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Azure_WebJobs

WebJob and background processing.

1. Why WebJobs?

🤔 Why Use Azure WebJobs?

Azure WebJobs provide an easy way to run background tasks or scripts in the context of an Azure App Service (Web App). They simplify running scheduled or continuous jobs without managing separate infrastructure.

Key Benefits of WebJobs

  • Integrated with App Services: Runs inside the same environment as your web app, sharing resources and scaling.

  • Simple to Deploy: Deploy code or scripts alongside your web app without separate VM or service.

  • Multiple Execution Modes:

    - Continuous: Runs continuously in the background.
- Triggered: Runs on demand or scheduled (using Azure Scheduler or TimerTriggers).

  • Supports Various Languages: Run .NET, PowerShell, Python, Node.js, and more.

  • Cost-Effective: No need for separate VMs or services for background processing.
  • Easy Management: Use Azure Portal or CLI to monitor, start, stop WebJobs.
  • Ideal for:
     - Processing queues or blobs.
 - Scheduled maintenance tasks.
 - Data import/export.
 - Any background processing tasks related to your web app.

When to Use WebJobs?

  • When you want to add background or scheduled jobs without extra infrastructure.
  • When your background task is tightly coupled with your web app lifecycle.
  • For lightweight to moderate background processing needs.

Alternatives

  • For more complex or independent background processing, consider:

  • Azure Functions (serverless)

  • Azure Logic Apps
  • Azure Service Bus with worker roles or microservices

2. Types of Webjobs (Triggered, Continuos.)

🌀 Types of Azure WebJobs

Azure WebJobs run background tasks in an Azure App Service environment and come in two main types:

1. Continuous WebJobs

  • Runs: Continuously in the background as long as the App Service is running.

  • Use Cases: Real-time processing, long-running tasks, listening to queues or events.

  • Behavior:

    - Starts automatically when the App Service starts.
- Runs in an infinite loop or waits for events/messages.

  • Example: Monitoring a queue for incoming messages to process.

2. Triggered WebJobs

  • Runs: On-demand or on a schedule.

  • Use Cases: Periodic tasks, batch jobs, maintenance scripts.

  • Behavior:

    - Manually triggered via Azure Portal, API, or CLI.
- Scheduled using Azure Scheduler or TimerTrigger (if using WebJobs SDK).

  • Example: Nightly database cleanup or report generation.

Summary Table

Type Execution Mode Trigger Common Use Cases
Continuous WebJob Always running Starts automatically Real-time queue processing
Triggered WebJob Runs on demand Manual or scheduled Scheduled maintenance tasks

** Notes**

  • Both types support various programming languages and scripts (.exe, .cmd, PowerShell, Python, etc.).
  • Continuous jobs consume resources continuously, so use carefully to avoid excess cost.

3. View logs of WebJobs.

📄 How to View Logs of Azure WebJobs

Azure WebJobs provide built-in logging capabilities to monitor the execution and diagnose issues. Logs can be accessed through several methods.

Ways to View WebJob Logs

1. Azure Portal

  • Navigate to your App Service in the Azure Portal.
  • Select WebJobs under the Settings section.

  • Click on the specific WebJob.

  • Use the Logs tab to view output logs, including:

    - Invocation history
- Console output
- Error messages

** 2. Kudu Console**

  • Go to your App Service's Advanced Tools (Kudu) by navigating to:

4. CRON expressions

⏰ CRON Expressions Overview

What is a CRON Expression?

  • A CRON expression is a string used to define schedules for running tasks periodically.
  • Commonly used in schedulers like Azure WebJobs, Azure Functions TimerTrigger, Linux cron jobs, Jenkins, etc.

CRON Format (Standard 6 or 7 fields)

Field Allowed Values Description
Seconds 0-59 Seconds
Minutes 0-59 Minutes
Hours 0-23 Hours (24-hour format)
Day of Month 1-31 Day of the month
Month 1-12 or JAN-DEC Month
Day of Week 0-6 or SUN-SAT Day of the week (0=Sun)
Year (optional) 1970–2099 Year (optional)

Special Characters

Character Meaning
* All values
, Value list separator
- Range of values
/ Step values (increments)
? No specific value (Day of Month or Day of Week)
L Last day of the week or month
W Nearest weekday
# Nth day of the week of the month

Example CRON Expressions

Expression Meaning
0 0 * * * * Every hour at minute 0 and second 0
0 0 12 * * ? Every day at 12:00 PM
0 15 10 ? * MON-FRI At 10:15 AM every weekday (Mon-Fri)
0 0/5 * * * * Every 5 minutes
0 0 0 1 * ? At midnight on the 1st day of every month

Notes

  • Azure Functions TimerTrigger uses a 6-field CRON (seconds included).
  • Make sure to test CRON expressions with online tools like crontab.guru.

5. Always on importance in continous webjob

🔄 Importance of "Always On" in Continuous WebJobs

What is "Always On"?

