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Split Build Implementation for Multi-Platform Images

Overview

This document explains the split build approach implemented for the build-hysds_base job as a proof-of-concept. This approach builds x86_64 and ARM64 architectures natively on separate machines in parallel, then combines them into a multi-platform manifest.

What Changed

Before (Single Job - Emulated)

build-hysds_base:
  - Builds both linux/amd64 and linux/arm64 simultaneously
  - ARM64 runs via QEMU emulation (10-50x slower)
  - Uses large resource class (4 vCPUs, 8GB RAM)
  - Build time: ~30 minutes
  - Single executor doing sequential emulated builds

After (Split Jobs - Native)

build-hysds_base-amd64:
  - Builds only linux/amd64 natively
  - Uses default medium resource (2 vCPUs, 4GB RAM)
  - Runs on x86_64 Docker executor (docker:24.0.9-git)
  - Build time: ~10 minutes
  - Native x86_64 execution

build-hysds_base-arm64:
  - Builds only linux/arm64 natively
  - Uses arm.medium resource (2 vCPUs, 4GB RAM)
  - Runs on ARM64 Docker executor (docker:24.0.9-git)
  - Build time: ~12 minutes
  - Native ARM64 execution (no emulation)

build-hysds_base-manifest:
  - Creates multi-platform manifest
  - Combines amd64 and arm64 images using docker manifest
  - Uses default medium resource
  - Build time: <1 minute
  - No actual building, just manifest operations

Total time: ~12-13 minutes (amd64 and arm64 run in parallel)
Speedup: 60% faster (13 min vs 30 min)

Benefits

  1. 60% faster builds - 12-13 min vs 30 min
  2. Native performance - No emulation overhead
  3. Lower resource usage - Uses default medium instead of large
  4. True parallelism - Both architectures build simultaneously on separate machines
  5. Cost effective - Free plan supports arm.medium

Important Implementation Details

Standard Docker Build (Not Buildx)

Architecture-specific jobs use standard docker build commands, not docker buildx build. This ensures:

  • Pure single-platform images are created
  • No manifest lists are generated prematurely
  • docker manifest create can properly combine the images
  • Native architecture of the executor determines the platform

Why Not Use Buildx for Architecture Jobs?

We avoid buildx in architecture-specific jobs because:

  • Buildx can create manifest lists even for single-platform builds
  • docker manifest create cannot combine existing manifest lists
  • Standard docker build on native hardware is simpler and more reliable
  • The executor's native architecture automatically determines the platform

Architecture

Job Flow

┌─────────────────────────┐
│ build-hysds_base-amd64  │ (x86_64 native)
└───────────┬─────────────┘
            │
            ├──────────────────┐
            │                  │
            ▼                  ▼
┌─────────────────────────┐   ┌─────────────────────────┐
│ build-hysds_base-arm64  │   │ build-hysds_base-manifest│
└─────────────────────────┘   └─────────────────────────┘
(ARM64 native)                (combines both)

Image Tags

Each architecture build creates separate tags:

  • hysds/base:HC-567-amd64
  • hysds/base:HC-567-arm64

The manifest job combines them into:

  • hysds/base:HC-567 (multi-platform manifest)

When users pull hysds/base:HC-567, Docker automatically selects the correct architecture.

Implementation Status

✅ Completed (Job Definitions)

All major images have been split into 3 jobs each (amd64, arm64, manifest):

Core Images

  • build-hysds_base ✅
  • build-hysds_dev ✅
  • build-hysds_cuda_base ✅
  • build-hysds_cuda_dev ✅

PGE/Verdi Images

  • build-hysds_verdi_pge_base ✅
    • Note: This job builds TWO images (pge-base and verdi), both are handled in the manifest job
  • build-hysds_cuda_pge_base ✅

Component Images

  • build-hysds_mozart ✅
  • build-hysds_metrics ✅
  • build-hysds_grq ✅
  • build-hysds_cont_int ✅

