[Bug]: TARGETPLATFORM argument not always populated depending on container runtime during build

[p4yl04d3r]

🐞 Bug Summary

Resolve multi-arch build issue with "docker build" not setting Argument "TARGETPLATFORM" like buildkit does with buildx does. Also, Podman 4.9.x does not populate "TARGETPLATFORM".

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🧩 Affected Component

Select the area of the project impacted:

• mcpgateway - API
• mcpgateway - UI (admin panel)
• mcpgateway.wrapper - stdio wrapper
• Federation or Transports
• [ x] CLI, Makefiles, or shell scripts
• Container setup (Docker/Podman/Compose)
• Other (explain below)

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🔁 Steps to Reproduce

1. make container-build with Podman .
2. make container-build with docker without buildx installed on the build system.

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🤔 Expected Behavior

What should have happened instead?
Successful container builds for amd64, s390x and arm64

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📓 Logs / Error Output

Paste any relevant stack traces or logs here.
Step 10/42 : WORKDIR /app
---> Running in 8905b22bf7cf
---> Removed intermediate container 8905b22bf7cf
---> 92fbfce210d4
Step 11/42 : RUN if [ "$TARGETPLATFORM" = "linux/s390x" ]; then echo "Building for s390x."; echo "export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='True'" > /etc/profile.d/use-openssl.sh; else echo "export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='False'" > /etc/profile.d/use-openssl.sh; fi
---> Running in e4eadd6e3f10
/bin/bash: line 1: TARGETPLATFORM: unbound variable
The command '/bin/bash -euo pipefail -c if [ "$TARGETPLATFORM" = "linux/s390x" ]; then echo "Building for s390x."; echo "export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='True'" > /etc/profile.d/use-openssl.sh; else echo "export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL='False'" > /etc/profile.d/use-openssl.sh; fi' returned a non-zero code: 1
make: *** [Makefile:1923: container-build] Error 1

🧠 Environment Info

You can retrieve most of this from the /version endpoint.

Key	Value
Version or commit	v1.0.0
Runtime	Python 3.11, Gunicorn
Platform / OS	Ubuntu 24.04, macOS
Container	Docker, Podman

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🧩 Additional Context (optional)

Add any configuration details, flags, or related issues.

[p4yl04d3r]

I'll work on this.
To not force the need for everyone to use docker (instead of podman), or install buildx, I am going to switch from using "TARGETPLATFORM" to checking the platform architecture within the Containerfile and Containerfile.lite.