Run MessagingService container as a non-root user

[Copilot]

Codacy flagged MessagingService/Dockerfile because the final Linux container image did not specify a runtime user, allowing the process to run as root. This change sets an explicit non-root user in the final image stage.

• Container runtime hardening

  • Added an explicit USER directive to the final stage of MessagingService/Dockerfile
  • Ensures dotnet MessagingService.dll does not start as root by default

• Scope

  • Limited to the final runtime image stage
  • No changes to build/publish steps or application behavior

• Resulting Dockerfile change

  FROM base AS final
  WORKDIR /app
  COPY --from=publish /app/publish .
  USER 10001
  ENTRYPOINT ["dotnet", "MessagingService.dll"]

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• f.feedz.io
  • Triggering command: /usr/bin/dotnet dotnet restore MessagingService.sln (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore MessagingService/MessagingService.csproj (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Security] By not specifying a USER, a program in the container may run as 'root'. This is a security hazard.</issue_title>
<issue_description>

Codacy ID: abce298abca6d610008b217b22d765da

File: MessagingService/Dockerfile
Line: 34
Rule: Security (High)
Commit: c615e72147bf1f47ec301470ae5601fd52f5406f

Message: By not specifying a USER, a program in the container may run as 'root'. This is a security hazard.

**Code Snippet:**
```csharp
ENTRYPOINT ["dotnet", "MessagingService.dll"] 
```

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Security] By not specifying a USER, a program in the container may run as 'root'. This is a security hazard. #361

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