CronSchedulerApp

CronSchedulerApp

Note: Pre-release packages are distributed via feedz.io.

This ASP.NET Core web application demonstrates various scheduled jobs and how to use them. It includes examples of background tasks, startup jobs, and scheduled jobs using the CronScheduler library.

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Using Scheduled Jobs in ASP.NET Core Web Application

This application demonstrates how to use scheduled jobs in an ASP.NET Core web application. The application leverages the CronScheduler library to manage and execute scheduled tasks. Below are the steps to add and configure scheduled jobs:

Job Details

SeedDatabaseStartupJob

This job demonstrates how to use EF context to seed the database before any request is served. It ensures that the database exists and creates 5 users.

UserJob

This job demonstrates how to add a claim to each user in the database. It retrieves users from the database and adds a claim with the current UTC time.

TestJob

This job is a simple test job that logs its execution. It will be removed in the next release.

TorahQuoteJob

This job retrieves a random verse from the Torah and updates the current verses in the TorahVerses service.

Adding a Scheduled Job

1. Create a Job Class: Implement the IScheduledJob interface in your job class. For example:

   using System;
   using System.Threading;
   using System.Threading.Tasks;
   using CronScheduler.Extensions.Scheduler;
   using Microsoft.Extensions.Logging;
   
   public class MyScheduledJob : IScheduledJob
   {
       private readonly ILogger<MyScheduledJob> _logger;
   
       public MyScheduledJob(ILogger<MyScheduledJob> logger)
       {
           _logger = logger ?? throw new ArgumentNullException(nameof(logger));
       }
   
       public string Name { get; } = nameof(MyScheduledJob);
   
       public async Task ExecuteAsync(CancellationToken cancellationToken)
       {
           _logger.LogInformation("Executing scheduled job: {jobName}", Name);
           // Your job logic here
           await Task.CompletedTask;
       }
   }

2. Configure Job Options: Create a class that inherits from SchedulerOptions to define job-specific options.

   using CronScheduler.Extensions.Scheduler;
   
   public class MyScheduledJobOptions : SchedulerOptions
   {
       public string SomeOption { get; set; } = string.Empty;
   }

3. Register the Job: In your Program.cs or Startup.cs, register the job and its options with the scheduler. Additionally, add a custom error processing for internal errors using an unobserved task exception handler.

   services.AddScheduler(builder =>
   {
       builder.AddJob<MyScheduledJob, MyScheduledJobOptions>();
   });
   
   // Add a custom error processing for internal errors
   builder.AddUnobservedTaskExceptionHandler(sp =>
   {
       var logger = sp.GetRequiredService<ILoggerFactory>().CreateLogger("CronJobs");
       return (sender, args) =>
       {
           logger?.LogError(args.Exception?.Message);
           args.SetObserved();
       };
   });

Adding Jobs on the Fly

Jobs can also be added on the fly and configured from a database class where the options are stored using the following syntax:

var jobOptions = await _dbContext.JobOptions.FindAsync("TestJob");
_schedulerRegistration.AddOrUpdate(new TestJob(jobOptions, _loggerFactory.CreateLogger<TestJob>()), jobOptions);

Sample Job Options

Below are sample options for configuring the jobs in the appsettings.json file:

{
  "SchedulerJobs": {
    "TorahQuoteJob": {
      "RunImmediately": true,
      "ApiUrl": "http://labs.bible.org/api/",
      "WebsiteUrl": "https://studybible.info/KJV_Strongs",
      "CronSchedule": "0/10 * * * * *",
      "Verses": [
        "Genesis 1:1-3",
        "Exodus 3:14-15",
        "Isaiah 53",
        "Isaiah 26:18",
        "Proverbs 14:23",
        "Daniel 12:1-12"
      ]
    },
    "UserJob": {
      "RunImmediately": true,
      "CronSchedule": "2 9 * * *",
      "ClaimName": "TestClaim"
    }
  }
}

Running the Application

Docker Container

1. Build the Docker Image: Use the following command to build the Docker image.

   docker build --pull --rm -f "src/CronSchedulerApp/Dockerfile" -t cronscheduler:latest .

2. Run the Docker Container: Use the following command to run the Docker container.

   docker run --rm -d -p 4443:443/tcp -p 8080:80/tcp cronscheduler:latest

Run dotnet

1. Build and Run: Build and run your application using the following commands. The scheduled jobs will be executed based on their configured schedules.

   # Navigate to the project directory
   cd src/CronSchedulerApp
   
   # Build the project
   dotnet build
   
   # Run the project
   dotnet run