ci: Use DOCKER_BUILDKIT for lint image

Can be reviewed with:
--color-moved=dimmed-zebra  --ignore-all-space

.cirrus.yml

@@ -70,7 +70,7 @@ task:
   # For faster CI feedback, immediately schedule the linters
   << : *CREDITS_TEMPLATE
   python_cache:
-    folder: "/tmp/python"
+    folder: "/python_build"
     fingerprint_script: cat .python-version /etc/os-release
   unshallow_script:
     - git fetch --unshallow --no-tags

.python-version

@@ -1 +1 @@
-3.8.16
+3.8.17

ci/lint/04_install.sh

@@ -13,32 +13,31 @@ ${CI_RETRY_EXE} apt-get update
 # - gpg (used by verify-commits)
 ${CI_RETRY_EXE} apt-get install -y curl xz-utils git gpg
 
-if [ -z "${SKIP_PYTHON_INSTALL}" ]; then
-    PYTHON_PATH=/tmp/python
-    if [ ! -d "${PYTHON_PATH}/bin" ]; then
-      (
-        git clone https://github.com/pyenv/pyenv.git
-        cd pyenv/plugins/python-build || exit 1
-        ./install.sh
-      )
-      # For dependencies see https://github.com/pyenv/pyenv/wiki#suggested-build-environment
-      ${CI_RETRY_EXE} apt-get install -y build-essential libssl-dev zlib1g-dev \
-        libbz2-dev libreadline-dev libsqlite3-dev curl llvm \
-        libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev \
-        clang
-      env CC=clang python-build "$(cat "${BASE_ROOT_DIR}/.python-version")" "${PYTHON_PATH}"
-    fi
-    export PATH="${PYTHON_PATH}/bin:${PATH}"
-    command -v python3
-    python3 --version
+PYTHON_PATH="/python_build"
+if [ ! -d "${PYTHON_PATH}/bin" ]; then
+  (
+    git clone https://github.com/pyenv/pyenv.git
+    cd pyenv/plugins/python-build || exit 1
+    ./install.sh
+  )
+  # For dependencies see https://github.com/pyenv/pyenv/wiki#suggested-build-environment
+  ${CI_RETRY_EXE} apt-get install -y build-essential libssl-dev zlib1g-dev \
+    libbz2-dev libreadline-dev libsqlite3-dev curl llvm \
+    libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev \
+    clang
+  env CC=clang python-build "$(cat "./.python-version")" "${PYTHON_PATH}"
 fi
+export PATH="${PYTHON_PATH}/bin:${PATH}"
+command -v python3
+python3 --version
 
-${CI_RETRY_EXE} pip3 install codespell==2.2.5
-${CI_RETRY_EXE} pip3 install flake8==6.0.0
-${CI_RETRY_EXE} pip3 install lief==0.13.2
-${CI_RETRY_EXE} pip3 install mypy==1.4.1
-${CI_RETRY_EXE} pip3 install pyzmq==25.1.0
-${CI_RETRY_EXE} pip3 install vulture==2.6
+${CI_RETRY_EXE} pip3 install \
+  codespell==2.2.5 \
+  flake8==6.0.0 \
+  lief==0.13.2 \
+  mypy==1.4.1 \
+  pyzmq==25.1.0 \
+  vulture==2.6
 
 SHELLCHECK_VERSION=v0.8.0
 curl -sL "https://github.com/koalaman/shellcheck/releases/download/${SHELLCHECK_VERSION}/shellcheck-${SHELLCHECK_VERSION}.linux.x86_64.tar.xz" | \

ci/lint/docker-entrypoint.sh

@@ -5,6 +5,8 @@ export LC_ALL=C
 # of the mounted bitcoin src dir.
 git config --global --add safe.directory /bitcoin
 
+export PATH="/python_build/bin:${PATH}"
+
 if [ -z "$1" ]; then
   LOCAL_BRANCH=1 bash -ic "./ci/lint/06_script.sh"
 else

ci/lint_imagefile

@@ -0,0 +1,19 @@
+# See test/lint/README.md for usage.
+
+FROM debian:bookworm
+
+ENV DEBIAN_FRONTEND=noninteractive
+ENV LC_ALL=C.UTF-8
+
+COPY ./.python-version /.python-version
+COPY ./ci/lint/docker-entrypoint.sh /entrypoint.sh
+COPY ./ci/lint/04_install.sh /install.sh
+
+RUN /install.sh && \
+  echo 'alias lint="./ci/lint/06_script.sh"' >> ~/.bashrc && \
+  chmod 755 /entrypoint.sh && \
+  rm -rf /var/lib/apt/lists/*
+
+
+WORKDIR /bitcoin
+ENTRYPOINT ["/entrypoint.sh"]

test/lint/README.md

@@ -7,10 +7,8 @@ To run linters locally with the same versions as the CI environment, use the inc
 Dockerfile:
 
 ```sh
-cd ./ci/lint
-docker build -t bitcoin-linter .
+DOCKER_BUILDKIT=1 docker build -t bitcoin-linter --file "./ci/lint_imagefile" ./
 
-cd /root/of/bitcoin/repo
 docker run --rm -v $(pwd):/bitcoin -it bitcoin-linter
 ```