ghrelgrab

Fetches and extracts a specified version of a GitHub release asset from a chosen repository for the current or mapped system architecture.

Usage

ghrelgrab \
  --repo owner/repo \
  --version v1.2.3 \
  --file "asset-{version}-{os}-{arch}.tar.gz"

Supported flags:

• --repo (required): GitHub owner/repo (e.g. owner/repo)
• --version (required): Release tag (e.g. v1.2.3)
• --file (required): Asset filename, supports {version}, {os}, and {arch} tokens
• --out: Output directory (default: current directory)
• --os: Override detected OS for {os} substitution (default: current OS)
• --os-map: Remap detected OS before substitution (e.g. linux=ubuntu,windows=win32)
• --arch: Override detected architecture for {arch} substitution (default: current arch)
• --arch-map: Remap detected arch before substitution (e.g. amd64=x86_64,arm64=aarch64)
• --token: GitHub token (defaults to GH_TOKEN env) for private assets
• --debug: Enable debug output

The tool automatically extracts .tar.gz, .tgz, and .zip archives. Other files are saved as-is. Output file paths are printed to stdout.

While this application can be used as a command line application, one of its uses is as a docker layer for downloading application dependencies.

# Stage 1: fetch the release asset with ghrelgrab 
FROM ghcr.io/unitvectory-labs/ghrelgrab:latest AS fetcher
WORKDIR /work

RUN ["/ghrelgrab","--repo","owner/repo","--version","v1.2.3","--file","asset-{version}-{os}-{arch}.tar.gz","--out","/work","--arch-map","x86_64=amd64,aarch64=arm64","--debug"]

# Stage 2: your runtime
FROM gcr.io/distroless/base-debian13

# If the tar extracts a file named `asset` at /work,
# copy it from there. Adjust the path if the archive has a subdir.
COPY --from=fetcher /work/asset /usr/local/bin/asset

WORKDIR /app

# the rest goes here...