Enqueue functions with Cloud Tasks

Task queue functions take advantage of Google Cloud Tasks to help your app run time-consuming, resource-intensive, or bandwidth-limited tasks asynchronously, outside your main application flow.

For example, imagine that you want to create backups of a large set of image files that are currently hosted on an API with a rate limit. In order to be a responsible consumer of that API, you need to respect their rate limits. Plus, this kind of long-running job could be vulnerable to failure due to timeouts and memory limits.

To mitigate this complexity, you can write a task queue function that sets basic task options like scheduleTime , and dispatchDeadline , and then hands the function off to a queue in Cloud Tasks . The Cloud Tasks environment is designed specifically to ensure effective congestion control and retry policies for these kinds of operations.

The Firebase SDK for Cloud Functions for Firebase v3.20.1 and higher interoperates with Firebase Admin SDK v10.2.0 and higher to support task queue functions.

Using task queue functions with Firebase can result in charges for Cloud Tasks processing. See Cloud Tasks pricing for more information.

Create task queue functions

To use task queue functions, follow this workflow:

1. Write a task queue function using the Firebase SDK for Cloud Functions .
2. Test your function by triggering it with an HTTP request.
3. Deploy your function with the Firebase CLI. When deploying your task queue function for the first time, the CLI will create a task queue in Cloud Tasks with options (rate limiting and retry) specified in your source code.
4. Add tasks to the newly created task queue, passing along parameters to set up an execution schedule if needed. You can achieve this by writing the code using the Admin SDK and deploying it to Cloud Functions for Firebase .

Write task queue functions

Code samples in this section are based on an app that sets up a service that backs up all images from NASA's Astronomy Picture of the Day . To get started, import the required modules:

  // Dependencies for task queue functions. 
 const 
  
 { 
 onTaskDispatched 
 } 
  
 = 
  
 require 
 ( 
 "firebase-functions/tasks" 
 ); 
 const 
  
 { 
 onRequest 
 , 
  
 HttpsError 
 } 
  
 = 
  
 require 
 ( 
 "firebase-functions/https" 
 ); 
 const 
  
 { 
 getFunctions 
 } 
  
 = 
  
 require 
 ( 
 "firebase-admin/functions" 
 ); 
 const 
  
 { 
 logger 
 } 
  
 = 
  
 require 
 ( 
 "firebase-functions" 
 ); 
 // Dependencies for image backup. 
 const 
  
 path 
  
 = 
  
 require 
 ( 
 "path" 
 ); 
 const 
  
 { 
 initializeApp 
 } 
  
 = 
  
 require 
 ( 
 "firebase-admin/app" 
 ); 
 const 
  
 { 
 getStorage 
 } 
  
 = 
  
 require 
 ( 
 "firebase-admin/storage" 
 ); 
 const 
  
 { 
 GoogleAuth 
 } 
  
 = 
  
 require 
 ( 
 "google-auth-library" 
 ); 
 
  index 
 . 
 js 
 
 
 

  # Dependencies for task queue functions. 
 from 
  
 google.cloud 
  
 import 
 tasks_v2 
 import 
  
 requests 
 from 
  
 firebase_functions.options 
  
 import 
 RetryConfig 
 , 
 RateLimits 
 , 
 SupportedRegion 
 # Dependencies for image backup. 
 from 
  
 datetime 
  
 import 
 datetime 
 , 
 timedelta 
 import 
  
 json 
 import 
  
 pathlib 
 from 
  
 urllib.parse 
  
 import 
 urlparse 
 from 
  
 firebase_admin 
  
 import 
 initialize_app 
 , 
 storage 
 , 
 functions 
 from 
  
 firebase_functions 
  
 import 
 https_fn 
 , 
 tasks_fn 
 , 
 params 
 import 
  
 google.auth 
 from 
  
 google.auth.transport.requests 
  
 import 
 AuthorizedSession 
 main 
 
 
 . 
 py