Key the apt cache per PHP version and drop the instrumentation

Run 536 proved the cache works -- ACTIONS_CACHE_URL is now populated, no
GHES warning, "Cache saved with key: apt-php-builder-deps-ARM64-v1" -- and
in doing so showed the key was wrong. The jobs that saved it were 8.1 and
8.2.

They take the ondrej PPA path, a handful of runtime packages, while 8.3
takes php-builder and its ~70 -dev packages. One shared key therefore lets
whichever job finishes first decide what every other job restores, and 8.1
is always first, at ~30s against 8.3's several minutes. 8.3 would have
restored a few runtime .debs it has no use for and then downloaded all 70
anyway. My "the dep list is the same for every PHP version" comment was
true only among the builder versions.

Keyed per version now, so each path caches what it actually installs. That
also picks up a small win on 8.1 and 8.2 rather than only avoiding harm.

Both temporary steps are gone. Report restored .debs was there to show the
cache URL arriving and the restore landing; both are established, so it
goes. Keep downloaded .debs stays -- it is not instrumentation, it disables
Ubuntu's docker-clean, without which there are no .debs left to cache.

Refs #178.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Uw545F1vveNJKjzLxdi2ks

.gitea/workflows/ci.yml

@@ -20,14 +20,20 @@ jobs:
       - uses: actions/checkout@v4
 
       # setup-php installs PHP 8.3+ through php-builder, which apt-installs ~70
-      # -dev packages before unpacking the build (#178). Ubuntu's own image
+      # -dev packages before unpacking the build (#178). Ubuntu's image deletes
-      # deletes the .debs after install, so every job re-downloads them from
+      # the .debs after install, so every job re-downloads them. Keeping them
-      # the archive. Keep them and restore them from the cache server, which
+      # and restoring them from the cache server, which lives in the cluster,
-      # lives in the cluster, turning a WAN download into a local one.
+      # turns a WAN download into a local one.
       #
-      # The dep list is the same for every PHP version on the builder path, so
+      # Keyed per PHP version because the install path differs by version and
-      # one shared key serves them all. Only the .debs are cached, never
+      # the package sets are not interchangeable: 8.3+ pulls the ~70 -dev
-      # /var/lib/apt/lists — a stale index is how you get 404s on install.
+      # packages through php-builder, while 8.1 and 8.2 come from the ondrej
+      # PPA as a handful of runtime packages. Sharing one key across both lets
+      # whichever job finishes first decide what the others restore, and 8.1 is
+      # always first.
+      #
+      # Only the .debs are cached, never /var/lib/apt/lists — a stale index is
+      # how you get 404s mid-install.
       - name: Keep downloaded .debs
         run: |
           sudo rm -f /etc/apt/apt.conf.d/docker-clean
@@ -38,16 +44,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: /var/cache/apt/archives/*.deb
-          key: apt-php-builder-deps-${{ runner.arch }}-v1
+          key: apt-php8.3-${{ runner.arch }}-v1
-
-      # Temporary, for #178: shows whether the cache actually served the
-      # builder's dependencies, and times the step that consumes them.
-      - name: Report restored .debs
-        run: |
-          echo "ACTIONS_CACHE_URL: ${ACTIONS_CACHE_URL:-<unset>}"
-          echo "restored .debs: $(ls /var/cache/apt/archives/*.deb 2>/dev/null | wc -l)"
-          echo "restored size:  $(du -sh /var/cache/apt/archives 2>/dev/null | cut -f1)"
-          date -u +'setup-php start: %H:%M:%S'
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
@@ -84,14 +81,20 @@ jobs:
       - uses: actions/checkout@v4
 
