Add support to build MCP Gateway for s390x platform

[p4yl04d3r]

✨ Feature / Enhancement PR

🔗 Epic / Issue

Link to the epic or parent issue:
Closes #1138

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🚀 Summary (1-2 sentences)

What does this PR add or change?
This feature adds support to build MCP gateway container for s390x platform.

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🧪 Checks

• make lint passes
• make test passes
• CHANGELOG:
  Update Makefile to address issue that prevents podman from being used as container runtime when docker is not installed.
  Update Makefile to add "linux/s390x" to "container-build-multi"
  Added s390x support to Container.lite and Container files to successfully build "linux/s390x" container.

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📓 Notes (optional)

Design sketch, screenshots, or extra context.

If the change introduces or alters an architectural decision, add or update an ADR in docs/docs/adr/ and link it here._

%% Example diagram - delete if not needed
flowchart TD
    A[Client] -->|POST /completions| B(MCPGateway)
    B --> C[Completion Service]

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[jonpspri]

@crivetimihai Feel free to add me as a reviewer here. I need an excuse to fire up an s390x qemu today.

[MohanLaksh]

Thanks for the contribution Chris (@p4yl04d3r).

Please review the below code and let me know your thoughts.

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Hi @p4yl04d3r , Can we do this instead (in both Containerfile and .lite file)?

RUN set -eux;
if [ "$TARGETPLATFORM" = "linux/s390x" ]; then
echo "Building for s390x platform.";
echo 'export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL=True' > /etc/profile.d/use-openssl.sh;
else
echo "Building for other platform: $TARGETPLATFORM.";
echo 'export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL=False' > /etc/profile.d/use-openssl.sh;
fi

RUN chmod 644 /etc/profile.d/use-openssl.sh

I have made the following suggestions:

1. set -eux - Fail fast and loud
2. using export
3. Single > instead of >> ... Writes a fresh file instead of appending on rebuilds.
4. Changed permission to readable by all since it is a sourced script. No need to be executable
5. Used single quotes ' to avoid Hadolint issues

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PR REVIEW SUMMARY:

1. make serve - PASS

2. make test - PASS - (Coverage: , 73%, === 3392 passed, 45 skipped, 949 warnings in 458.32s (0:07:38) ===)

3. make autoflake isort black flake8 - PASS - No major code formatting/clean-up issues detected.

4. make pylint - PASS - Your code has been rated at 10.00/10

5. make smoketest - PASS - ✅ Smoketest passed!

6. make doctest - PASS - (Coverage: 41%, 782 passed, 8 skipped, 99 warnings in 46.94s)

[p4yl04d3r]

Changes have been made to the 2 files as suggested.

[MohanLaksh]

Hi @jonpspri,
Can you help us review this please?