mirror of https://github.com/docker/cli.git
495 lines
19 KiB
Markdown
495 lines
19 KiB
Markdown
[](https://asciinema.org/a/gPEIEo1NzmDTUu2bEPsUboqmU)
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# BuildKit
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[](https://godoc.org/github.com/moby/buildkit/client/llb)
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[](https://travis-ci.org/moby/buildkit)
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[](https://goreportcard.com/report/github.com/moby/buildkit)
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BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner.
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Key features:
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- Automatic garbage collection
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- Extendable frontend formats
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- Concurrent dependency resolution
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- Efficient instruction caching
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- Build cache import/export
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- Nested build job invocations
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- Distributable workers
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- Multiple output formats
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- Pluggable architecture
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- Execution without root privileges
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Read the proposal from https://github.com/moby/moby/issues/32925
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Introductory blog post https://blog.mobyproject.org/introducing-buildkit-17e056cc5317
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Join `#buildkit` channel on [Docker Community Slack](http://dockr.ly/slack)
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:information_source: If you are visiting this repo for the usage of experimental Dockerfile features like `RUN --mount=type=(bind|cache|tmpfs|secret|ssh)`, please refer to [`frontend/dockerfile/docs/experimental.md`](frontend/dockerfile/docs/experimental.md).
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:information_source: [BuildKit has been integrated to `docker build` since Docker 18.06 .](https://docs.docker.com/develop/develop-images/build_enhancements/)
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You don't need to read this document unless you want to use the full-featured standalone version of BuildKit.
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<!-- START doctoc generated TOC please keep comment here to allow auto update -->
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<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
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- [Used by](#used-by)
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- [Quick start](#quick-start)
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- [Starting the `buildkitd` daemon:](#starting-the-buildkitd-daemon)
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- [Exploring LLB](#exploring-llb)
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- [Exploring Dockerfiles](#exploring-dockerfiles)
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- [Building a Dockerfile with `buildctl`](#building-a-dockerfile-with-buildctl)
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- [Building a Dockerfile using external frontend:](#building-a-dockerfile-using-external-frontend)
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- [Building a Dockerfile with experimental features like `RUN --mount=type=(bind|cache|tmpfs|secret|ssh)`](#building-a-dockerfile-with-experimental-features-like-run---mounttypebindcachetmpfssecretssh)
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- [Output](#output)
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- [Image/Registry](#imageregistry)
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- [Local directory](#local-directory)
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- [Docker tarball](#docker-tarball)
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- [OCI tarball](#oci-tarball)
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- [containerd image store](#containerd-image-store)
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- [Cache](#cache)
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- [Garbage collection](#garbage-collection)
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- [Export cache](#export-cache)
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- [Inline (push image and cache together)](#inline-push-image-and-cache-together)
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- [Registry (push image and cache separately)](#registry-push-image-and-cache-separately)
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- [Local directory](#local-directory-1)
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- [`--export-cache` options](#--export-cache-options)
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- [`--import-cache` options](#--import-cache-options)
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- [Consistent hashing](#consistent-hashing)
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- [Expose BuildKit as a TCP service](#expose-buildkit-as-a-tcp-service)
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- [Load balancing](#load-balancing)
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- [Containerizing BuildKit](#containerizing-buildkit)
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- [Podman](#podman)
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- [Kubernetes](#kubernetes)
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- [Daemonless](#daemonless)
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- [Opentracing support](#opentracing-support)
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- [Running BuildKit without root privileges](#running-buildkit-without-root-privileges)
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- [Building multi-platform images](#building-multi-platform-images)
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- [Contributing](#contributing)
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<!-- END doctoc generated TOC please keep comment here to allow auto update -->
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## Used by
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BuildKit is used by the following projects:
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- [Moby & Docker](https://github.com/moby/moby/pull/37151) (`DOCKER_BUILDKIT=1 docker build`)
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- [img](https://github.com/genuinetools/img)
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- [OpenFaaS Cloud](https://github.com/openfaas/openfaas-cloud)
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- [container build interface](https://github.com/containerbuilding/cbi)
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- [Tekton Pipelines](https://github.com/tektoncd/catalog) (formerly [Knative Build Templates](https://github.com/knative/build-templates))
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- [the Sanic build tool](https://github.com/distributed-containers-inc/sanic)
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- [vab](https://github.com/stellarproject/vab)
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- [Rio](https://github.com/rancher/rio)
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- [PouchContainer](https://github.com/alibaba/pouch)
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- [Docker buildx](https://github.com/docker/buildx)
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- [Okteto Cloud](https://okteto.com/)
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- [Earthly earthfiles](https://github.com/vladaionescu/earthly)
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## Quick start
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:information_source: For Kubernetes deployments, see [`examples/kubernetes`](./examples/kubernetes).
