Need private packages and team management tools?Check out npm Orgs. »


21.0.0 • Public • Published

Taskcluster Client

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. The following example instantiates an instance of the Queue Client class, showing all available options, and uses it to to create a task. Note that only the rootUrl option is required.

var taskcluster = require('taskcluster-client');
// Instantiate the Queue Client class
var queue = new taskcluster.Queue({
  // rootUrl for this Taskcluster instance (required)
  rootUrl: '',
  // Taskcluster credentials (required only for API methods that require scopes)
  credentials: {
    clientId:     '...',
    accessToken:  '...',
    // Certificate must also be provided if using temporary credentials,
    // this can be either a JSON object or a JSON string.
    certificate:  {...}   // Only applicable for temporary credentials
  // timeout for _each_ invidual http request
  timeout: 30 * 1000,
  // maximum number of retries for transient errors (default 5)
  retries: 5,
  // Multiplier for computation of retry delay: 2 ^ retry * delayFactor,
  // 100 ms is solid for servers, and 500ms - 1s is suitable for background
  // processes
  delayFactor: 100,
  // Randomization factor added as.
  // delay = delay * random([1 - randomizationFactor; 1 + randomizationFactor])
  randomizationFactor: 0.25,
  // Maximum retry delay (defaults to 30 seconds)
  maxDelay: 30 * 1000,
  // By default we share a global HTTP agent. If you specify one, your instance
  // will have its own agent with the given options...
  agent: undefined,
  // Fake methods, for testing
  fake: null,
// Create task using the queue client
var taskId = '...';
queue.createTask(taskId, payload).then(function(result) {
  // status is a task status structure

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.

If you need to create a client similar to a existing client, but with some options changed, use client.use(options):

  .use({authorizedScopes: [..]})

This replaces any given options with new values.

Listening for Events

NOTE PulseListener is no longer included in taskcluster-client; instead, use PulseConsumer from taskcluster-lib-pulse.

However, this library helpfully includes bindings for exchanges declared by various Taskcluster services. To use these with taskcluster-lib-pulse, create an ..Events instance, call the apprporiate methods on it to construct a binding, and pass that to pulse.consume:

var taskcluster = require('taskcluster-client');
// Instantiate the QueueEvents Client class
var queueEvents = new taskcluster.QueueEvents({rootUrl: ..});
let pc = await pulse.consume({
  bindings: [
    // Bind to task-completed events from queue that matches routing key pattern:
    //   'primary.<myTaskId>.*.*.*.*.*.#'
    queueEvents.taskCompleted({taskId: myTaskId});
  ], ..);


The set of API entries is generated from the built-in references. Detailed documentation with description, payload and result format details is available in the reference section of the Taskcluster documentation.

Providing Options

Some API end-points may take query-string, this is indicated in the signature above as [options]. These options are always optional, commonly used for continuation tokens when paging a list. For list of supported options you should consult API documentation.

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.

Generating Temporary Credentials

If you have non-temporary taskcluster credentials you can generate a set of temporary credentials as follows. Notice that the credentials cannot last more than 31 days, and you can only revoke them by revoking the credentials that was used to issue them (this takes up to one hour).

var credentials = taskcluster.createTemporaryCredentials({
  // Name of temporary credential (optional)
  clientId:           '...',
  // Validity of temporary credentials starts here
  start:              new Date(),
  // Expiration of temporary credentials
  expiry:             new Date(new Date().getTime() + 5 * 60 * 1000),
  // Scopes to grant the temporary credentials
  scopes:             ['ScopeA', 'ScopeB', ...]
  credentials: {      // Non-temporary taskcluster credentials
    clientId:         '...'
    accessToken:      '...'

You cannot use temporary credentials to issue new temporary credentials. You must have auth:create-client:<name> to create a named temporary credential, but unnamed temporary credentials can be created regardless of your scopes.

Create Client Class Dynamically

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

var reference = {...}; // JSON from
// 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 Root URL and Credentials

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

var auth = new taskcluster.Auth({
  rootUrl:      ""

You may also provide credentials. For example:

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

If the clientId and accessToken are not given, no credentials will be used.

You can set either or both of these values as global config options as below:

// Configure default options
  rootUrl: "",
  credentials: {
    clientId:     '...',
    accessToken:  '...'
// No rootUrl needed here
var auth = new taskcluster.Auth();

You can read credentials and rootUrl from the standard TASKCLUSTER_… environment variables with taskcluster.fromEnvVars():

var auth = new taskcluster.Auth({
// or (to get behavior like that in versions 11.0.0 and earlier):

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) {
  // ...

