Add TTL feature for cached files and folders

DOCS.md

@@ -6,6 +6,7 @@ The following parameters are used to configure the plugin:
 - **restore** - instruct plugin to restore cache, can be `true` or `false`
 - **rebuild** - instruct plugin to rebuild cache, can be `true` or `false`
 - **mount** - list of folders or files to cache
+- **ttl** - maximum cache lifetime in days
 
 ## Examples
 ```yaml
@@ -36,6 +37,24 @@ pipeline:
 
 The example above illustrates a typical Node.js project Drone configuration. It caches the `./node_modules` directory to a mounted volume on the host system: `/tmp/cache`. This prevents `npm` from downloading and installing the dependencies for every build.
 
+## Using cache lifetime
+It is possible to limit the lifetime of cached files and folders.
+
+```yaml
+pipeline:
+  restore-cache:
+    image: drillster/drone-volume-cache
+    restore: true
+    mount:
+      - ./node_modules
+    # Mount the cache volume, needs "Trusted"
+    volumes:
+      - /tmp/cache:/cache
+    ttl: 7
+```
+
+The example above shows a situation where cached items older than 7 days will not be restored (they will be removed instead). Only the restore step needs the `ttl` parameter.
+
 ## Clearing Cache
 Should you want to clear the cache for a project, you can do so by including `[CLEAR CACHE]` in the commit message. The entire cache folder for the project will be cleared before it is restored. The rebuilding of cache will proceed as normal.
 

Dockerfile

@@ -2,7 +2,7 @@ FROM alpine:3.4
 MAINTAINER Michael de Wit <michael@drillster.com>
 
 COPY cacher.sh /usr/local/
-RUN mkdir /cache && apk add --no-cache bash rsync && chmod 755 /usr/local/cacher.sh
+RUN mkdir /cache && apk add --no-cache bash rsync findutils && chmod 755 /usr/local/cacher.sh
 VOLUME /cache
 
 ENTRYPOINT ["/usr/local/cacher.sh"]

cacher.sh

@@ -36,6 +36,16 @@ if [[ -n "$PLUGIN_REBUILD" && "$PLUGIN_REBUILD" == "true" ]]; then
         fi
     done
 elif [[ -n "$PLUGIN_RESTORE" && "$PLUGIN_RESTORE" == "true" ]]; then
+    # Remove files older than TTL
+    if [[ -n "$PLUGIN_TTL" && "$PLUGIN_TTL" > "0" ]]; then
+        if [[ $PLUGIN_TTL =~ ^[0-9]+$ ]]; then
+            echo "Removing files and (empty) folders older than $PLUGIN_TTL days..."
+            find "/cache/$DRONE_REPO_OWNER/$DRONE_REPO_NAME/$DRONE_JOB_NUMBER" -type f -ctime +$PLUGIN_TTL -delete
+            find "/cache/$DRONE_REPO_OWNER/$DRONE_REPO_NAME/$DRONE_JOB_NUMBER" -type d -ctime +$PLUGIN_TTL -empty -delete
+        else
+            echo "Invalid value for ttl, please enter a positive integer. Plugin will ignore ttl."
+        fi
+    fi
     # Restore from cache
     for source in "${SOURCES[@]}"; do
         if [ -d "/cache/$DRONE_REPO_OWNER/$DRONE_REPO_NAME/$DRONE_JOB_NUMBER/$source" ]; then