Refactor CI into composite actions + repo variables

The workflow was mostly inline bash. Moves the logic into reusable
composite actions under .gitea/actions/, keeps host paths in the
YOCTO_HOME repo variable, adds a workflow_dispatch skip-build option
and publishes step outputs (build dir, image list, kas path).

.gitea/actions/build-image/action.yml

@@ -0,0 +1,117 @@
+name: build-image
+description: >-
+  Build a kas project in a persistent directory and expose the flashable
+  images. The workspace is synced into the build dir instead of built in
+  place, because checkout cleans ignored files (build/, extern/) and bitbake
+  reuse depends on sstate-cache surviving between runs.
+inputs:
+  project:
+    description: kas configuration file, relative to the repository
+    required: false
+    default: .config.yaml
+  machine:
+    description: Machine the images are deployed for
+    required: false
+    default: raspberrypi4-64
+  image-prefix:
+    description: Artifact filename prefix in the deploy dir
+    required: false
+    default: rpilinux-image
+  skip-build:
+    description: Set to true to only collect images from an existing build dir
+    required: false
+    default: "false"
+outputs:
+  build-dir:
+    description: Persistent project directory on the runner
+    value: ${{ steps.locate.outputs.build-dir }}
+  image-dir:
+    description: Deploy dir bitbake wrote to
+    value: ${{ steps.locate.outputs.image-dir }}
+  images:
+    description: Newline separated artifact filenames
+    value: ${{ steps.collect.outputs.images }}
+runs:
+  using: composite
+  steps:
+    - name: Sync workspace into persistent build dir
+      if: ${{ inputs.skip-build != 'true' }}
+      shell: bash
+      run: |
+        set -euo pipefail
+        SRC="$(pwd)"
+        DST="${YOCTO_HOME:-$HOME/yocto-build}/$(basename "$GITHUB_REPOSITORY")"
+        # checkout deletes ignored files, so the build tree must live elsewhere
+        if [ "$SRC" = "$DST" ]; then
+          echo "::error::workspace == build dir ($SRC); point YOCTO_HOME somewhere else"
+          exit 1
+        fi
+        echo "syncing $SRC -> $DST"
+        mkdir -p "$DST"
+        # .git stays (kas requires a repo); extern/ + build/ only exist in DST,
+        # so --delete cannot reach them
+        rsync -a --delete --exclude /build/ --exclude /extern/ ./ "$DST/"
+
+    - name: kas build
+      if: ${{ inputs.skip-build != 'true' }}
+      shell: bash
+      run: |
+        set -euo pipefail
+        cd "${YOCTO_HOME:-$HOME/yocto-build}/$(basename "$GITHUB_REPOSITORY")"
+        git config --global --add safe.directory "$PWD" || true
+        "${YOCTO_HOME:-$HOME/yocto-build}/venv/bin/kas" build
+
+    - name: Locate deploy dir
+      id: locate
+      shell: bash
+      run: |
+        set -euo pipefail
+        BUILD_DIR="${YOCTO_HOME:-$HOME/yocto-build}/$(basename "$GITHUB_REPOSITORY")"
+        IMAGE_DIR="$(find "$BUILD_DIR/build" -type d -path "*/tmp/deploy/images/${{ inputs.machine }}" | head -1)"
+        if [ -z "$IMAGE_DIR" ]; then
+          echo "::error::no deploy dir for ${{ inputs.machine }} under $BUILD_DIR/build"
+          exit 1
+        fi
+        echo "build-dir=$BUILD_DIR" >> "$GITHUB_OUTPUT"
+        echo "image-dir=$IMAGE_DIR" >> "$GITHUB_OUTPUT"
+
+    - name: Collect artifacts
+      id: collect
+      shell: bash
+      run: |
+        set -euo pipefail
+        IMAGE_DIR="${{ steps.locate.outputs.image-dir }}"
+        shopt -s nullglob
+        # only the timestamped names: the short ones are hardlinks to the same
+        # inode and would upload every image twice
+        FILES=("${IMAGE_DIR}/${{ inputs.image-prefix }}."*.rootfs-[0-9]*.wic.* \
+               "${IMAGE_DIR}/${{ inputs.image-prefix }}-*.rootfs-[0-9]*.wic.*")
+        if [ "${#FILES[@]}" -eq 0 ]; then
+          echo "::error::no flashable .wic image for ${{ inputs.machine }} in $IMAGE_DIR"
+          exit 1
+        fi
+        mkdir -p dist
+        cp -v "${FILES[@]}" dist/
+        ( cd dist && sha256sum * > SHA256SUMS )
+        ls -lh dist
+        printf 'images=%s\n' "$(ls dist | tr '\n' ' ')" >> "$GITHUB_OUTPUT"
+
+    - name: Summarise
+      shell: bash
+      run: |
+        set -euo pipefail
+        SUMMARY="${GITHUB_STEP_SUMMARY:-}"
+        [ -n "$SUMMARY" ] || exit 0
+        {
+          echo "## ${{ inputs.image-prefix }} for ${{ inputs.machine }}"
+          echo
+          echo "| artifact | sha256 |"
+          echo "| --- | --- |"
+          ( cd dist && while read -r sum file; do
+              [ "$file" = SHA256SUMS ] || echo "| \`$file\` | \`${sum:0:16}\` |"
+            done < SHA256SUMS )
+          echo
+          echo "Flash with \`bzcat <image> | sudo dd of=/dev/sdX bs=4M status=progress\`."
+          echo
+          echo "Incremental build tree: \`${{ steps.locate.outputs.build-dir }}\`"
+        } >> "$SUMMARY"

