feat: add debian:13-slim runner image for Gitea Actions

Self-contained Dockerfile under linux/debian/ that bakes runner user,
Docker CE, Node.js v20+v24, latest Go, yq, and act env vars. Uses
Debian's git-lfs and Docker CE from download.docker.com. Published to
git.ipng.ch/ipng/gitea-debian-runner:13-slim. README documents build
and push commands (single-arch and multi-arch via buildx).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -66,6 +66,47 @@
   - `ghcr.io/catthehacker/ubuntu:custom-24.04`
   - `ghcr.io/catthehacker/ubuntu:custom-latest`
 
+## IPng Debian Runner
+
+A `debian:13-slim`-based variant of the `act`/`runner` image, intended for use with Gitea Actions. Compared to the Ubuntu images it adds `rsync`, ships `git-lfs` from Debian's archive (rather than the packagecloud repo), and uses Docker CE from `download.docker.com` instead of Microsoft's moby builds.
+
+Source: [`linux/debian/Dockerfile`](./linux/debian/Dockerfile). It is a single self-contained Dockerfile (no helper scripts) and bakes the `runner` user, Docker CE, Node.js LTS (v20 + v24), the latest stable Go release from go.dev, `yq`, and the `act`/runner environment variables (`ImageOS=debian13`, tool cache paths, etc.).
+
+Published to `git.ipng.ch/ipng/gitea-debian-runner:13-slim`.
+
+### Build
+
+```sh
+docker build --load \
+  --file linux/debian/Dockerfile \
+  --tag git.ipng.ch/ipng/gitea-debian-runner:13-slim \
+  --build-arg BUILD_DATE="$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
+  --build-arg BUILD_REF="$(git rev-parse HEAD)" \
+  .
+```
+
+`--load` makes the image available to the local docker daemon — required when buildx uses the `docker-container` driver (the default on multi-platform setups).
+
+For multi-arch (amd64 + arm64) using buildx, building and pushing in one step:
+
+```sh
+docker buildx build \
+  --file linux/debian/Dockerfile \
+  --platform linux/amd64,linux/arm64 \
+  --tag git.ipng.ch/ipng/gitea-debian-runner:13-slim \
+  --build-arg BUILD_DATE="$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
+  --build-arg BUILD_REF="$(git rev-parse HEAD)" \
+  --push \
+  .
+```
+
+### Push (single-arch)
+
+```sh
+docker login git.ipng.ch
+docker push git.ipng.ch/ipng/gitea-debian-runner:13-slim
+```
+
 ## [`ubuntu-20.04` has been deprecated and images for that environment will not be updated anymore](https://github.com/actions/runner-images/pull/11748)
 
 ## [`ubuntu-18.04` has been deprecated and images for that environment will not be updated anymore](https://github.com/actions/runner-images/issues/6002)

