[Bug]: Deployment to Container Apps not working

[Vaughn1234]

What happened?

I followed the tutorial at https://learn.microsoft.com/en-us/azure/data-api-builder/mcp/quickstart-azure-container-apps to create an mcp server for an Azure SQL Server using DAB and a container app. I followed all steps, and all of the ressources have been deployed, but the health check returns a 503 Error. Checking the container logs, it is complaining about dab-config.json not being found. In the linked tutorial, the config is only stored as a base64 string in an environment variable. Is it possible that a step is missing where the dab-config.json is then created from this environment variable? There is no dab-config.json in the App directory on the container.

Locally, I am able to run it with dotnet dab start.

Version

Microsoft.DataApiBuilder 1.7.83-rc+c7927fa9885160ed35bcc9b25b13fd59b88f3133

What database are you using?

Azure SQL

What hosting model are you using?

Container Apps

Which API approach are you accessing DAB through?

REST

Relevant log output

Unable to find config file: dab-config.json does not exist.
2026-01-14T12:34:18.8305684Z stderr F Unable to find config file: dab-config.json does not exist.
2026-01-14T12:34:18.8369792Z stderr F Unable to find config file: dab-config.json does not exist.
2026-01-14T12:34:18.8573138Z stdout F info: Microsoft.Hosting.Lifetime[14]
2026-01-14T12:34:18.8573544Z stdout F       Now listening on: http://[::]:5000
2026-01-14T12:34:18.8573683Z stdout F info: Microsoft.Hosting.Lifetime[0]
2026-01-14T12:34:18.8573700Z stdout F       Application started. Press Ctrl+C to shut down.
2026-01-14T12:34:18.8573715Z stdout F info: Microsoft.Hosting.Lifetime[0]
2026-01-14T12:34:18.8573727Z stdout F       Hosting environment: Production
2026-01-14T12:34:18.8573782Z stdout F info: Microsoft.Hosting.Lifetime[0]
2026-01-14T12:34:18.8573795Z stdout F       Content root path: /App

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[Vaughn1234]

I have been able to alleviate this by adding a custom startup command that creates the dab-config.json file from the environment variable on my container.