.gitea/actions/check-build-host/action.yml

@@ -0,0 +1,37 @@
+name: check-build-host
+description: >-
+  Report the build host and fail fast when executables, CPU or disk that the
+  build needs are missing - a mistake should cost seconds, not hours.
+inputs:
+  tools:
+    description: Space separated executables that must be on PATH
+    required: false
+    default: git python3
+  min-disk-gb:
+    description: Warn when the build filesystem has less than this much free
+    required: false
+    default: "100"
+runs:
+  using: composite
+  steps:
+    - name: Host report
+      shell: bash
+      run: |
+        set -euo pipefail
+        echo "os     : $(. /etc/os-release && echo "$PRETTY_NAME") ($(uname -m), $(uname -r))"
+        echo "user   : $(id -un)  home=$HOME"
+        echo "cpu    : $(nproc) cores / $(awk '/MemTotal/{printf "%.0fG", $2/1048576}' /proc/meminfo) ram"
+        df -h . | tail -1 | sed 's/^/disk   : /'
+        missing=""
+        for tool in ${{ inputs.tools }}; do
+          command -v "$tool" >/dev/null 2>&1 || missing="$missing $tool"
+        done
+        if [ -n "$missing" ]; then
+          echo "::error::Host is missing:$missing"
+          echo "Install them on the runner host, e.g. sudo apt-get install -y $missing"
+          exit 1
+        fi
+        free_gb="$(df --output=avail -BG . | tail -1 | tr -d ' ')"
+        if [ "$free_gb" -lt "${{ inputs.min-disk-gb }}" ]; then
+          echo "::warning::only ${free_gb}G free on $(df --output=target . | tail -1); expected >= ${{ inputs.min-disk-gb }}G"
+        fi

.gitea/actions/setup-kas/action.yml

@@ -0,0 +1,34 @@
+name: setup-kas
+description: Create or reuse the persistent python venv that holds kas.
+inputs:
+  requirement:
+    description: pip requirement for kas (pinned, e.g. kas==5.5)
+    required: false
+    default: kas
+outputs:
+  kas:
+    description: Absolute path of the kas executable
+    value: ${{ steps.venv.outputs.kas }}
+  reused:
+    description: "true when the venv already existed (warm run)"
+    value: ${{ steps.venv.outputs.reused }}
+runs:
+  using: composite
+  steps:
+    - name: Prepare venv
+      id: venv
+      shell: bash
+      run: |
+        set -euo pipefail
+        BUILD_ROOT="${YOCTO_HOME:-$HOME/yocto-build}"
+        VENV="$BUILD_ROOT/venv"
+        mkdir -p "$BUILD_ROOT"
+        if [ -d "$VENV" ]; then
+          echo "reused=true" >> "$GITHUB_OUTPUT"
+        else
+          echo "reused=false" >> "$GITHUB_OUTPUT"
+          python3 -m venv "$VENV"
+        fi
+        "$VENV/bin/pip" install --quiet --upgrade "${{ inputs.requirement }}"
+        echo "kas=$VENV/bin/kas" >> "$GITHUB_OUTPUT"
+        echo "kas $($VENV/bin/kas --version) in $VENV"

