Docker Builders

In Docker, a builder is a BuildKit daemon that executes the instructions in your Dockerfile to produce a container image. While the standard Docker Engine comes with a built-in builder, modern development often uses Docker Buildx to manage multiple builder instances with different "drivers" for advanced features like multi-platform builds and remote caching.

Core Builder Drivers

docker driver

The default driver that uses the BuildKit library bundled into your local Docker Engine.

docker-container driver

Spawns a dedicated BuildKit instance inside a container. This is required for multi-platform builds (e.g., building ARM64 images on an AMD64 machine).

kubernetes driver

Runs builds as pods within a Kubernetes cluster, allowing you to scale your build infrastructure.

remote driver

Connects to a manually managed, remote BuildKit daemon, which is useful for specialized CI/CD setups.

Advanced Solutions

For teams needing more speed or specialized environments, several managed builder options exist:

• Docker Build Cloud: A managed service that offloads builds to high-performance cloud infrastructure to speed up local and CI pipelines.
• Google Cloud Build: Uses prebuilt Docker images (cloud builders) to execute tasks within a serverless pipeline.
• Packer Docker Builder: A tool from HashiCorp that builds Docker images without using Dockerfiles, often by running provisioners inside a container and then committing the result.

Essential Commands

You can manage your builders via the Buildx CLI:

docker buildx ls

List all available builders.

docker buildx create --use

Create and switch to a new builder instance.

docker buildx inspect

View details about a specific builder's capabilities

Summary of Docker Builders

Builder / Driver	Best Used For	Pros	Cons
docker (Default)	Standard local Linux development.	• Zero setup. • Uses local daemon storage.	• No multi-platform builds. • Limited advanced caching.
desktop-linux	Docker Desktop users (Mac/Win/Linux).	• Ready out-of-the-box. • Built-in QEMU emulation.	• Tied to VM resource limits. • Slow emulated builds.
docker-container	Advanced local caching & multi-platform.	• Isolated sandbox. • Concurrent builds.	• Requires quick initial setup. • Images not auto-loaded to host.
kubernetes	Enterprise CI/CD pipelines.	• Scales automatically. • Offloads heavy host builds.	• Cluster management overhead. • Complex RBAC setup.
remote	Centralised team build servers.	• Saves local host resources. • Centralised team caching.	• Manual setup required. • Requires TLS certificate management.
Cloud Services (Docker Build Cloud / Depot)	Fast multi-architecture team builds.	• Native ARM/AMD hardware. • Instant shared caching.	• Requires paid subscriptions. • Needs internet connectivity.