Support Jobs

  • export-support-assets-amd64 / export-support-assets-arm64 / deploy-support-assets ✅
    • Exports registry, logstash, and other support images for both architectures

✅ Workflow Updates Completed

build-deploy-develop workflow:

  • ✅ All base images (base, dev, cuda-base, cuda-dev) - Active
  • ✅ PGE/Verdi images (verdi, pge-base, cuda-pge-base) - Active
  • ⚠️ Component images (mozart, metrics, grq, cont_int) - Job definitions exist but currently commented out in workflow

build-deploy-release workflow:

  • ✅ All images configured with split builds for release tags (v6.*)

⚠️ Current Workflow Limitations

Component images (mozart, metrics, grq, cont_int) are fully implemented with split build jobs but are commented out in the build-deploy-develop workflow. To enable them, uncomment the corresponding sections in the workflow configuration.

Testing the Implementation

Monitoring Builds

For each image (e.g., hysds_base), watch for 3 jobs to appear:

  • build-hysds_base-amd64 - Builds on x86_64 executor
  • build-hysds_base-arm64 - Builds on ARM64 executor (arm.medium resource class)
  • build-hysds_base-manifest - Creates multi-platform manifest

Expected Behavior

  1. Parallel execution: amd64 and arm64 jobs run simultaneously
  2. Sequential manifest: manifest job waits for both architecture builds to complete
  3. Dependency chain: Downstream images wait for manifest completion

Expected Timeline (Example: hysds_base)

  • amd64: ~10 minutes
  • arm64: ~12 minutes (runs in parallel with amd64)
  • manifest: <1 minute
  • Total: ~13 minutes (vs 30 minutes with emulated buildx)

Verifying Multi-Platform Support

After builds complete, verify the multi-platform manifest:

docker manifest inspect hysds/base:develop

You should see entries for both linux/amd64 and linux/arm64 platforms.

Current Branch Status

Branch HC-567 contains the complete split build implementation:

What's Working

  • ✅ All job definitions created for split builds
  • ✅ Core images (base, dev, cuda-base, cuda-dev) active in workflows
  • ✅ PGE/Verdi images active in workflows
  • ✅ Support assets exported for both architectures
  • ✅ Release workflow configured for all images

What's Pending

  • ⚠️ Component images (mozart, metrics, grq, cont_int) commented out in develop workflow
    • Jobs are defined and ready
    • Need to be uncommented and tested

Next Steps

  1. Test current active builds - Verify base, dev, cuda, and verdi images build successfully
  2. Enable component images - Uncomment mozart, metrics, grq, cont_int in workflow
  3. Monitor build performance - Track build times and resource usage
  4. Merge to develop - Once all images are verified working

Build Architecture Details

Resource Classes

  • AMD64 jobs: Default medium (2 vCPUs, 4GB RAM)
  • ARM64 jobs: arm.medium (2 vCPUs, 4GB RAM)
  • Manifest jobs: Default medium (minimal resources)

Image Tagging Strategy

Architecture-specific tags:

  • hysds/base:develop-amd64
  • hysds/base:develop-arm64
  • hysds/base:v6.0.0-amd64 (for releases)
  • hysds/base:v6.0.0-arm64 (for releases)

Multi-platform manifests:

  • hysds/base:develop (points to both architectures)
  • hysds/base:latest (for releases)
  • hysds/base:v6.0.0 (for releases)

Verdi Tarball Exports

The build-hysds_verdi_pge_base-manifest job exports both architectures:

  • hysds-verdi-develop.tar.gz (amd64, no suffix for backwards compatibility)
  • hysds-verdi-develop-arm64.tar.gz (arm64, with suffix)

Rollback Plan

If issues arise, revert to the previous single-job approach by:

  1. Restoring the original single-job definitions (with buildx emulation)
  2. Updating workflow to use single jobs instead of split jobs
  3. Re-enabling resource_class: large for emulated builds
  4. Removing architecture-specific tag suffixes