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BuildKit is composed of the `buildkitd` daemon and the `buildctl` client.
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While the `buildctl` client is available for Linux, macOS, and Windows, the `buildkitd` daemon is only available for Linux currently.
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The `buildkitd` daemon requires the following components to be installed:
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- [runc](https://github.com/opencontainers/runc) or [crun](https://github.com/containers/crun)
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- [containerd](https://github.com/containerd/containerd) (if you want to use containerd worker)
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The latest binaries of BuildKit are available [here](https://github.com/moby/buildkit/releases) for Linux, macOS, and Windows.
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[Homebrew package](https://formulae.brew.sh/formula/buildkit) (unofficial) is available for macOS.
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```console
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$ brew install buildkit
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```
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To build BuildKit from source, see [`.github/CONTRIBUTING.md`](./.github/CONTRIBUTING.md).
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### Starting the `buildkitd` daemon:
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You need to run `buildkitd` as the root user on the host.
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```bash
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$ sudo buildkitd
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```
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To run `buildkitd` as a non-root user, see [`docs/rootless.md`](docs/rootless.md).
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The buildkitd daemon supports two worker backends: OCI (runc) and containerd.
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By default, the OCI (runc) worker is used. You can set `--oci-worker=false --containerd-worker=true` to use the containerd worker.
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We are open to adding more backends.
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The buildkitd daemon listens gRPC API on `/run/buildkit/buildkitd.sock` by default, but you can also use TCP sockets.
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See [Expose BuildKit as a TCP service](#expose-buildkit-as-a-tcp-service).
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### Exploring LLB
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BuildKit builds are based on a binary intermediate format called LLB that is used for defining the dependency graph for processes running part of your build. tl;dr: LLB is to Dockerfile what LLVM IR is to C.
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- Marshaled as Protobuf messages
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- Concurrently executable
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- Efficiently cacheable
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- Vendor-neutral (i.e. non-Dockerfile languages can be easily implemented)
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See [`solver/pb/ops.proto`](./solver/pb/ops.proto) for the format definition, and see [`./examples/README.md`](./examples/README.md) for example LLB applications.
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Currently, the following high-level languages has been implemented for LLB:
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- Dockerfile (See [Exploring Dockerfiles](#exploring-dockerfiles))
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- [Buildpacks](https://github.com/tonistiigi/buildkit-pack)
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- [Mockerfile](https://matt-rickard.com/building-a-new-dockerfile-frontend/)
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- [Gockerfile](https://github.com/po3rin/gockerfile)
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- [bldr (Pkgfile)](https://github.com/talos-systems/bldr/)
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- [HLB](https://github.com/openllb/hlb)
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- [Earthfile (Earthly)](https://github.com/earthly/earthly)
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- [Cargo Wharf (Rust)](https://github.com/denzp/cargo-wharf)
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- (open a PR to add your own language)
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### Exploring Dockerfiles
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Frontends are components that run inside BuildKit and convert any build definition to LLB. There is a special frontend called gateway (`gateway.v0`) that allows using any image as a frontend.
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During development, Dockerfile frontend (`dockerfile.v0`) is also part of the BuildKit repo. In the future, this will be moved out, and Dockerfiles can be built using an external image.
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#### Building a Dockerfile with `buildctl`
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```bash
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buildctl build \
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--frontend=dockerfile.v0 \
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--local context=. \
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--local dockerfile=.