  • "Always On" is an App Service setting that keeps your web app (and its associated WebJobs) running continuously, even when there is no HTTP traffic.
  • By default, Azure may idle or sleep your app after a period of inactivity to save resources.

Why is "Always On" Important for Continuous WebJobs?

  • Continuous WebJobs require the app to be always running to ensure the background job executes without interruption.

  • If "Always On" is disabled:

    - The App Service may go idle after inactivity.
- Continuous WebJobs will **stop running** until the app is accessed again.
- This leads to missed processing, delays, or failure in real-time tasks.

Key Points

Aspect Explanation
Keeps App Active Prevents app from unloading due to inactivity
Ensures WebJob Runs Continuous WebJobs keep running as expected
Required for Real-time Processing Necessary for tasks like queue monitoring, event processing
Only Applies to App Service Plans Not available for Free or Shared tiers

How to Enable "Always On"

  1. Go to your App Service in the Azure Portal.
  2. Under Settings, select Configuration.
  3. Select the General settings tab.
  4. Set Always On to On.
  5. Save the changes.

Summary

  • For reliable execution of Continuous WebJobs, always enable Always On.
  • Without it, your continuous background tasks may be paused, causing unexpected downtime.

6. Storage accounts in Webjobs

💾 Storage Accounts in Azure WebJobs

Overview

  • Azure WebJobs often rely on Azure Storage Accounts to enable messaging, state management, and logging.

  • Storage accounts provide:

  • Queues: For triggering and coordinating WebJobs.

  • Blobs: For storing input/output data.
  • Tables: For storing metadata or state information.

Role of Storage Accounts in WebJobs

Feature Purpose
Queue Storage WebJobs SDK can listen to Azure Queues to trigger job execution (e.g., process messages).
Blob Storage Input/output bindings for file processing or status data.
Table Storage Store execution logs, checkpoints, or metadata for WebJobs.
Logging & Monitoring WebJobs SDK uses storage accounts to persist logs and runtime status.

Why Use Storage Accounts with WebJobs?

  • Triggering: Many WebJobs run in response to queue messages or blob changes.
  • Scalability: Storage queues decouple producers and consumers for load leveling.
  • Durability: Durable storage ensures reliable processing and retry mechanisms.
  • Monitoring: Tracks job executions and failures for diagnostics.

Configuration

  • WebJobs SDK requires a connection string to an Azure Storage Account.
  • This is usually set in the appsettings.json or Azure Portal under Application Settings as AzureWebJobsStorage.
  • Example connection string format:

DefaultEndpointsProtocol=https;AccountName=youraccount;AccountKey=yourkey;EndpointSuffix=core.windows.net

Best Practices

  • Use a separate storage account for WebJobs to isolate workload and improve security.
  • Enable soft delete and lifecycle management on storage to protect and manage data.
  • Monitor storage account usage and scale accordingly.

Summary

Aspect Description
Storage Types Queues, Blobs, Tables
Purpose Triggering, state management, logging
Configuration Connection string via AzureWebJobsStorage
Best Practice Use dedicated storage accounts for WebJobs

7. Publish website and webjob using VS

🚀 Publish Website and WebJob Using Visual Studio

Prerequisites

  • Visual Studio installed with Azure development workload.
  • Azure subscription with an existing App Service.
  • Website and WebJob projects ready in your solution.

Steps to Publish Website and WebJob

1. Prepare Your WebJob

  • Add your WebJob project to the solution (Console App recommended).
  • Right-click the WebJob project > Properties > Ensure output type is Console Application.

  • Add the WebJob project as a WebJob to your Web App project:

    - Right-click your **Web App project** > **Add** > **Existing Project as Azure WebJob** (in newer VS versions, or manually configure).

  • In Web App project’s properties, under Azure WebJobs tab, ensure the WebJob is configured to deploy with the web app.

2. Publish the Web App and WebJob

  • Right-click on your Web App project > Publish.
  • Choose Azure as the target.
  • Select the appropriate App Service or create a new one.
  • In the Publish settings, make sure the WebJob is included.
  • Click Publish.

3. Verify Deployment

  • After publishing, go to the Azure Portal.
  • Navigate to your App Service.
  • Under Settings, click WebJobs.
  • You should see your WebJob listed and its status (Running, Stopped).
  • You can view logs, start, stop, or run the WebJob manually from the portal.

Tips

  • For Continuous WebJobs, ensure Always On is enabled in the App Service settings.
  • For Triggered WebJobs, you can run them manually or schedule via Azure Scheduler.
  • Use Application Settings in Azure Portal to configure connection strings or environment variables.
  • Use Publish Profiles to save and reuse publish configurations.

Summary Table

Step Description
Add WebJob project Create and prepare console app as WebJob
Link WebJob to Web App Configure in Web App project to deploy WebJob
Publish Web App Use Visual Studio Publish wizard to deploy both
Verify in Azure Portal Check WebJob status and logs