hugo: Add service for building Hugo-based sites

By default, a `hugo-build-local@.service` systemd service is included,
for building Hugo-based sites as stored in a local Git repository (as
served by the `git` service), and into a volume (which is intended to be
served by the `nginx-serve-volume` service).

host/lhr01nuc/spec.bu

@@ -18,6 +18,8 @@ ignition:
       - local: service/coturn/spec.ign
       - local: service/radicale/spec.ign
       - local: service/navidrome/spec.ign
+      - local: service/rclone/spec.ign
+      - local: service/hugo/spec.ign
       - local: private/spec.ign
 
 passwd:

host/lhr01srv/spec.bu

@@ -19,6 +19,8 @@ ignition:
       - local: service/spectrum/spec.ign
       - local: service/radicale/spec.ign
       - local: service/navidrome/spec.ign
+      - local: service/rclone/spec.ign
+      - local: service/hugo/spec.ign
       - local: private/spec.ign
 
 passwd:

host/virtual/spec.bu

@@ -22,6 +22,7 @@ ignition:
       - local: service/writefreely/spec.ign
       - local: service/coturn/spec.ign
       - local: service/rclone/spec.ign
+      - local: service/hugo/spec.ign
 
 passwd:
   users:

service/hugo/Containerfile

@@ -0,0 +1,15 @@
+FROM docker.io/debian:bullseye-slim
+ARG VERSION=0.97.2
+
+RUN apt-get update -y && apt-get install -y --no-install-recommends \
+    ca-certificates curl git inotify-tools gosu
+
+ENV PACKAGE_URL https://github.com/gohugoio/hugo/releases/download/v${VERSION}/hugo_${VERSION}_Linux-64bit.tar.gz
+RUN curl -L ${PACKAGE_URL} | tar -C /bin --no-same-owner -xvzf - hugo && chmod +x /bin/hugo
+RUN apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false curl
+
+RUN addgroup --system --gid 10000 hugo
+RUN adduser --system --uid 10000 --ingroup hugo --no-create-home hugo
+
+COPY container/run-hugo /run-hugo
+ENTRYPOINT ["/run-hugo"]

service/hugo/container/run-hugo

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+set -eu
+
+# Set up shared variables.
+GIT_REPO="$1"
+GIT_BRANCH="$2"
+
+# Ensure correct usage and state.
+if test -z "$GIT_REPO"; then
+    echo "Git repository path is empty, please provide a valid path as the first argument."
+    exit 1
+elif test -z "$GIT_BRANCH"; then
+    echo "Git branch name is empty, please provide a valid branch name as the second argument."
+    exit 1
+elif test ! -e "/src/${GIT_REPO}/refs/heads/${GIT_BRANCH}"; then
+    echo "Unable to find HEAD reference for '${GIT_REPO}', branch '${GIT_BRANCH}', is this a valid Git repository?"
+    exit 2
+fi
+
+chown -R hugo:hugo /dest
+
+# Wait for updates to watched branch for the given site, and build static content anew.
+while true; do
+    gosu hugo /usr/bin/git clone --quiet --shared "/src/${GIT_REPO}" /tmp/src
+    gosu hugo /bin/hugo --verbose --source /tmp/src --destination /dest && rm -Rf /tmp/src
+    inotifywait -qq --event modify "/src/${GIT_REPO}/refs/heads/${GIT_BRANCH}" && break
+done

service/hugo/spec.bu

@@ -0,0 +1,8 @@
+variant: fcos
+version: 1.3.0
+storage:
+  trees:
+    - path: /etc/coreos-home-server/hugo
+      local: service/hugo/
+    - path: /etc/systemd/system
+      local: service/hugo/systemd/

service/hugo/systemd/hugo-build-local@.service

@@ -0,0 +1,21 @@
+[Unit]
+Description=Hugo Build for Local %I Repository
+Wants=container-build@hugo.service container-volume@hugo-build-%i.service git.service
+After=container-build@hugo.service container-volume@hugo-build-%i.service git.service
+
+[Service]
+Type=notify
+NotifyAccess=all
+SyslogIdentifier=%N
+Restart=on-failure
+Environment=PODMAN_SYSTEMD_UNIT=%n
+Environment=GIT_REPO=%i.git GIT_BRANCH=master
+ExecStart=/bin/podman run --replace --name %p-%i --net internal --sdnotify=conmon \
+                          --volume git:/src:z,ro \
+                          --volume hugo-build-%i:/dest:z \
+                          localhost/hugo:latest $GIT_REPO $GIT_BRANCH
+ExecStop=/bin/podman stop --ignore --time 10 %p-%i
+ExecStopPost=/bin/podman rm --ignore --force %p-%i
+
+[Install]
+WantedBy=multi-user.target