Halving CI/CD deploy time: patching manifest to skip redundant Docker build in svc package

[thomaswitt]

Problem

When using copilot svc package in a CodeBuild pipeline, Copilot triggers a full Docker build if the manifest specifies image.build. This means the image gets built twice per deployment:

1. Explicit build — docker buildx build → push to ECR (the one you actually want)
2. Implicit rebuild — copilot svc package sees image.build and rebuilds, even though the image already exists in ECR

Docker layer caching in CodeBuild was also unreliable in our setup, so each redundant build was essentially a from-scratch build every time.

Solution

Before the svc package loop, patch the manifest to replace image.build with image.location pointing to the already-pushed ECR image:

# Backup web manifest before patching (immutable source for awk)
cp copilot/web/manifest.yml /tmp/web_manifest_original.yml

for env in $STAGES; do
  DEPLOY_TAG=$(echo "${CODEBUILD_BUILD_ID##*:}-${env}" | tr ':' '-' | rev | cut -c 1-128 | rev)
  export TAG="$DEPLOY_TAG"

  # Patch web manifest: replace image.build with image.location
  # so copilot svc package skips the redundant Docker build
  awk -v loc="  location: ${ECR_REPO}:${TAG}" '
    /^image:/ { print "image:"; print loc; print "  port: 8080"; skip=1; next }
    skip && /^[^ #]/ { skip=0 }
    !skip { print }
  ' /tmp/web_manifest_original.yml > copilot/web/manifest.yml

  for svc in $SVCS; do
    ./copilot-linux svc package -n "$svc" -e "$env" \
      --output-dir infrastructure --tag "$TAG" --upload-assets
  done
done

# Restore original web manifest
cp /tmp/web_manifest_original.yml copilot/web/manifest.yml

How it works

1. Back up the original manifest before the loop (immutable source)
2. Patch with awk — replaces the entire image: block with image.location: <ECR_REPO>:<TAG>
3. Package — copilot svc package sees image.location and skips building
4. Restore the original manifest after the loop (so git stays clean)

Result

~50% reduction in pipeline time — eliminating one full Docker build per deployment across all environments.

Setup

• Manifest: Load Balanced Web Service with image.build: Dockerfile
• Pipeline: CodeBuild → copilot svc package → CloudFormation deploy
• Platform: linux/arm64 (Graviton)

Hope this helps anyone running into the same double-build issue! 🚀