ISS-1594287: CI workflow optimisations

[parag-razor]

Summary

• Optimised Dockerfile layer ordering in the builder stage for better Docker build cache utilisation
• Moved apk add and gem install bundler before any COPY instructions so OS/bundler installation is always cached
• Separated dependency files (Gemfile.build*) from data files (data/, init.rb) so that bundle install is cached even when data files change
• Removed debug echo statements from cached layers to keep layers clean and deterministic

Why

Previously, COPY data /app/data/ and COPY Gemfile.build* init.rb /app/ were placed before apk add and bundle install. This meant that any change to the data directory or init.rb would invalidate the cache for OS package installation and gem installation layers, causing them to re-run on every build. With this fix, those expensive layers remain cached as long as the system packages and Gemfile.build haven't changed.

Changes

• Builder stage reordering:
  • RUN apk add redis && gem install bundler moved before any COPY (always cached)
  • COPY Gemfile.build* placed before bundle install (cached unless Gemfile.build changes)
  • COPY init.rb and COPY data moved after bundle install (cache-busting boundary)
  • Removed echo debug lines from cached layers 1 and 2

Test plan

• Verify Dockerfile syntax is valid
• Confirm Docker builds succeed with the reordered layers
• Verify layer caching works (second build should skip apk/bundle install if Gemfile.build unchanged)

Generated with Claude Code docker-optimisations skill