Relative Date-time Utilities

A lot of taskcluster APIs requires ISO 8601 time stamps offset into the future as way of providing expiration, deadlines, etc. These can be easily created using new Date().toJSON(), however, it can be rather error prone and tedious to offset Date objects into the future. Therefore this library comes with two utility functions for this purposes.

var dateObject = taskcluster.fromNow("2 days 3 hours 1 minute");
var dateString = taskcluster.fromNowJSON("2 days 3 hours 1 minute");
assert(dateObject.toJSON() === dateString);
// dateObject = now() + 2 days 2 hours and 1 minute
assert(new Date().getTime() < dateObject.getTime());

By default it will offset the date time into the future, if the offset strings are prefixed minus (-) the date object will be offset into the past. This is useful in some corner cases.

var dateObject = taskcluster.fromNow("- 1 year 2 months 3 weeks 5 seconds");
// dateObject = now() - 1 year, 2 months, 3 weeks and 5 seconds
assert(new Date().getTime() > dateObject.getTime());

The offset string is ignorant of whitespace and case insensitive. It may also optionally be prefixed plus + (if not prefixed minus), any + prefix will be ignored. However, entries in the offset string must be given in order from high to low, ie. 2 years 1 day. Additionally, various shorthands may be employed, as illustrated below.

  years,    year,   yr,   y
  months,   month,  mo
  weeks,    week,   wk,   w
  days,     day,          d
  hours,    hour,   hr,   h
  minutes,  minute, min
  seconds,  second, sec,  s

The fromNow method may also be given a date to be relative to as a second argument. This is useful if offset the task expiration relative to the the task deadline or doing something similar.

var dateObject1 = taskcluster.fromNow("2 days 3 hours");
// dateObject1  = now() + 2 days and 3 hours
var dateObject2 = taskcluster.fromNow("1 year", dateObject1);
// dateObject2  = now() + 1 year, 2 days and 3 hours

Handling Credentials

Your users may find the options for Taskcluster credentials overwhelming. You can help by interpreting the credentials for them.

The credentialInformation(rootUrl, credentials) function returns a promise with information about the given credentials:

   clientId: "..",      // name of the credential
   type: "..",          // type of credential, e.g., "temporary"
   active: "..",        // active (valid, not disabled, etc.)
   start: "..",         // validity start time (if applicable)
   expiry: "..",        // validity end time (if applicable)
   scopes: ["..."],     // associated scopes (if available)

The resulting information should only be used for presentation purposes, and never for access control. This function may fail unexpectedly with invalid credentials, and performs no cryptographic checks. It is acceptable to use the scopes result to determine whether to display UI elements associated with a particular scope, as long as the underlying API performs more reliable authorization checks.

Generating slugids

In node you can rely on the slugid module to generate slugids, but we already need it in taskcluster-client and expose the preferred slugid generation function as taskcluster.slugid().

var taskcluster = require('taskcluster-client');
// Generate new taskId
var taskId = taskcluster.slugid();

The generates nice random slugids, refer to slugid module for further details.

Fake API Methods

In testing, it is useful to be able to "fake out" client methods so that they do not try to communicate with an actual, external service. The normal client argument checking still takes place, and a function of your design will be called instead of calling the external service.

This is set up when constructing the client. Typically, this occurs in a taskcluster-lib-loader entry.

setup(function () {
  // inject the dependency with a stickyLoader from taskcluster-lib-testing
  helper.load.inject('secrets', new taskcluster.Secrets({
    fake: {
      get: (name) => 'my-hardcoded-secret',
test('test the thing', async function() {
  // Get secrets from injection above
  let secrets = await helper.load('secrets');
  // Do something with the secrets object
  let s = await secrets.get('thing-to-read');
  // Make assertions over recorded calls
    name: 'thing-to-read',
  try {
    await secrets.remove('...', {}); // throws and error because we didn't fake it
  } catch (err) {
    // pass


The taskcluster client library is released on MPL 2.0.




npm i taskcluster-client

Downloadsweekly downloads








last publish


  • avatar
  • avatar
  • avatar
  • avatar
  • avatar
  • avatar
  • avatar
  • avatar
Report a vulnerability