Overview

Some demos for exploring buildkitd.

Demo

Dependencies

• Golang: https://go.dev/dl/
• Docker: https://docs.docker.com/
• Image: https://hub.docker.com/r/moby/buildkit
• CLI:
  • buildctl: https://github.com/moby/buildkit
  • jq: https://stedolan.github.io/jq/

hardcode-image

The demo hardcodes LLB to understand how Frontends converts image source to LLB.

Get json formatted LLB:

$ go run cmd/hardcode-image/main.go | buildctl debug dump-llb | jq .

Build:

$ docker run -d --name buildkitd --privileged moby/buildkit:v0.10.3
$ export BUILDKIT_HOST=docker-container://buildkitd
$ go run cmd/hardcode-image/main.go | buildctl build --local context=. --output type=tar,dest=out.tar

You can unpack out.tar and find README.md and built.txt files which are operated in the program.

You can also modify the output type to build the type that buildkitd supports: Output.

hardcode-scratch

The demo hardcodes LLB to understand how Frontends converts scratch source to LLB.

Get json formatted LLB:

$ go run cmd/hardcode-scratch/main.go | buildctl debug dump-llb | jq .

Build:

$ docker run -d --name buildkitd --privileged moby/buildkit:v0.10.3
$ export BUILDKIT_HOST=docker-container://buildkitd
$ go run cmd/hardcode-scratch/main.go | buildctl build --local context=. --output type=tar,dest=out.tar

You can unpack out.tar and find copied files which are operated in the program.

You can also get a feel for buildkitd's parallel builds and caching by looking at the execution.

Note:

• I don't understand the internals yet -_-

frontend-mockerfile

This demo uses other people's examples to see how buildkitd frontend is implemented: detail.

Get json formatted LLB:

$ go run cmd/frontend-mockerfile/main.go -filename cmd/frontend-mockerfile/Mockerfile.yaml -graph | buildctl debug dump-llb | jq .

Build:

# You should change image registry in the following script.
$ ./build/build-frontend-mockerfile.sh

# PUSH IMAGE THAT IS BUILT ABOVE.
$ docker push <IMAGE/BUILT/ABOVE>

# Image Example: `ccr.ccs.tencentyun.com/flyer103/frontend-mocker:latest`
$ buildctl build --frontend=gateway.v0 --opt source=<IMAGE/BUILT/ABOVE> --local context=. --local dockerfile=./yaml/frontend-mockerfile/ --output type=oci,dest=output.tar

If you add # syntax=ccr.ccs.tencentyun.com/flyer103/frontend-mocker:latest to the first line of yaml/frontend-mockerfile/Mockerfile.yaml, you could also use docker build as following:

$ docker build . -t demo:0.1 -f yaml/frontend-mockerfile/Mockerfile.yaml

Note:

• syntax directive in the yaml file is not a must if we use buildctl