.gitea/workflows/build.yaml

@@ -1,28 +1,29 @@
 name: Build RPi image
 
-# Yocto (kas) build of rpilinux-image for raspberrypi4-64.
+# Yocto (kas) build of rpilinux-image. Steps live in .gitea/actions/* so this
+# file stays a description of the pipeline, not a shell script.
 #
-# Runs on the dedicated host runner (label "yocto:host", Ryzen 9 box "ada").
+# Host-specific paths come from repo settings (Settings -> Actions ->
-# Everything persists in $YOCTO_HOME: extern/ (layer clones) + build/ (sstate)
+# Variables), so the workflow is not tied to one machine:
-# survive between runs -> incremental builds after the first.
+#   YOCTO_HOME   persistent build dir on the runner
-# $YOCTO_HOME comes from the runner config (runner.envs.YOCTO_HOME =
+# Order of precedence for the build dir: this variable, then the runner's
-# /home/bl/yocto-build, on the 1.8T disk); falls back to $HOME/yocto-build.
+# own YOCTO_HOME (runner.envs), then $HOME/yocto-build.
-#
-# First build takes hours (poky fetch + full image) -> runner.timeout >= 8h.
-#
-# First build takes hours (poky fetch + full image) -> runner.timeout >= 8h.
 
 on:
   push:
-    # main is release-protected; ci/* branches are free scratch space
+    # main is release protected, ci/* branches are free scratch space
     branches: [main, 'ci/*']
   pull_request:
-    # gates merges into main, and provides the commit status that a
+    # gates merges into main and posts the commit status that branch
-    # "require status checks" branch-protection rule waits for
+    # protection waits for
     branches: [main]
   workflow_dispatch:
+    inputs:
+      skip-build:
+        description: Collect images from the existing build dir instead of rebuilding
+        type: boolean
+        default: false
 
-# Never run two builds at once on the same (single) runner.
 concurrency:
   group: yocto-rpi-build
   cancel-in-progress: false
@@ -30,110 +31,46 @@ concurrency:
 permissions:
   contents: read
 
+env:
+  YOCTO_HOME: ${{ vars.YOCTO_HOME }}
+  MACHINE: raspberrypi4-64
+  IMAGE_PREFIX: rpilinux-image
+
+defaults:
+  run:
+    shell: bash
+
 jobs:
   build:
     runs-on: yocto
     timeout-minutes: 600
     steps:
-      - uses: builtin:checkout
+      - name: Check out sources
+        uses: builtin:checkout
 
-      - name: Probe environment and host dependencies
+      - name: Verify build host
-        run: |
+        uses: $/.gitea/actions/check-build-host
-          echo "=== runner environment ==="
+        with:
-          uname -a
+          tools: git python3 curl wget rsync gawk xz diffstat chrpath bison flex node
-          [ -r /etc/os-release ] && . /etc/os-release && echo "$PRETTY_NAME"
+          min-disk-gb: "200"
-          echo "HOME=$HOME  workspace=$(pwd)  nproc=$(nproc)"
-          df -h "$HOME" | tail -1
-          free -h 2>/dev/null | sed -n 2p || true
-          command -v docker >/dev/null && docker info --format 'docker: {{.ServerVersion}}' 2>/dev/null || echo "no docker daemon"
-          echo "=== dependency check ==="
-          set -e
-          missing=""
-          for t in git python3 curl wget rsync gawk xz diffstat chrpath node npm; do
-            command -v "$t" >/dev/null 2>&1 || missing="$missing $t"
-          done
-          if [ -n "$missing" ]; then
-            echo "::error::Missing host tools:$missing"
-            echo "Install on the runner host, e.g.:"
-            echo '  sudo apt-get install -y --no-install-recommends build-essential \
-                  bison flex chrpath curl diffstat file gawk git libpython3-dev libssl-dev \
-                  make python3 python3-venv python3-pip python3-dev rsync swig unzip \
-                  wget xz-utils zstd bzip2 nodejs npm'
-            exit 1
-          fi
 
