Dockerfile

FROM debian:buster-slim

ARG KUBECTL_VERSION
# TARGETPLATFORM comes from the buildx context and it will be something like `linux/arm64/v8` or `linux/amd64`. Ref: https://docs.docker.com/buildx/working-with-buildx/
ARG TARGETPLATFORM

ENV PATH="/usr/bin:${PATH}"

RUN apt-get update \
    && apt-get install -y curl ca-certificates \
    && rm -rf /var/lib/apt/lists/*
RUN c_rehash

RUN  export arch=$(echo ${TARGETPLATFORM} | awk -F'/' '{print $2}') && \
     export url="https://dl.k8s.io/${KUBECTL_VERSION}/kubernetes-client-linux-${arch}.tar.gz" && \
     echo "Downloading ${url}" && \
     curl -L ${url} > /tmp/kubectl.tar.gz && \
     # kubectl is inside /kubernetes/client/bin in the archive, so we trim 3 elements in the path
     tar -xzvf /tmp/kubectl.tar.gz --strip-components=3 --directory /usr/bin && \
    rm /tmp/kubectl.tar.gz
ENTRYPOINT ["kubectl"]