Optimizing Docker Build Performance on Namespace Runners

Building Docker images can be one of the most time-consuming parts of your CI/CD pipeline. Namespace runners are designed to dramatically accelerate your Docker builds through intelligent build distribution, advanced caching, and seamless integration with your existing workflows.

Quick Start: Instant Performance Gains

No configuration changes required

The fastest way to speed up your Docker builds is to simply switch to Namespace runners. Remote Builders are enabled by default and will immediately accelerate your builds.

jobs:
  build:
    runs-on: namespace-profile-default # was: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        # No docker/setup-buildx-action or docker/setup-qemu-action required!
      - name: Build and push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: my-registry/my-app:latest

Note: If your workflow uses docker/setup-buildx-action, you need to remove or replace it.

That's it! Your builds are now running on high-performance Remote Builders with advanced caching.

Understanding Remote Builders: Your Build Acceleration Engine

How Remote Builders Transform Your Workflow

Remote Builders fundamentally change how Docker builds work in your CI/CD pipeline:

• Scale independently: Massive parallel compute power regardless of your runner size
• Cost optimization: Use smaller, cheaper runners while getting maximum build performance
• Zero configuration: Every Docker command automatically benefits from remote acceleration
• Universal compatibility: Works with docker build, docker/build-push-action, and any Docker-based tooling

Monitoring Your Accelerated Builds

Every build launched from your runners appears in the interface providing direct access to detailed logs, timing metrics, and performance analytics.

This visibility helps you understand exactly how much time Remote Builders are saving. When looking at a slow build step, you can directly jump into the logs to understand which work was performed.

Head to Build Observability → to learn how to monitor build performance and identify bottlenecks.

Seamless Private Registry Integration

Your builds get instant access to your private container registry at nscr.io with zero setup required. Authentication is handled automatically.

- name: Build and push to private registry
  uses: docker/build-push-action@v5
  with:
    context: .
    push: true
    tags: ${{ env.NSC_CONTAINER_REGISTRY }}/my-app:${{ github.sha }}

- name: Use base image from private registry
  run: docker pull ${{ env.NSC_CONTAINER_REGISTRY }}/my-app:${{ github.sha }}

You can find a tag overview with history and usage statistics for pushed images in the dashboard.

When to Choose Local Caching

While Remote Builders provide the best performance for most scenarios, in-runner builders (locally cached) excel when building massive images (10GB+). Keeping the build local skips network transfer time.

With runner profilesWith runner labels

To enable this feature, just open the runner profile configuration and add a cache volume. Next, select Locally cached for your Docker builds.

Caveats

• Build caching using "local caching" is not shared with Remote Builders; each repository uses its own separate cache.
• Although multi-platform builds are supported, only builds of the same platform as the runner itself, will experience native performance.

Billing

Using local caching does not lead to any additional compute usage beyond the runner's execution time itself. In order to make use of the feature, including logging and tracing, each build made with local caching counts towards the total build usage.

Enterprise Build Scaling

Need to run hundreds of concurrent builds? Namespace supports full-fanout builds that can handle enterprise-scale build volumes without performance degradation.

• Automatic scaling: Remote Builders support automatic scale-out to match your build volume
• No queue bottlenecks: Parallel processing ensures builds start immediately
• Dedicated compute: With dedicated Namespace compute, you get a fully consistent build performance experience

Contact support@namespace.so to discuss custom scaling configurations for your build volume requirements.

Migrating from GitHub Actions

Why you should skip setting up buildx yourself

Because Namespace runners are configured out of the box to use Remote Builders, there is no need to set up or configure buildx separately. In fact, running docker/setup-buildx-action will overwrite the default configuration and prevent you from using Remote Builders.

You can just remove docker/setup-buildx-action from your workflow entirely,
or replace it with namespacelabs/nscloud-setup-buildx-action:

  - name: Set up Docker Buildx
-   
uses: docker/setup-buildx-action@v3
+   
uses: namespacelabs/nscloud-setup-buildx-action@v0
  - uses: docker/build-push-action@v5
    with:
      context: .

Setting up QEMU is not necessary

Multi-platform builds using Remote Builders don't use emulation for AMD64 and ARM64 builds, instead building on these platforms natively. This results in much better performance for multi-platform builds, and also means there is no need to set up QEMU.

When using Remote Builders, you can safely remove docker/setup-qemu-action, too:

steps:
  
- uses: docker/setup-qemu-action@v3
  
- uses: docker/setup-buildx-action@v3
  - uses: docker/build-push-action@v5
    with:
      context: .

Why you can skip GitHub Actions Caching

Traditional CI/CD requires complex caching strategies, but Namespace's build infrastructure makes this unnecessary. Namespace build solutions include maximum layer caching out of the box. Using traditional GitHub actions caching like cache-from/cache-to is superfluous when using Namespace builders and typically adds delays through remote file operations.

You can remove them from your workflow definition:

- uses: docker/build-push-action@v5
  with:
    context: .
    
cache-from: type=registry,ref=user/app:buildcache
    
cache-to: type=registry,ref=user/app:buildcache,mode=max

What This Means for You

• No cache configuration: Remove complex caching logic from your workflows
• Faster cold starts: Even first builds benefit from shared layer caches
• Consistent performance: Cache hit rates are optimized automatically