId,                     // TaskId parameter
  runId,                      // RunId parameter
  artifactName,               // Artifact name parameter
  {
    expiration:     60 * 10   // Expiration time in seconds
});

Please, note that the payload parameter cannot be encoded in the signed url and must be sent as request payload. This should work fine, just remember that it's only possible to make signed urls for GET requests, which in most cases don't take a payload.

Also please consider using a relatively limited expiration time, as it's not possible to retract a signed url without revoking your credentials. For more technical details on signed urls, see bewit urls in hawk.

Create Client Class Dynamically

You can create a Client class from a reference JSON object as illustrated below:

var reference = {...}; // JSON from references.taskcluster.net/...

// Create Client class
var MyClient = taskcluster.createClient(reference);

// Instantiate an instance of MyClient
var myClient = new MyClient(options);

// Make a request with a method on myClient
myClient.myMethod(arg1, arg2, payload).then(function(result) {
  // ...
});

Configuration of API Invocations

There is a number of configuration options for Client which affects invocation of API end-points. These are useful if using a non-default server, for example when setting up a staging area or testing locally.

Configuring API BaseUrls

If you use the builtin API Client classes documented above you can configure the baseUrl when creating an instance of the client. As illustrated below:

var auth = new taskcluster.Auth({
  credentials:  {...},
  baseUrl:      "http://localhost:4040" // Useful for development and testing
});

Configuring Credentials

When creating an instance of a Client class the credentials can be provided in options. For example:

var auth = new taskcluster.Auth({
  credentials: {
    clientId:     '...',
    accessToken:  '...'
  }
});

You can also configure default options globally using taskcluster.config(options), as follows:

// Configure default options
taskcluster.config({
  credentials: {
    clientId:     '...',
    accessToken:  '...'
  }
});

// No credentials needed here
var auth = new taskcluster.Auth();

If the clientId and accessToken are left empty we also check the TASKCLUSTER_CLIENT_ID and TASKCLUSTER_ACCESS_TOKEN environment variables to use as defaults (similar to how AWS, Azure, etc. handle authentication).

Restricting Authorized Scopes

If you wish to perform requests on behalf of a third-party that has small set of scopes than you do. You can specify which scopes your request should be allowed to use, in the key authorizedScopes. This is useful when the scheduler performs a request on behalf of a task-graph, or when authentication takes place in a trusted proxy. See example below:

// Create a Queue Client class can only define tasks for a specific workerType
var queue = new taskcluster.Queue({
  // Credentials that can define tasks for any provisioner and workerType.
  credentials: {
    clientId:       '...',
    accessToken:    '...'
  },
  // Restricting this instance of the Queue client to only one scope
  authorizedScopes: ['queue:post:define-task/my-provisioner/my-worker-type']
});

// This request will only be successful, if the task posted is aimed at
// "my-worker-type" under "my-provisioner".
queue.defineTask(taskId taskDefinition).then(function(result) {
  // ...
});

Configuration of Exchange Bindings

When a taskcluster Client class is instantiated the option exchangePrefix may be given. This will replace the default exchangePrefix. This can be useful if deploying a staging area or similar. See example below:

// Instantiate the QueueEvents Client class
var queueEvents = new taskcluster.QueueEvents({
  exchangePrefix:     'staging-queue/v1/'
});

// This listener will now bind to: staging-queue/v1/task-completed
listener.bind(queueEvents.taskCompleted({taskId: '<myTaskId>'}));

Using the Listener

TaskCluster relies on AMQP for exchanges of messages. You'll need an AMQP connection string for using the taskcluster AMQP listener. An outline of how to create an instance and use is given below. Note, you must call resume() before message starts arriving.

var listener = new taskcluster.Listener({
  prefetch:           5,            // Number of tasks to process in parallel
  connectionString:   'amqp://...', // AMQP connection string
  // If no queue name is given, the queue is:
  //    exclusive, autodeleted and non-durable
  // If a queue name is given, the queue is:
  //    durable, not auto-deleted and non-exclusive
  queueName:          'my-queue',   // Queue name, undefined if none
  maxLength:          0,            // Max allowed queue size
});

listener.connect().then(...);       // Setup listener and bind queue
listener.resume().then(...);        // Start getting new messages
listener.pause().then(...);         // Pause retrieval of new messages
listener.deleteQueue();             // Delete named queue and disconnect
listener.close();                   // Disconnect from AMQP

Using Connection, instead of giving a connectionString it is also possible to give the Listener the key connection which must then be a taskcluster.Connection object. Using a Connection object it's possible to have multiple listeners using the same AMQP TCP connection, which is the recommended way of using AMQP. Notice, that the Connection will not be closed with the Listeners, so you must close() it manually.

var connection = new taskcluster.Connection({
  connectionString:   'amqp://...', // AMQP connection string
});

// Create listener
var listener = new taskcluster.Listener({
  connection:         connection,   // AMQP connection object
});


connection.close();                 // Disconnect from AMQP

Using taskcluster-client in a Browser

Running the script utils/browserify.js will generate taskcluster-client.js using browserify. This does not contain any listener, but all the API logic and references is present. To get AMQP events in the browser use events.taskcluster.net.

Updating Builtin APIs

When releasing a new version of the taskcluster-client library, we should always update the builtin references using utils/update-apis.js this maintenance script can be used to list, show, add, remove and update builtin API definitions.

When apis.json is updated, please run utils/generate-docs.js to update the documentation in this file.

##License The taskcluster client library is released on MPL 2.0.