Job retries and error handling in Ruby on Rails - Mini Project: Build & Apply

Job retries and error handling

📖 Scenario: You are building a background job in a Rails application that processes user data. Sometimes the job might fail due to temporary issues like network errors. You want to add retry logic and error handling to make the job more reliable.

🎯 Goal: Create a Rails Active Job class that retries up to 3 times on failure and logs errors when retries are exhausted.

📋 What You'll Learn

Create a job class named UserDataJob

Add a retry configuration to retry the job 3 times

Implement error handling to log a message when retries are exhausted

Use the perform method to simulate job work

💡 Why This Matters

🌍 Real World

Background jobs often fail due to temporary issues like network problems. Adding retries and error handling makes jobs more reliable and improves user experience.

💼 Career

Understanding job retries and error handling is essential for backend developers working with Rails to build robust and fault-tolerant applications.

1

Create the job class

Create a Rails job class called UserDataJob that inherits from ApplicationJob. Define an empty perform method that takes a parameter called user_id.

Ruby on Rails

class UserDataJob < ApplicationJob
  # Define perform method with user_id parameter
  def perform(user_id)
    # Your code here
  end
end

Need a hint?

Use class UserDataJob < ApplicationJob and define def perform(user_id).

2

Add retry configuration

Add a retry configuration to UserDataJob to retry the job 3 times on failure using retry_on with StandardError.

Ruby on Rails

class UserDataJob < ApplicationJob
  retry_on StandardError, attempts: 3

  def perform(user_id)
    # Your code here
  end
end

Need a hint?

Use retry_on StandardError, attempts: 3 inside the job class.

3

Implement job logic with error simulation

Inside the perform method, simulate job work by raising a StandardError with the message 'Temporary failure' to test retries.

Ruby on Rails

class UserDataJob < ApplicationJob
  retry_on StandardError, attempts: 3

  def perform(user_id)
    # Simulate a temporary failure
    # Your code here
  end
end

Need a hint?

Use raise StandardError, 'Temporary failure' inside perform.

4

Add error handling after retries exhausted

Add an discard_on handler for StandardError that logs the message 'Job failed after retries' using Rails.logger.error.

Ruby on Rails

class UserDataJob < ApplicationJob
  retry_on StandardError, attempts: 3
  # Add discard_on handler below

  def perform(user_id)
    raise StandardError, 'Temporary failure'
  end
end

Need a hint?

Use discard_on StandardError do |job, error| and inside log with Rails.logger.error.