ugit, but even smaller!

Dockerfile

FROM alpine:3.18 as base
ENV ESSENTIAL="tar sh"
ENV DEPS="ugit git fzf tput nl cut bash sed awk tr env xargs"

RUN apk add --no-cache \
    bash \
    coreutils \
    git \
    ncurses \
    ncurses-terminfo \
    curl \
    tar

# Download fzf binary from GitHub, pin to 0.46.0, ugit requires minimum 0.21.0
RUN curl -L -o fzf.tar.gz https://github.com/junegunn/fzf/releases/download/0.46.0/fzf-0.46.0-linux_amd64.tar.gz && \
    tar -xzf fzf.tar.gz && \
    mv fzf /usr/bin/

# Copy only the ugit script into the container at /app
COPY ugit .

# Set permissions and move the script to path
RUN chmod +x ugit && mv ugit /usr/bin/

# ldd all of ugit's dependencies and gzip them with tar
RUN mkdir /app; files=$(for file in $(which $DEPS $ESSENTIAL /bin/ls); do echo "$file" && ldd "$file"; done | \
      sed -E 's/ \(.*$//; s/^.* => //' | \
      tr -d ' \t' | \
      sort -u | tr '\n' ' '); \
      files="$files /usr/share/terminfo/x/xterm"; \
      tar -Phcvzf /app/app.tar.gz $files

# Use an intermediate stage to create the filesystem
FROM scratch AS app
COPY --from=base /app/app.tar.gz /app.tar.gz
COPY --from=base /lib/ld-musl-aarch64.so.1 /lib/ld-musl-aarch64.so.1
COPY --from=base /lib/libacl.so.1 /lib/libacl.so.1
COPY --from=base /bin/sh /bin/sh
COPY --from=base /usr/bin/tar /usr/bin/tar
COPY --from=base /bin/gzip /bin/gzip

# Finally, flatten everything into a single layer to improve
# download and decompression performance and untar on container start.
# Use $@ to accept arguments from `docker container create`
# Startup latency is minimal since the archive isn't very large
FROM scratch
COPY --from=app / /
ENV TERM=xterm
ENTRYPOINT [ "/bin/sh", \
             "-c", \
             "tar -Pxzf /app.tar.gz && /usr/bin/ugit $@" ]