linux/debian/Dockerfile

@@ -0,0 +1,160 @@
+FROM debian:13-slim
+
+ARG TARGETARCH
+ARG NODE_VERSION="20 24"
+ARG RUNNER=runner
+ARG BUILD_DATE
+ARG BUILD_REF
+ARG BUILD_TAG=gitea-debian-runner
+ARG BUILD_TAG_VERSION=13-slim
+ARG BUILD_OWNER=ipng
+ARG BUILD_REPO=gitea-debian-runner
+
+ENV DEBIAN_FRONTEND=noninteractive \
+    ImageOS=debian13 \
+    IMAGE_OS=debian13 \
+    LSB_RELEASE=13 \
+    LSB_OS_VERSION=13 \
+    AGENT_TOOLSDIRECTORY=/opt/hostedtoolcache \
+    RUN_TOOL_CACHE=/opt/hostedtoolcache \
+    ACT_TOOLSDIRECTORY=/opt/acttoolcache \
+    DEPLOYMENT_BASEPATH=/opt/runner \
+    RUNNER_TEMP=/home/runner/work/_temp \
+    USER=runner \
+    RUNNER_USER=runner \
+    PATH=/home/runner/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+
+SHELL ["/bin/bash", "--login", "-eo", "pipefail", "-c"]
+WORKDIR /tmp
+
+RUN <<'EOF'
+set -Eeuxo pipefail
+
+node_arch() {
+  case "$(uname -m)" in
+    aarch64) echo arm64 ;;
+    x86_64)  echo x64 ;;
+    armv7l)  echo armv7l ;;
+    *) exit 1 ;;
+  esac
+}
+yq_arch() {
+  case "$(uname -m)" in
+    aarch64) echo arm64 ;;
+    x86_64)  echo amd64 ;;
+    armv7l)  echo arm ;;
+    *) exit 1 ;;
+  esac
+}
+go_arch() {
+  case "$(uname -m)" in
+    aarch64) echo arm64 ;;
+    x86_64)  echo amd64 ;;
+    armv7l)  echo armv6l ;;
+    *) exit 1 ;;
+  esac
+}
+
+apt-get -yq update
+apt-get -yq install --no-install-recommends \
+  ca-certificates curl wget gnupg ssh sudo gawk jq \
+  zstd zip unzip xz-utils \
+  git git-lfs rsync \
+  python3-pip python3-venv pipx \
+  libyaml-0-2
+
+ln -sf "$(command -v python3)" /usr/local/bin/python
+git config --system --add safe.directory '*'
+
+install -m 0755 -d /etc/apt/keyrings
+curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
+chmod a+r /etc/apt/keyrings/docker.asc
+. /etc/os-release
+echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian ${VERSION_CODENAME} stable" \
+  > /etc/apt/sources.list.d/docker.list
+apt-get -yq update
+apt-get -yq install --no-install-recommends \
+  docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
+
+mkdir -m 0700 -p /root/.ssh
+{ ssh-keyscan github.com; ssh-keyscan ssh.dev.azure.com; } >> /etc/ssh/ssh_known_hosts
+
+sed -i 's|"||g' /etc/environment
+{
+  echo "ImageOS=${ImageOS}"
+  echo "IMAGE_OS=${IMAGE_OS}"
+  echo "LSB_RELEASE=${LSB_RELEASE}"
+  echo "LSB_OS_VERSION=${LSB_OS_VERSION}"
+  echo "AGENT_TOOLSDIRECTORY=${AGENT_TOOLSDIRECTORY}"
+  echo "RUN_TOOL_CACHE=${RUN_TOOL_CACHE}"
+  echo "ACT_TOOLSDIRECTORY=${ACT_TOOLSDIRECTORY}"
+  echo "DEPLOYMENT_BASEPATH=${DEPLOYMENT_BASEPATH}"
+  echo "USER=${USER}"
+  echo "RUNNER_USER=${RUNNER_USER}"
+  echo "RUNNER_TEMP=${RUNNER_TEMP}"
+} >> /etc/environment
+
+mkdir -m 0777 -p "${AGENT_TOOLSDIRECTORY}" "${ACT_TOOLSDIRECTORY}" /github
+
+IFS=' ' read -r -a NODE <<<"${NODE_VERSION}"
+for ver in "${NODE[@]}"; do
+  if [[ "${ver}" == "24" && "$(node_arch)" == "armv7l" ]]; then
