UbuntuChiseledWorkerService: A C# repository from alexsteeel

Project Description

This project demonstrates debugging an application inside a Docker container using JetBrains Rider, specifically designed for Ubuntu Chiseled environments.
A related discussion is available at the GitHub issue: dotnet/dotnet-docker#4942.

Initial Issue Description

The issue arose when attempting to debug a .NET application in a Docker container.
The following error was encountered:

You must install or update .NET to run this application.

App: /app/bin/Debug/net8.0/UbuntuChiseledWorkerService.dll
Architecture: x64
Framework: 'Microsoft.AspNetCore.App', version '8.0.0' (x64)
.NET location: /usr/share/dotnet/

No frameworks were found.

Learn more:
https://aka.ms/dotnet/app-launch-failed

To install missing framework, download:
https://aka.ms/dotnet-core-applaunch?framework=Microsoft.AspNetCore.App&framework_version=8.0.0&arch=x64&rid=linux-x64&os=debian.12

Testing Process

Scenario 1: Clean WorkerService

This scenario tests the basic functionality of a WorkerService without any additional packages.

Dockerfile	Result
`FROM mcr.microsoft.com/dotnet/runtime:8.0 AS base`	Works
`FROM mcr.microsoft.com/dotnet/runtime:8.0-noble-chiseled AS base`	Works
`FROM mcr.microsoft.com/dotnet/aspnet:8.0.7-noble-chiseled-extra-amd64 AS base`	Works
`FROM mcr.microsoft.com/dotnet/sdk:8.0 AS base`	Works

Scenario 2: Adding a Package that Depends on ASP.NET Core

This scenario adds a package that requires ASP.NET Core, for instance, prometheus-net.AspNetCore.

Dockerfile	Result
`FROM mcr.microsoft.com/dotnet/runtime:8.0 AS base`	Does not work
`FROM mcr.microsoft.com/dotnet/runtime:8.0-noble-chiseled AS base`	Does not work
`FROM mcr.microsoft.com/dotnet/aspnet:8.0.7-noble-chiseled-extra-amd64 AS base`	Works
`FROM mcr.microsoft.com/dotnet/sdk:8.0 AS base`	Works

Scenario 3: Testing Multi-Stage Builds

This scenario explores the order and naming of stages in multi-stage Dockerfiles.

Incorrect Order:

FROM mcr.microsoft.com/dotnet/runtime:8.0 AS service
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS base

Result: Does not work (uses the first stage).

Correct Order:

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS base
FROM mcr.microsoft.com/dotnet/runtime:8.0 AS service

Result: Works.

No Stage Name for the First Image:

FROM mcr.microsoft.com/dotnet/runtime:8.0
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS base

Result: Does not work (uses the first named stage).

Adding a Debug Stage at the Start:

FROM mcr.microsoft.com/dotnet/aspnet:8.0.7-noble-chiseled-extra-amd64 as debug
FROM mcr.microsoft.com/dotnet/runtime:8.0 AS service
FROM mcr.microsoft.com/dotnet/aspnet:8.0.7-noble-chiseled-extra-amd64 as publish

Result: Works.

Final Issue Diagnosis

The issue arose from the initial inclusion of a service image based on mcr.microsoft.com/dotnet/runtime:8.0, which was intended to prepare files for subsequent stages. However, because Rider (the IDE being used) defaults to using the first available named stage, the presence of a package that required ASP.NET Core led to the error.

Solution

To resolve this issue, you can:

Add a Debug Stage:
- Insert an additional debug stage with the necessary image at the beginning of the Dockerfile. Since this stage is not used elsewhere, it will not impact the performance of the final image build.
Example:
```
FROM mcr.microsoft.com/dotnet/aspnet:8.0.7-noble-chiseled-extra-amd64 as debug
FROM mcr.microsoft.com/dotnet/runtime:8.0 AS service
FROM mcr.microsoft.com/dotnet/aspnet:8.0.7-noble-chiseled-extra-amd64 as publish
```
Create a Separate Debug Dockerfile:
- Alternatively, create a separate DebugDockerfile with just the necessary image and specify this Dockerfile in the debugging settings of your IDE.
Set Build Options in Rider:
- In Rider, you can set specific build options for your Dockerfile in the settings of the debug profile. For example, you can use the --target option to specify which stage to use during the build process. This ensures that the correct stage is selected and avoids the issue of the IDE defaulting to the first available named stage.
Example Option:
- In the debug profile settings, add --target publish to ensure that Rider builds the correct stage of your Dockerfile.

This approach ensures that the build process is consistent and avoids the issues related to the default stage selection behavior in the IDE, providing multiple solutions depending on your workflow and setup.

alexsteeel/UbuntuChiseledWorkerService