Key Takeaways & Resolutions:

Local Cross-Platform Build Challenges: Attempting to build Docker images for a different CPU architecture locally (e.g., target linux/amd64 from an arm64 host like Apple Silicon M1/M2/M3) using emulation (docker buildx) can lead to extreme build times (often >10x slower than native) or even hangs, likely due to CPU emulation overhead and potential resource constraints. This proved unreliable for complex builds.

CI/CD for Cross-Platform Builds: Utilizing a CI/CD platform like GitHub Actions is a highly effective solution. By selecting a runner that natively matches the target architecture (e.g., runs-on: ubuntu-latest for amd64 builds), the build executes quickly and reliably, avoiding local emulation issues.

Build-Time Dependencies in CI: Docker builds executed within CI/CD environments may fail if they require access to environment variables (e.g., API keys, database URIs) or external resources during the build process itself. These dependencies must be explicitly provided to the CI build environment.

Securely Providing Build Secrets: Necessary build-time secrets and variables should be securely injected into the CI/CD build. Using the CI platform’s secret management (e.g., GitHub Secrets) combined with Docker build arguments (–build-arg in the build command, ARG/ENV in Dockerfile) is a standard secure practice.

CI/CD Push Permissions: Pushing images from CI/CD workflows to container registries (like GHCR, Docker Hub, etc.) requires careful permission setup for the token/credentials used:

Workflow Definition: The workflow must request the necessary permissions (e.g., permissions: packages: write for GitHub Actions pushing to GHCR).

Platform Settings: The CI/CD platform’s repository and/or organization settings must allow the workflow’s token (e.g., GITHUB_TOKEN) to be granted these permissions (e.g., GitHub repo setting “Read and write permissions” for Actions).

Registry/Package Settings: Specific container registry or package-level settings might also need configuration to allow writes from the CI/CD process.

Accessing Private Images: When deploying private container images, the deployment environment (e.g., server, Kubernetes cluster) needs to be authenticated to the container registry to pull the image (e.g., using docker login with appropriate credentials like a Personal Access Token with read scope).