buildkit/README.md

Important: This repository is in an early development phase

BuildKit

BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner.

Key features:

• Automatic garbage collection
• Extendable frontend formats
• Concurrent dependency resolution
• Efficient instruction caching
• Build cache import/export
• Nested build job invocations
• Distributable workers
• Multiple output formats
• Pluggable architecture

Read the proposal from https://github.com/moby/moby/issues/32925

Quick start

BuildKit daemon can be built in two different versions: one that uses containerd for execution and distribution, and a standalone version that doesn't have other dependencies apart from runc. We are open for adding more backends. buildd is a CLI utility for serving the gRPC API.

# buildd daemon (choose one)
go build -o buildd-containerd -tags containerd ./cmd/buildd
go build -o buildd-standalone -tags standalone ./cmd/buildd

# buildctl utility
go build -o buildctl ./cmd/buildctl

You can also use make binaries that prepares all binaries into the bin/ directory.

examples/buildkit* directory contains scripts that define how to build different configurations of BuildKit and its dependencies using the client package. Running one of these script generates a protobuf definition of a build graph. Note that the script itself does not execute any steps of the build.

You can use buildctl debug dump-llb to see what data is in this definition. Add --dot to generate dot layout.

go run examples/buildkit0/buildkit.go | buildctl debug dump-llb | jq .

To start building use buildctl build command. The example script accepts --target flag to choose between containerd and standalone configurations. In standalone mode BuildKit binaries are built together with runc. In containerd mode, the containerd binary is built as well from the upstream repo.

go run examples/buildkit0/buildkit.go | buildctl build

buildctl build will show interactive progress bar by default while the build job is running. It will also show you the path to the trace file that contains all information about the timing of the individual steps and logs.

Different versions of the example scripts show different ways of describing the build definition for this project to show the capabilities of the library. New versions have been added when new features have become available.

• ./examples/buildkit0 - uses only exec operations, defines a full stage per component.
• ./examples/buildkit1 - cloning git repositories has been separated for extra concurrency.
• ./examples/buildkit2 - uses git sources directly instead of running git clone, allowing better performance and much safer caching.
• ./examples/buildkit3 - allows using local source files for separate components eg. ./buildkit3 --runc=local | buildctl build --local runc-src=some/local/path
• ./examples/dockerfile2llb - can be used to convert a Dockerfile to LLB for debugging purposes
• ./examples/gobuild - shows how to use nested invocation to generate LLB for Go package internal dependencies

Examples

Starting the buildd daemon:

buildd-standalone --debug --root /var/lib/buildkit

Building a Dockerfile:

buildctl build --frontend=dockerfile.v0 --local context=. --local dockerfile=.
buildctl build --frontend=dockerfile.v0 --local context=. --local dockerfile=. --frontend-opt target=foo --frontend-opt build-arg:foo=bar

context and dockerfile should point to local directories for build context and Dockerfile location.

Building a Dockerfile using external frontend:

buildctl build --frontend=gateway.v0 --frontend-opt=source=tonistiigi/dockerfile:v0 --local context=. --local dockerfile=.
buildctl build --frontend gateway.v0 --frontend-opt=source=tonistiigi/dockerfile:v0 --frontend-opt=context=git://github.com/moby/moby --frontend-opt build-arg:APT_MIRROR=cdn-fastly.deb.debian.org

Exporting resulting image to containerd

Containerd version of buildd needs to be used

buildctl build ... --exporter=image --exporter-opt name=docker.io/username/image
ctr --namespace=buildkit images ls

Push resulting image to registry

buildctl build ... --exporter=image --exporter-opt name=docker.io/username/image --exporter-opt push=true

If credentials are required, buildctl will attempt to read Docker configuration file.

Exporting build result back to client

buildctl build ... --exporter=local --exporter-opt output=path/to/output-dir

View build cache

buildctl du -v

Running containerized buildkit

buildkit can be also used by running the buildd daemon inside a Docker container and accessing it remotely. The client tool buildctl is also available for Mac and Windows.

To run daemon in a container:

docker run -d --privileged -p 1234:1234 tonistiigi/buildkit:standalone --addr tcp://0.0.0.0:1234
export BUILDKIT_HOST=tcp://0.0.0.0:1234
buildctl build --help

The tonistiigi/buildkit:standalone image can be built locally using the Dockerfile in ./hack/dockerfiles/test.Dockerfile.

Supported runc version

During development buildkit is tested with the version of runc that is being used by the containerd repository. Please refer to runc.md for more information.

Contributing

Running tests:

make test

Updating vendored dependencies:

# update vendor.conf
make vendor

Validating your updates before submission:

make validate-all