+    ver=22
+  fi
+  VER=$(curl -fsSL https://nodejs.org/download/release/index.json \
+    | jq -r "[.[] | select(.version|test(\"^v${ver}\\\\.\"))][0].version")
+  NODEPATH="${ACT_TOOLSDIRECTORY}/node/${VER:1}/$(node_arch)"
+  mkdir -m 0777 -p "${NODEPATH}"
+  wget -q "https://nodejs.org/download/release/latest-v${ver}.x/node-${VER}-linux-$(node_arch).tar.xz" -O node.tar.xz
+  tar -Jxf node.tar.xz --strip-components=1 -C "${NODEPATH}"
+  rm node.tar.xz
+  if [[ "${ver}" == "24" || ( "${ver}" == "22" && "$(node_arch)" == "armv7l" ) ]]; then
+    ln -sfn "${NODEPATH}" "${ACT_TOOLSDIRECTORY}/node/current"
+    ln -sf "${NODEPATH}"/bin/node "${NODEPATH}"/bin/npm "${NODEPATH}"/bin/npx "${NODEPATH}"/bin/corepack /usr/local/bin/
+  fi
+done
+
+base_url=https://github.com/mikefarah/yq/releases/latest/download
+wget -q "${base_url}/yq_linux_$(yq_arch)" -O /usr/bin/yq
+chmod +x /usr/bin/yq
+
+GO_VER=$(curl -fsSL 'https://go.dev/dl/?mode=json' | jq -r '.[0].version' | sed 's/^go//')
+GO_PATH="${ACT_TOOLSDIRECTORY}/go/${GO_VER}/$(go_arch)"
+mkdir -m 0777 -p "${GO_PATH}"
+wget -qO- "https://go.dev/dl/go${GO_VER}.linux-$(go_arch).tar.gz" | tar -zxf - --strip-components=1 -C "${GO_PATH}"
+touch "${GO_PATH}.complete"
+ln -sf "${GO_PATH}"/bin/* /usr/local/bin/
+
+groupadd -g 1001 "${RUNNER}"
+RUNNERADMIN="${RUNNER}admin"
+groupadd -g 1000 "${RUNNERADMIN}" || RUNNERADMIN="$(id -gn 1000)"
+useradd  -u 1001 -g "${RUNNER}" -G sudo -m -s /bin/bash "${RUNNER}"
+useradd  -u 1000 -g "${RUNNERADMIN}" -G sudo -m -s /bin/bash "${RUNNERADMIN}" || true
+usermod -aG docker "${RUNNER}"
+usermod -aG docker "${RUNNERADMIN}"
+{
+  echo "${RUNNER} ALL=(ALL) NOPASSWD: ALL"
+  echo "${RUNNERADMIN} ALL=(ALL) NOPASSWD: ALL"
+} >> /etc/sudoers
+
+mkdir -p "/home/${RUNNER}/work/_temp"
+mkdir -m 0700 -p "/home/${RUNNER}/.ssh"
+{ ssh-keyscan -t rsa github.com; ssh-keyscan -t rsa ssh.dev.azure.com; } > "/home/${RUNNER}/.ssh/known_hosts"
+chmod 644 "/home/${RUNNER}/.ssh/known_hosts"
+chown -R "${RUNNER}":"${RUNNER}" "/home/${RUNNER}"
+chown -R "${RUNNER}":"${RUNNERADMIN}" "${AGENT_TOOLSDIRECTORY}" "${ACT_TOOLSDIRECTORY}" /github
+
+apt-get clean
+rm -rf /var/cache/* /var/log/* /var/lib/apt/lists/* /tmp/* || true
+EOF
+
+LABEL org.opencontainers.image.created="${BUILD_DATE}"
+LABEL org.opencontainers.image.vendor="${BUILD_OWNER}"
+LABEL org.opencontainers.image.url="https://git.ipng.ch/${BUILD_OWNER}/${BUILD_REPO}"
+LABEL org.opencontainers.image.source="https://git.ipng.ch/${BUILD_OWNER}/${BUILD_REPO}"
+LABEL org.opencontainers.image.version="${BUILD_TAG_VERSION}"
+LABEL org.opencontainers.image.title="${BUILD_TAG}-${TARGETARCH}"
+LABEL org.opencontainers.image.description="IPng Debian Runner — Gitea Actions runner image based on debian:13-slim, with git-lfs, rsync and Go"
+LABEL org.opencontainers.image.revision="${BUILD_REF}"
+
+USER ${RUNNER}