Azure Batch Service - appsettings.json not found

Question

I am deploying a .NET Core 3.1 Console app as an Application Package to execute jobs through Azure's batch service.

When I attempt to execute the job, the execution fails with the following error:

Unhandled exception. System.IO.FileNotFoundException: The configuration file 'appsettings.json' was not found and is not optional. The physical path is '/mnt/batch/tasks/workitems/FeedUpdates_Prod/job-1/FeedUpdate-20200107_1/wd/appsettings.json'.
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.HandleException(ExceptionDispatchInfo info)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load(Boolean reload)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load()
   at Microsoft.Extensions.Configuration.ConfigurationRoot..ctor(IList`1 providers)
   at Microsoft.Extensions.Configuration.ConfigurationBuilder.Build()
   at Microsoft.Extensions.Hosting.HostBuilder.BuildAppConfiguration()
   at Microsoft.Extensions.Hosting.HostBuilder.Build()
   at App.jobs.Program.Main(String[] args) in C:\Development\app\app\app.jobs\Program.cs:line 24
Aborted (core dumped)

Here is the code where I am setting up the host and instructing it to use the json file (note that it gets the same error whether the config.SetBasePath line is called or not).

        public static IHostBuilder CreateHostBuilder(string[] args)
        {
            return Host.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration((hostingContext, config) =>
                {
                    config.SetBasePath(Directory.GetCurrentDirectory());
                    config.AddJsonFile(
                       "appsettings.json", optional: false, reloadOnChange: false);
                    config.AddCommandLine(args);
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });

        }

The appsettings.json file is included in the application package I uploaded but is not present in the directory it's looking in ('/mnt/batch/tasks/workitems/FeedUpdates_Prod/job-1/FeedUpdate-20200107_1/wd/appsettings.json') so the message is accurate but I'm unclear as to why it's looking in that particular folder or how to tell it to look in the application's folder.

This is the command being executed to fire the job:

/bin/sh -c $AZ_BATCH_APP_PACKAGE_app_jobs"/app.Jobs -jFeedUpdate" 

File Listing Showing appsettings.json

Answer 1

I would recommend reading through this document: https://learn.microsoft.com/en-us/azure/batch/batch-application-packages

envinroment var access I think this is the wrong location you are looking at, please refer to this : https://learn.microsoft.com/en-us/azure/batch/batch-application-packages#execute-the-installed-applications

Idea for physical location: you can remote into the node or use tool like Batch-explorer to see where the right directory level is but if I am not wrong the task level application packages are residing usually at: /mnt/batch/tasks/applications/ folder level (I think).

Answer 2

Your stack trace shows the directory your code is trying to load the configuration file from:

Unhandled exception.
System.IO.FileNotFoundException:
The configuration file 'appsettings.json' was not found and is not optional.
The physical path is '/mnt/batch/tasks/workitems/FeedUpdates_Prod/job-1/FeedUpdate-20200107_1/wd/appsettings.json'.

This folder is the task working directory.

Application packages aren't downloaded into the task working directory because they can be used by multiple tasks - this is why your commandline needs to use the environment variable $AZ_BATCH_APP_PACKAGE_app_jobs.

In your code snippet, you have this line:

config.SetBasePath(Directory.GetCurrentDirectory());

This is setting the current directory as the location from which to load the configuration file.

Instead, you want to load the configuration file from the deployment location of the console application itself.

I'm not familiar with the way ASP.NET Core handles configuration, but I would expect the directory you need to be available on hostingContext.

Modify your call to config.SetBasePath() to pass the directory containing your application; you should then be able to load your configuration file.

Answer 3

I was able to work around this by adding the appsettings as a Resource to the task which then brought it into the working directory.

It's not ideal and I don't understand why it can find the executable and supporting files but not the appsettings which is located in the same application package so if anyone has an answer to that, I'd like to know.