-      - name: Set up kas (persistent venv)
+      - name: Set up kas
-        run: |
+        id: kas
-          set -e
+        uses: $/.gitea/actions/setup-kas
-          export YOCTO_HOME="${YOCTO_HOME:-$HOME/yocto-build}"
+        with:
-          mkdir -p "$YOCTO_HOME"
+          requirement: kas==5.5
-          [ -d "$YOCTO_HOME/venv" ] || python3 -m venv "$YOCTO_HOME/venv"
-          "$YOCTO_HOME/venv/bin/pip" -q install -U kas
-          "$YOCTO_HOME/venv/bin/kas" --version
 
-      - name: Sync to persistent build dir and build
+      - name: Build image
-        run: |
+        id: image
-          set -euo pipefail
+        uses: $/.gitea/actions/build-image
-          export YOCTO_HOME="${YOCTO_HOME:-$HOME/yocto-build}"
+        with:
-          SRC="$(pwd)"
+          machine: ${{ env.MACHINE }}
-          DST="$YOCTO_HOME/yocto_rpi"
+          image-prefix: ${{ env.IMAGE_PREFIX }}
-          # Safety: builtin:checkout cleans ignored files (build/, extern/),
+          skip-build: ${{ github.event.inputs.skip-build }}
-          # so the build tree must NOT be the ephemeral workspace.
-          if [ "$SRC" = "$DST" ]; then
-            echo "::error::workspace == persistent dir ($SRC); keep the runner WorkingDirectory outside YOCTO_HOME"
-            exit 1
-          fi
-          echo "syncing $SRC -> $DST"
-          mkdir -p "$DST"
-          # .git is copied (kas expects a git repo); extern/ and build/ exist
-          # only in DST and are excluded, so --delete cannot touch them.
-          rsync -a --delete --exclude /build/ --exclude /extern/ ./ "$DST/"
-          cd "$DST"
-          git config --global --add safe.directory "$DST" || true
-          "$YOCTO_HOME/venv/bin/kas" build
 
-      - name: Collect images
+      - name: Upload image
-        run: |
-          set -euo pipefail
-          export YOCTO_HOME="${YOCTO_HOME:-$HOME/yocto-build}"
-          WS="$(pwd)"   # workspace; upload-artifact's path is relative to it
-          cd "$YOCTO_HOME/yocto_rpi"
-          IMG_DIR="$(find build -type d -path '*/tmp/deploy/images/raspberrypi4-64' | head -1)"
-          if [ -z "$IMG_DIR" ]; then
-            echo "::error::no deploy dir found under build/"
-            exit 1
-          fi
-          echo "images in: $IMG_DIR"
-          mkdir -p "$WS/dist"
-          shopt -s nullglob
-          # only the timestamped canonical names - the short "...rootfs.wic.bz2"
-          # entries are hardlinks to the same inode (would double the upload)
-          FILES=("$IMG_DIR"/rpilinux-image-*.rootfs-[0-9]*.wic.bz2 "$IMG_DIR"/rpilinux-image-*.rootfs-[0-9]*.wic.bmap)
-          if [ ${#FILES[@]} -eq 0 ]; then
-            echo "::error::no flashable .wic image found in $IMG_DIR"
-            exit 1
-          fi
-          cp -v "${FILES[@]}" "$WS/dist/"
-          ( cd "$WS/dist" && sha256sum * > SHA256SUMS )
-          ls -lh "$WS/dist"
-          SUMMARY="${GITEA_STEP_SUMMARY:-${GITHUB_STEP_SUMMARY:-}}"
-          if [ -n "$SUMMARY" ]; then
-            {
-              echo "## RPi4 image built"
-              echo
-              echo "| file | sha256 |"
-              echo "|---|---|"
-              ( cd "$WS/dist" && while read -r sum f; do echo "| \`$f\` | \`${sum:0:16}\` |"; done < SHA256SUMS )
-              echo
-              echo "Flash: \`bzcat <file> | sudo dd of=/dev/sdX bs=4M status=progress\`"
-              echo
-              echo "Build tree (incremental) on runner host: \`$YOCTO_HOME/yocto_rpi\`"
-            } >> "$SUMMARY"
-          fi
-
-      - name: Upload images
         uses: actions/upload-artifact@v4
         with:
-          name: rpilinux-image-rpi4
+          name: ${{ env.IMAGE_PREFIX }}-${{ env.MACHINE }}
           path: dist/
           retention-days: 14