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# or
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buildctl build \
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--frontend=dockerfile.v0 \
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--local context=. \
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--local dockerfile=. \
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--opt target=foo \
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--opt build-arg:foo=bar
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```
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`--local` exposes local source files from client to the builder. `context` and `dockerfile` are the names Dockerfile frontend looks for build context and Dockerfile location.
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#### Building a Dockerfile using external frontend:
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External versions of the Dockerfile frontend are pushed to https://hub.docker.com/r/docker/dockerfile-upstream and https://hub.docker.com/r/docker/dockerfile and can be used with the gateway frontend. The source for the external frontend is currently located in `./frontend/dockerfile/cmd/dockerfile-frontend` but will move out of this repository in the future ([#163](https://github.com/moby/buildkit/issues/163)). For automatic build from master branch of this repository `docker/dockerfile-upsteam:master` or `docker/dockerfile-upstream:master-experimental` image can be used.
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```bash
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buildctl build \
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--frontend gateway.v0 \
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--opt source=docker/dockerfile \
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--local context=. \
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--local dockerfile=.
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buildctl build \
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--frontend gateway.v0 \
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--opt source=docker/dockerfile \
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--opt context=git://github.com/moby/moby \
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--opt build-arg:APT_MIRROR=cdn-fastly.deb.debian.org
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```
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#### Building a Dockerfile with experimental features like `RUN --mount=type=(bind|cache|tmpfs|secret|ssh)`
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See [`frontend/dockerfile/docs/experimental.md`](frontend/dockerfile/docs/experimental.md).
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### Output
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By default, the build result and intermediate cache will only remain internally in BuildKit. An output needs to be specified to retrieve the result.
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#### Image/Registry
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```bash
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buildctl build ... --output type=image,name=docker.io/username/image,push=true
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```
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To export the cache embed with the image and pushing them to registry together, type `registry` is required to import the cache, you should specify `--export-cache type=inline` and `--import-cache type=registry,ref=...`. To export the cache to a local directy, you should specify `--export-cache type=local`.
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Details in [Export cache](#export-cache).
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```bash
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buildctl build ...\
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--output type=image,name=docker.io/username/image,push=true \
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--export-cache type=inline \
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--import-cache type=registry,ref=docker.io/username/image
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```
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Keys supported by image output:
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* `name=[value]`: image name
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* `push=true`: push after creating the image
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* `push-by-digest=true`: push unnamed image
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* `registry.insecure=true`: push to insecure HTTP registry
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* `oci-mediatypes=true`: use OCI mediatypes in configuration JSON instead of Docker's
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* `unpack=true`: unpack image after creation (for use with containerd)
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* `dangling-name-prefix=[value]`: name image with `prefix@<digest>` , used for anonymous images
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* `name-canonical=true`: add additional canonical name `name@<digest>`
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* `compression=[uncompressed,gzip]`: choose compression type for layer, gzip is default value
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If credentials are required, `buildctl` will attempt to read Docker configuration file `$DOCKER_CONFIG/config.json`.
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`$DOCKER_CONFIG` defaults to `~/.docker`.
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#### Local directory
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The local client will copy the files directly to the client. This is useful if BuildKit is being used for building something else than container images.
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```bash
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buildctl build ... --output type=local,dest=path/to/output-dir
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```
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To export specific files use multi-stage builds with a scratch stage and copy the needed files into that stage with `COPY --from`.
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```dockerfile
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...
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FROM scratch as testresult
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COPY --from=builder /usr/src/app/testresult.xml .
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...
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```
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```bash
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buildctl build ... --opt target=testresult --output type=local,dest=path/to/output-dir
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```
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Tar exporter is similar to local exporter but transfers the files through a tarball.
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```bash
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buildctl build ... --output type=tar,dest=out.tar
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buildctl build ... --output type=tar > out.tar
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```
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#### Docker tarball
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```bash
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# exported tarball is also compatible with OCI spec
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buildctl build ... --output type=docker,name=myimage | docker load
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```
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#### OCI tarball
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```bash
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buildctl build ... --output type=oci,dest=path/to/output.tar
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buildctl build ... --output type=oci > output.tar
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```
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#### containerd image store
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The containerd worker needs to be used
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```bash
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buildctl build ... --output type=image,name=docker.io/username/image
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ctr --namespace=buildkit images ls
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```
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To change the containerd namespace, you need to change `worker.containerd.namespace` in [`/etc/buildkit/buildkitd.toml`](./docs/buildkitd.toml.md).
