Replace bind-mount with volume as Bazel Cache

.devcontainer/devcontainer.json

@@ -2,7 +2,9 @@
     "image": "mcr.microsoft.com/devcontainers/javascript-node:0-18",
     "features": {
         "ghcr.io/devcontainers/features/git:1": {},
-        "ghcr.io/devcontainers/features/git-lfs:1": {},
+        "ghcr.io/devcontainers/features/git-lfs:1": {
+            "autoPull": "false" // do not automatically pull LFS files when creating the container
+        },
         "ghcr.io/devcontainers/features/docker-in-docker:2": {},
         "ghcr.io/devcontainers-extra/features/pre-commit:2": {
             "version": "4.2.0"

README.md

@@ -24,14 +24,12 @@ It should contain the following:
 ````json
 {
     "name": "eclipse-s-core",
-    "image": "ghcr.io/eclipse-score/devcontainer:<version>",
-    "initializeCommand": "mkdir -p ${localEnv:HOME}/.cache/bazel"
+    "image": "ghcr.io/eclipse-score/devcontainer:<version>"
 }
 ````
 
 The `<version>` must be a [valid, published release](https://github.com/eclipse-score/devcontainer/tags).
 You can also use `latest` as `<version>` to automatically follow the `main` branch - but be aware that this can result in undesired updates.
-The `initializeCommand` is required to ensure the default Bazel cache directory exists on your host system.
 
 To start using the container, click the **Reopen in Container** button when prompted by Visual Studio Code:
 

src/s-core-devcontainer/.devcontainer/s-core-local/devcontainer-feature.json

@@ -36,9 +36,9 @@
     "postCreateCommand": "if [ -f .bazelversion ] && [ \"$(cat .bazelversion)\" != \"$(dpkg --list | grep 'ii  bazel   ' | awk '{print $3}')\" ]; then sudo apt-get update && sudo apt-get install -y --allow-downgrades bazel=$(cat .bazelversion); fi",
     "mounts": [
         {
-            "source": "${localEnv:HOME}/.cache/bazel", // default Bazel cache directory
+            "source": "eclipse-s-core-bazel-cache",
             "target": "/var/cache/bazel",
-            "type": "bind"
+            "type": "volume"
         }
     ]
 }

src/s-core-devcontainer/.devcontainer/s-core-local/on_create_command.sh

@@ -1,15 +1,24 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-# In some scenarios (like CodeSpaces), apparently not all (or even any?)
-# bind mounts to the host are done and /var/cache/bazel does not exist.
-# See devcontainer-feature.json, where this mount is defined.
-# Hence, if /var/cache/bazel exists, it was mounted from the host,
-# and we configure Bazel to use /var/cache/bazel as cache.
-# This way, Bazel re-uses a bind-mounted cache from the host machine, while
-# still using the default cache (${HOME}/.cache/bazel) if no such cache exists.
+# Enable persistent Bazel cache
+#
+# Usually, a volume is mounted to /var/cache/bazel (see
+# devcontainer-feature.json). This shall be used as Bazel cache, which is then
+# preserved across container re-starts. Since the volume has a fixed
+# name ("eclipse-s-core-bazel-cache"), it is even used across all Eclipse
+# S-CORE DevContainer instances.
 if [ -d /var/cache/bazel ]; then
-  echo "Configuring Bazel to use /var/cache/bazel as cache..."
+  echo "Bazel Cache: /var/cache/bazel exists. Checking ownership and configuring Bazel to use it as cache..."
+  current_owner_group=$(stat -c "%U:%G" /var/cache/bazel)
+  current_user_group="$(id -un):$(id -gn)"
+  if [ "${current_owner_group}" = "${current_user_group}" ]; then
+    echo "Bazel Cache: /var/cache/bazel is already owned by ${current_user_group}. "
+  else
+    echo "Bazel Cache: /var/cache/bazel is not owned by ${current_owner_group}. Setting ownership (this may take a few seconds) ..."
+    sudo chown -R "${current_user_group}" /var/cache/bazel
+  fi
+  echo "Bazel Cache: Configuring Bazel to use /var/cache/bazel as cache..."
   echo "startup --output_user_root=/var/cache/bazel" >> ~/.bazelrc
 fi