fix: improve Dockerfile signal handling and slim runtime

[tac0turtle]

• Use SIGINT stop signal for proper graceful shutdown
• Remove unnecessary build/debug packages from runtime image (libssl-dev, pkg-config, strace)
• Bump healthcheck start-period to 60s

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Refactoring

Related Issues

Fixes #(issue)

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Testing

Additional Notes

[gemini-code-assist]

Summary of Changes

Hello @tac0turtle, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the Docker image for the 'ev-reth' application by optimizing its runtime environment and improving container lifecycle management. The changes aim to create a leaner, more robust container that handles shutdowns gracefully and provides a more forgiving startup period for its health checks.

Highlights

• Runtime Image Optimization: Removed development and debugging packages (libssl-dev, pkg-config, strace) from the Docker runtime image to reduce its size and attack surface.
• Graceful Shutdown: Configured the Dockerfile to use SIGINT as the stop signal, enabling a more graceful shutdown process for the application within the container.
• Healthcheck Configuration: Increased the start-period for the container's healthcheck from 40 seconds to 60 seconds, providing more time for the application to initialize before health checks begin.

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Changelog

• Dockerfile
  • Removed 'libssl-dev', 'pkg-config', and 'strace' packages from the runtime image to reduce its footprint.
  • Updated the 'HEALTHCHECK' 'start-period' from 40 seconds to 60 seconds.
  • Added 'STOPSIGNAL SIGINT' to ensure proper signal handling for graceful container termination.

Activity

• No specific activity (comments, reviews, etc.) was provided in the context for this pull request.

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[claude]

Claude finished @tac0turtle's task —— View job

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Pull Request Review

Todo List:

• Read and analyze the Dockerfile changes
• Review code quality and best practices
• Check for potential bugs or issues
• Evaluate performance considerations
• Assess security concerns
• Consider test coverage implications

Review Findings

Code Quality and Best Practices ✅

The changes follow Docker best practices well:

1. Signal Handling: Adding STOPSIGNAL SIGINT (line 71) is excellent - this ensures the application receives proper shutdown signals for graceful termination instead of SIGKILL.

2. Runtime Image Optimization: Removing build/debug packages from the runtime image is a solid practice:

   • Removed: libssl-dev, pkg-config, strace
   • Kept: Essential runtime dependencies (ca-certificates, curl, jq, tini)

3. Healthcheck Tuning: Increasing start-period from 40s to 60s (line 68) gives the application more time to initialize before health checks begin.

Potential Issues ⚠️

Minor concern with package removal:

• Verify that libssl-dev removal doesn't break SSL/TLS functionality. The runtime should use libssl3 (installed with ca-certificates) but worth testing.
• Removing strace eliminates debugging capabilities in production - this is generally good but consider if you need debugging tools.

Performance Considerations 🚀

Positive impacts:

• Image Size: Removing unnecessary packages reduces image size and attack surface
• Startup: More generous healthcheck start-period reduces false negatives during startup
• Shutdown: SIGINT allows proper resource cleanup vs force-kill

No performance regressions expected from these changes.

Security Concerns 🔒

Security improvements:

• ✅ Reduced Attack Surface: Removing dev packages (libssl-dev, pkg-config, strace) eliminates potential vulnerability vectors
• ✅ Proper Signal Handling: SIGINT allows graceful shutdown and proper resource cleanup
• ✅ Minimal Runtime: Only essential packages remain in final image

No security concerns identified - these changes improve the security posture.

Test Coverage Considerations 🧪

Recommendations for testing:

• Test container startup/shutdown cycles to verify SIGINT handling works correctly
• Verify SSL/TLS connections still work after removing libssl-dev
• Confirm healthcheck behaves properly with new 60s start-period
• Test that the application still functions normally without the removed debug packages

Note: No automated tests exist in the repository for Docker functionality, but the changes are low-risk and follow established best practices.

Summary

This is a well-crafted improvement that enhances the Docker image's:

• Security posture (reduced attack surface)
• Operational robustness (proper signal handling)
• Resource efficiency (smaller image size)
• Reliability (better healthcheck timing)

The changes are minimal, focused, and follow Docker best practices. All requested review areas have been covered with no blocking issues identified.

Recommendation: ✅ Approve - These are solid improvements with no significant risks.

[gemini-code-assist]

Code Review

This pull request improves the Dockerfile by slimming the runtime image and improving signal handling. The changes are good, removing unnecessary build-time packages and setting the stop signal for graceful shutdown. I've added a couple of suggestions to further improve the Dockerfile: one to make the runtime image even smaller by avoiding recommended package installations, and another to make the healthcheck more robust by checking a live service endpoint instead of just the binary's existence. These changes will improve the container's efficiency and reliability.

[gemini-code-assist]

To further reduce the image size, it's a good practice to use the --no-install-recommends flag with apt-get install. This prevents the installation of packages that are not strictly required for the main packages to run, contributing to a slimmer runtime image.

    apt-get install -y --no-install-recommends ca-certificates curl jq tini && \

[gemini-code-assist]

The current healthcheck command only verifies that the binary is executable, not that the node service is actually running and healthy. This could lead to a situation where the container is considered healthy even if the node has crashed or is unresponsive. A more effective healthcheck would query a live service endpoint, such as the JSON-RPC API, to confirm the service is responsive.

HEALTHCHECK --interval=30s --timeout=3s --start-period=60s --retries=3 \
    CMD curl -f -X POST --data '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}' -H "Content-Type: application/json" http://localhost:8545 || exit 1