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## Cache
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To show local build cache (`/var/lib/buildkit`):
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```bash
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buildctl du -v
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```
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To prune local build cache:
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```bash
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buildctl prune
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```
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### Garbage collection
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See [`./docs/buildkitd.toml.md`](./docs/buildkitd.toml.md).
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### Export cache
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BuildKit supports the following cache exporters:
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* `inline`: embed the cache into the image, and push them to the registry together
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* `registry`: push the image and the cache separately
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* `local`: export to a local directory
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In most case you want to use the `inline` cache exporter.
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However, note that the `inline` cache exporter only supports `min` cache mode.
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To enable `max` cache mode, push the image and the cache separately by using `registry` cache exporter.
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#### Inline (push image and cache together)
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```bash
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buildctl build ... \
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--output type=image,name=docker.io/username/image,push=true \
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--export-cache type=inline \
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--import-cache type=registry,ref=docker.io/username/image
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```
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Note that the inline cache is not imported unless `--import-cache type=registry,ref=...` is provided.
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:information_source: Docker-integrated BuildKit (`DOCKER_BUILDKIT=1 docker build`) and `docker buildx`requires
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`--build-arg BUILDKIT_INLINE_CACHE=1` to be specified to enable the `inline` cache exporter.
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However, the standalone `buildctl` does NOT require `--opt build-arg:BUILDKIT_INLINE_CACHE=1` and the build-arg is simply ignored.
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#### Registry (push image and cache separately)
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```bash
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buildctl build ... \
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--output type=image,name=localhost:5000/myrepo:image,push=true \
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--export-cache type=registry,ref=localhost:5000/myrepo:buildcache \
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--import-cache type=registry,ref=localhost:5000/myrepo:buildcache \
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```
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#### Local directory
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```bash
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buildctl build ... --export-cache type=local,dest=path/to/output-dir
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buildctl build ... --import-cache type=local,src=path/to/input-dir
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```
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The directory layout conforms to OCI Image Spec v1.0.
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#### `--export-cache` options
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- `type`: `inline`, `registry`, or `local`
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- `mode=min` (default): only export layers for the resulting image
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- `mode=max`: export all the layers of all intermediate steps. Not supported for `inline` cache exporter.
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- `ref=docker.io/user/image:tag`: reference for `registry` cache exporter
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- `dest=path/to/output-dir`: directory for `local` cache exporter
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- `oci-mediatypes=true|false`: whether to use OCI mediatypes in exported manifests for `local` and `registry` exporter. Since BuildKit `v0.8` defaults to true.
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#### `--import-cache` options
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- `type`: `registry` or `local`. Use `registry` to import `inline` cache.
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- `ref=docker.io/user/image:tag`: reference for `registry` cache importer
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- `src=path/to/input-dir`: directory for `local` cache importer
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- `digest=sha256:deadbeef`: digest of the manifest list to import for `local` cache importer.
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- `tag=customtag`: custom tag of image for `local` cache importer.
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Defaults to the digest of "latest" tag in `index.json` is for digest, not for tag
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### Consistent hashing
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If you have multiple BuildKit daemon instances but you don't want to use registry for sharing cache across the cluster,
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consider client-side load balancing using consistent hashing.
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See [`./examples/kubernetes/consistenthash`](./examples/kubernetes/consistenthash).
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## Expose BuildKit as a TCP service
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The `buildkitd` daemon can listen the gRPC API on a TCP socket.
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It is highly recommended to create TLS certificates for both the daemon and the client (mTLS).
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Enabling TCP without mTLS is dangerous because the executor containers (aka Dockerfile `RUN` containers) can call BuildKit API as well.
