fix(outprint): run only one package sync at a time

charts/outprint/Chart.yaml

@@ -15,7 +15,7 @@ sources:
   - https://github.com/taskmedia/helm
 icon: https://media.task.media/images/logo.png
 type: application
-version: 1.3.1
+version: 1.3.2
 # outprint release tag without the leading v
 appVersion: "1.1.0"
 
@@ -32,5 +32,5 @@ annotations:
     - name: outprint-injector
       image: ghcr.io/taskmedia/outprint-injector:1.1.0
   artifacthub.io/changes: |
-    - kind: changed
-      description: Bump Outprint to 1.1.0
+    - kind: fixed
+      description: Only one package sync works on the volume at a time; the first Job and the CronJob could overlap

charts/outprint/files/packages-activate.sh

@@ -3,15 +3,15 @@
 set -eu
 
 PK=/packages
-[ -f "$PK/.pending" ] || { echo "no change"; exit 0; }
-sha="$(cat "$PK/.pending")"
+[ -f /state/pending ] || { echo "no change"; exit 0; }
+sha="$(cat /state/pending)"
 had_revision=false
 [ -f "$PK/.revision" ] && had_revision=true
 
 ln -sfn "rev-$sha" "$PK/.current.tmp"
 mv -T "$PK/.current.tmp" "$PK/current"
 printf '%s\n' "$sha" >"$PK/.revision"
-rm -f "$PK/.pending"
+rm -rf "$PK/.lock"
 echo "activated $sha"
 
 # newest first; the active revision is the newest

charts/outprint/files/packages-sync.sh

@@ -1,14 +1,34 @@
 # Resolve the ref of every source in /scripts/sources.json to a commit. If the
 # set of commits differs from the active revision, check every source out (Git
 # LFS included), merge the packages into /packages/rev-<id> and leave the id in
-# /packages/.pending for the validate and activate steps. Never touches the
-# active revision. Any failure (a ref that does not resolve, a pinned commit
+# /state/pending (private to this pod) for the validate and activate steps.
+# Never touches the active revision. Only one sync works on the volume at a
+# time: /packages/.lock is taken here and released by the activate step. Any failure (a ref that does not resolve, a pinned commit
 # that differs, a package name that two sources provide) stops here.
 set -eu
 
 PK=/packages
+STATE=/state
 SOURCES=/scripts/sources.json
-rm -f "$PK/.pending"
+LOCK="$PK/.lock"
+LOCK_MAX_AGE=180
+rm -f "$STATE/pending"
+
+# mkdir is atomic. A lock older than LOCK_MAX_AGE seconds is left over from a
+# sync that died or failed validation, and is taken over.
+if ! mkdir "$LOCK" 2>/dev/null; then
+  age=$(( $(date +%s) - $(cat "$LOCK/since" 2>/dev/null || echo 0) ))
+  if [ "$age" -lt "$LOCK_MAX_AGE" ]; then
+    echo "another sync holds the lock (started ${age}s ago): skipping"
+    exit 0
+  fi
+  echo "taking over a stale lock (${age}s old)"
+  rm -rf "$LOCK"
+  mkdir "$LOCK"
+fi
+date +%s >"$LOCK/since"
+# Without a pending revision nothing follows this step, so give the lock back.
+trap '[ -f "$STATE/pending" ] || rm -rf "$LOCK"' EXIT
 
 apk add --no-cache git-lfs openssh-client >/dev/null
 
@@ -130,5 +150,5 @@ done
 printf '%s' "$resolved" >"$rev/.sources"
 rm -rf "$PK/.work"
 chmod -R a+rX "$rev"
-printf '%s\n' "$id" >"$PK/.pending"
-chmod a+r "$PK/.pending"
+printf '%s\n' "$id" >"$STATE/pending"
+chmod a+r "$STATE/pending"

charts/outprint/files/packages-validate.sh

@@ -2,8 +2,8 @@
 # With a service configuration the roots come from the environment.
 set -eu
 
-[ -f /packages/.pending ] || { echo "nothing to validate"; exit 0; }
-sha="$(cat /packages/.pending)"
+[ -f /state/pending ] || { echo "nothing to validate"; exit 0; }
+sha="$(cat /state/pending)"
 export OUTPRINT_TEMPLATES_ROOT="/packages/rev-$sha/templates"
 export OUTPRINT_CONFIGURATIONS_ROOT="/packages/rev-$sha/configurations"
 exec outprint validate --service-config /etc/outprint/service.yaml

charts/outprint/templates/_packages-sync.tpl

@@ -27,6 +27,7 @@ initContainers:
     volumeMounts:
       - { name: packages, mountPath: /packages }
       - { name: scripts, mountPath: /scripts, readOnly: true }
+      - { name: state, mountPath: /state }
       {{- range $sources }}
       {{- if .sshKeySecret }}
       - { name: {{ printf "ssh-%s" .name }}, mountPath: {{ printf "/ssh/%s" .name | quote }}, readOnly: true }
@@ -47,6 +48,7 @@ initContainers:
     volumeMounts:
       - { name: packages, mountPath: /packages, readOnly: true }
       - { name: scripts, mountPath: /scripts, readOnly: true }
+      - { name: state, mountPath: /state, readOnly: true }
       - { name: service-config, mountPath: /etc/outprint, readOnly: true }
       - { name: tmp, mountPath: /tmp }
 containers:
@@ -72,6 +74,7 @@ containers:
     volumeMounts:
       - { name: packages, mountPath: /packages }
       - { name: scripts, mountPath: /scripts, readOnly: true }
+      - { name: state, mountPath: /state, readOnly: true }
       - { name: tmp, mountPath: /tmp }
 volumes:
   - name: packages
@@ -85,6 +88,9 @@ volumes:
       name: {{ include "outprint.fullname" . }}-service
   - name: tmp
     emptyDir: { sizeLimit: 64Mi }
+  # What this pod has prepared: the id of the revision for validate and activate.
+  - name: state
+    emptyDir: { sizeLimit: 1Mi }
   {{- range $sources }}
   {{- if .sshKeySecret }}
   - name: {{ printf "ssh-%s" .name }}