refactor: use only a single implementation for cache purging

This change moves cache clearing into the repo plugin, and standardizes on a single way of clearing the cache.

plugins/repo/src/subcommands/purge-cache/purge-cache.go

@@ -2,11 +2,9 @@ package main
 
 import (
 	"flag"
-	"os"
-	"strings"
 
 	"github.com/dokku/dokku/plugins/common"
-	"github.com/dokku/dokku/plugins/config"
+	"github.com/dokku/dokku/plugins/repo"
 )
 
 // deletes the contents of the build cache stored in the repository
@@ -16,25 +14,9 @@ func main() {
 	if appName == "" {
 		common.LogFail("Please specify an app to run the command on")
 	}
-	err := common.VerifyAppName(appName)
-	if err != nil {
-		common.LogFail(err.Error())
-	}
 
-	cacheDir := strings.Join([]string{common.MustGetEnv("DOKKU_ROOT"), appName, "cache"}, "/")
-	cacheHostDir := strings.Join([]string{common.MustGetEnv("DOKKU_HOST_ROOT"), appName, "cache"}, "/")
-	dokkuGlobalRunArgs := common.MustGetEnv("DOKKU_GLOBAL_RUN_ARGS")
-	image := config.GetWithDefault(appName, "DOKKU_IMAGE", os.Getenv("DOKKU_IMAGE"))
-	if info, _ := os.Stat(cacheDir); info != nil && info.IsDir() {
-		purgeCacheCmd := common.NewShellCmd(strings.Join([]string{
-			common.DockerBin(),
-			"run --rm", dokkuGlobalRunArgs,
-			"-v", strings.Join([]string{cacheHostDir, ":/cache"}, ""), image,
-			`find /cache -depth -mindepth 1 -maxdepth 1 -exec rm -Rf {} ;`}, " "))
-		purgeCacheCmd.Execute()
-		err := os.MkdirAll(cacheDir, 0644)
-		if err != nil {
-			common.LogFail(err.Error())
-		}
+	err := repo.PurgeCache(appName)
+	if err != nil {
+		common.LogWarn(err.Error())
 	}
 }

plugins/repo/src/triggers/pre-delete/pre-delete.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"flag"
+
+	"github.com/dokku/dokku/plugins/common"
+	"github.com/dokku/dokku/plugins/repo"
+)
+
+// destroys the buildpacks property for a given app container
+func main() {
+	flag.Parse()
+	appName := flag.Arg(0)
+
+	err := repo.PurgeCache(appName)
+	if err != nil {
+		common.LogFail(err.Error())
+	}
+}