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```bash
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buildkitd \
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--addr tcp://0.0.0.0:1234 \
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--tlscacert /path/to/ca.pem \
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--tlscert /path/to/cert.pem \
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--tlskey /path/to/key.pem
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```
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```bash
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buildctl \
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--addr tcp://example.com:1234 \
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--tlscacert /path/to/ca.pem \
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--tlscert /path/to/clientcert.pem \
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--tlskey /path/to/clientkey.pem \
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build ...
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```
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### Load balancing
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`buildctl build` can be called against randomly load balanced the `buildkitd` daemon.
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See also [Consistent hashing](#consistenthashing) for client-side load balancing.
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## Containerizing BuildKit
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BuildKit can also be used by running the `buildkitd` daemon inside a Docker container and accessing it remotely.
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We provide the container images as [`moby/buildkit`](https://hub.docker.com/r/moby/buildkit/tags/):
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- `moby/buildkit:latest`: built from the latest regular [release](https://github.com/moby/buildkit/releases)
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- `moby/buildkit:rootless`: same as `latest` but runs as an unprivileged user, see [`docs/rootless.md`](docs/rootless.md)
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- `moby/buildkit:master`: built from the master branch
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- `moby/buildkit:master-rootless`: same as master but runs as an unprivileged user, see [`docs/rootless.md`](docs/rootless.md)
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To run daemon in a container:
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```bash
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docker run -d --name buildkitd --privileged moby/buildkit:latest
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export BUILDKIT_HOST=docker-container://buildkitd
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buildctl build --help
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```
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### Podman
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To connect to a BuildKit daemon running in a Podman container, use `podman-container://` instead of `docker-container://` .
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```bash
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podman run -d --name buildkitd --privileged moby/buildkit:latest
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buildctl --addr=podman-container://buildkitd build --frontend dockerfile.v0 --local context=. --local dockerfile=. --output type=oci | podman load foo
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```
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`sudo` is not required.
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### Kubernetes
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For Kubernetes deployments, see [`examples/kubernetes`](./examples/kubernetes).
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### Daemonless
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To run client and an ephemeral daemon in a single container ("daemonless mode"):
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```bash
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docker run \
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-it \
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--rm \
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--privileged \
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-v /path/to/dir:/tmp/work \
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--entrypoint buildctl-daemonless.sh \
|
|
moby/buildkit:master \
|
|
build \
|
|
--frontend dockerfile.v0 \
|
|
--local context=/tmp/work \
|
|
--local dockerfile=/tmp/work
|
|
```
|
|
|
|
or
|
|
|
|
```bash
|
|
docker run \
|
|
-it \
|
|
--rm \
|
|
--security-opt seccomp=unconfined \
|
|
--security-opt apparmor=unconfined \
|
|
-e BUILDKITD_FLAGS=--oci-worker-no-process-sandbox \
|
|
-v /path/to/dir:/tmp/work \
|
|
--entrypoint buildctl-daemonless.sh \
|
|
moby/buildkit:master-rootless \
|
|
build \
|
|
--frontend \
|
|
dockerfile.v0 \
|
|
--local context=/tmp/work \
|
|
--local dockerfile=/tmp/work
|
|
```
|
|
|
|
## Opentracing support
|
|
|
|
BuildKit supports opentracing for buildkitd gRPC API and buildctl commands. To capture the trace to [Jaeger](https://github.com/jaegertracing/jaeger), set `JAEGER_TRACE` environment variable to the collection address.
|
|
|
|
```bash
|
|
docker run -d -p6831:6831/udp -p16686:16686 jaegertracing/all-in-one:latest
|
|
export JAEGER_TRACE=0.0.0.0:6831
|
|
# restart buildkitd and buildctl so they know JAEGER_TRACE
|
|
# any buildctl command should be traced to http://127.0.0.1:16686/
|
|
```
|
|
|
|
## Running BuildKit without root privileges
|
|
|
|
Please refer to [`docs/rootless.md`](docs/rootless.md).
|
|
|
|
## Building multi-platform images
|
|
|
|
See [`docker buildx` documentation](https://github.com/docker/buildx#building-multi-platform-images)
|
|
|
|
## Contributing
|
|
|
|
Want to contribute to BuildKit? Awesome! You can find information about contributing to this project in the [CONTRIBUTING.md](/.github/CONTRIBUTING.md)
|
|
|