       # setup-php installs PHP 8.3+ through php-builder, which apt-installs ~70
-      # -dev packages before unpacking the build (#178). Ubuntu's own image
+      # -dev packages before unpacking the build (#178). Ubuntu's image deletes
-      # deletes the .debs after install, so every job re-downloads them from
+      # the .debs after install, so every job re-downloads them. Keeping them
-      # the archive. Keep them and restore them from the cache server, which
+      # and restoring them from the cache server, which lives in the cluster,
-      # lives in the cluster, turning a WAN download into a local one.
+      # turns a WAN download into a local one.
       #
-      # The dep list is the same for every PHP version on the builder path, so
+      # Keyed per PHP version because the install path differs by version and
-      # one shared key serves them all. Only the .debs are cached, never
+      # the package sets are not interchangeable: 8.3+ pulls the ~70 -dev
-      # /var/lib/apt/lists — a stale index is how you get 404s on install.
+      # packages through php-builder, while 8.1 and 8.2 come from the ondrej
+      # PPA as a handful of runtime packages. Sharing one key across both lets
+      # whichever job finishes first decide what the others restore, and 8.1 is
+      # always first.
+      #
+      # Only the .debs are cached, never /var/lib/apt/lists — a stale index is
+      # how you get 404s mid-install.
       - name: Keep downloaded .debs
         run: |
           sudo rm -f /etc/apt/apt.conf.d/docker-clean
@@ -102,16 +105,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: /var/cache/apt/archives/*.deb
-          key: apt-php-builder-deps-${{ runner.arch }}-v1
+          key: apt-php${{ matrix.php }}-${{ runner.arch }}-v1
-
-      # Temporary, for #178: shows whether the cache actually served the
-      # builder's dependencies, and times the step that consumes them.
-      - name: Report restored .debs
-        run: |
-          echo "ACTIONS_CACHE_URL: ${ACTIONS_CACHE_URL:-<unset>}"
-          echo "restored .debs: $(ls /var/cache/apt/archives/*.deb 2>/dev/null | wc -l)"
-          echo "restored size:  $(du -sh /var/cache/apt/archives 2>/dev/null | cut -f1)"
-          date -u +'setup-php start: %H:%M:%S'
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
@@ -157,14 +151,20 @@ jobs:
       - uses: actions/checkout@v4
 
       # setup-php installs PHP 8.3+ through php-builder, which apt-installs ~70
-      # -dev packages before unpacking the build (#178). Ubuntu's own image
+      # -dev packages before unpacking the build (#178). Ubuntu's image deletes
-      # deletes the .debs after install, so every job re-downloads them from
+      # the .debs after install, so every job re-downloads them. Keeping them
-      # the archive. Keep them and restore them from the cache server, which
+      # and restoring them from the cache server, which lives in the cluster,
-      # lives in the cluster, turning a WAN download into a local one.
+      # turns a WAN download into a local one.
       #
-      # The dep list is the same for every PHP version on the builder path, so
+      # Keyed per PHP version because the install path differs by version and
-      # one shared key serves them all. Only the .debs are cached, never
+      # the package sets are not interchangeable: 8.3+ pulls the ~70 -dev
-      # /var/lib/apt/lists — a stale index is how you get 404s on install.
+      # packages through php-builder, while 8.1 and 8.2 come from the ondrej
+      # PPA as a handful of runtime packages. Sharing one key across both lets
+      # whichever job finishes first decide what the others restore, and 8.1 is
+      # always first.
+      #
+      # Only the .debs are cached, never /var/lib/apt/lists — a stale index is
+      # how you get 404s mid-install.
       - name: Keep downloaded .debs
         run: |
           sudo rm -f /etc/apt/apt.conf.d/docker-clean
@@ -175,16 +175,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: /var/cache/apt/archives/*.deb
-          key: apt-php-builder-deps-${{ runner.arch }}-v1
+          key: apt-php8.3-${{ runner.arch }}-v1
-
-      # Temporary, for #178: shows whether the cache actually served the
-      # builder's dependencies, and times the step that consumes them.
-      - name: Report restored .debs
-        run: |
-          echo "ACTIONS_CACHE_URL: ${ACTIONS_CACHE_URL:-<unset>}"
-          echo "restored .debs: $(ls /var/cache/apt/archives/*.deb 2>/dev/null | wc -l)"
-          echo "restored size:  $(du -sh /var/cache/apt/archives 2>/dev/null | cut -f1)"
-          date -u +'setup-php start: %H:%M:%S'
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2