We scan this tool’s changelog a few times a day and keep the changes that would alter your agent’s next action: 8 since March 2026, each linked to its source.
buildkitWhen exporting a build result with the local or tar exporter, set `src` to the subdirectory to export; it must point to a directory within the build result.
buildctl build ... --output type=local,dest=<output-dir>,src=<build-result-subdirectory>When CI cannot inject command-line arguments, set `BUILDKITD_CONFIG` to the config file path and start `buildkitd`. An explicit `--config` flag takes precedence; if neither is set, the default path applies.
BUILDKITD_CONFIG=/etc/buildkit/custom.toml buildkitdWhen building with Dockerfile syntax 1.27.0, a zstd-compressed archive can be the build context or an `ADD` source. Use the archive as the context, or add its files with `ADD <archive> <destination>`; local tar archives unpack by default.
# syntax=docker.io/docker/dockerfile-upstream:1.27.0
FROM alpine
ADD <archive.tar.zst> /destination/When you need to inspect exec-step network requests or apply source policies to them, enable BuildKit proxy networking for the daemon or build, then review the build output. Use a source policy to allow, deny, or convert matching proxy-visible HTTP(S) GET URLs.
buildctl build --proxy-network --frontend dockerfile.v0 --local context=<context-dir> --local dockerfile=<dockerfile-dir>When exporting a build result to a local directory that should match the result, use `mode=delete` to remove destination files and directories absent from the result.
buildctl build ... --output type=local,dest=./bin/release,mode=deleteWhen building with a remote context or a stage timestamp, define `ARG SOURCE_DATE_EPOCH=context` or `ARG SOURCE_DATE_EPOCH=<stage>` to set the build timestamp from that source. Context resolution uses the Git commit time or, for HTTP contexts, `Last-Modified` or the newest TAR entry mtime when the header is absent.
ARG SOURCE_DATE_EPOCH=context
FROM alpineFor a remote build with a Git context, add `mtime=commit` to the Git URL query to set snapshot file, symlink, and directory mtimes to the resolved commit timestamp. If the Dockerfile frontend receives `SOURCE_DATE_EPOCH`, commit-time mtimes are selected automatically; the URL parameter can override the policy.
docker buildx build 'https://github.com/<owner>/<repo>.git?mtime=commit'When an LLB definition needs one raw blob from a container image registry or OCI layout, use the matching blob source. It downloads the blob as a single file into an empty snapshot.
blob := llb.ImageBlob("<registry>/<repository>@sha256:<digest>", llb.Filename("<filename>"))