feat(slugbuilder-cache): allow turning caching off completely

When the slugbuilder doesn't receive a CACHE_PATH, it'll skip caching.
Adding DEIS_DISABLE_CACHE config variable will disable the cache and
will not define CACHE_PATH on the slugbuilder pod, preventing it from
reading/writing cache.

Author: jeroenvisser101

pkg/gitreceive/k8s_util.go

@@ -108,9 +108,12 @@ func slugbuilderPod(
 	pod.Spec.Containers[0].Name = slugBuilderName
 	pod.Spec.Containers[0].Image = image
 
+	if _, ok := env["DEIS_DISABLE_CACHE"]; !ok {
+		addEnvToPod(pod, cachePath, cacheKey)
+	}
+
 	addEnvToPod(pod, tarPath, tarKey)
 	addEnvToPod(pod, putPath, putKey)
-	addEnvToPod(pod, cachePath, cacheKey)
 	addEnvToPod(pod, sourceVersion, gitShortHash)
 	addEnvToPod(pod, builderStorage, storageType)
 

pkg/gitreceive/k8s_util_test.go

@@ -56,11 +56,15 @@ func TestBuildPod(t *testing.T) {
 	env := make(map[string]interface{})
 	env["KEY"] = "VALUE"
 
+	cacheDisabledEnv := make(map[string]interface{})
+	cacheDisabledEnv["DEIS_DISABLE_CACHE"] = "1"
+
 	var pod *api.Pod
 
 	slugBuilds := []slugBuildCase{
 		{true, "test", "default", emptyEnv, "tar", "put-url", "cache-url", "deadbeef", "", "", api.PullAlways, ""},
 		{true, "test", "default", env, "tar", "put-url", "cache-url", "deadbeef", "", "", api.PullAlways, ""},
+		{true, "test", "default", cacheDisabledEnv, "tar", "put-url", "cache-url", "deadbeef", "", "", api.PullAlways, ""},
 		{true, "test", "default", emptyEnv, "tar", "put-url", "cache-url", "deadbeef", "buildpack", "", api.PullAlways, ""},
 		{true, "test", "default", env, "tar", "put-url", "cache-url", "deadbeef", "buildpack", "", api.PullAlways, ""},
 		{true, "test", "default", env, "tar", "put-url", "cache-url", "deadbeef", "buildpack", "customimage", api.PullAlways, ""},
@@ -95,7 +99,14 @@ func TestBuildPod(t *testing.T) {
 		checkForEnv(t, pod, "SOURCE_VERSION", build.gitShortHash)
 		checkForEnv(t, pod, "TAR_PATH", build.tarKey)
 		checkForEnv(t, pod, "PUT_PATH", build.putKey)
-		checkForEnv(t, pod, "CACHE_PATH", build.cacheKey)
+
+		if _, ok := build.env["DEIS_DISABLE_CACHE"]; !ok {
+			checkForEnv(t, pod, "CACHE_PATH", build.cacheKey)
+		} else {
+			if cachePath, err := envValueFromKey(pod, "CACHE_PATH"); err == nil {
+				t.Errorf("expected CACHE_PATH not to be defined but it was defined with %v", cachePath)
+			}
+		}
 
 		if build.buildPack != "" {
 			checkForEnv(t, pod, "BUILDPACK_URL", build.buildPack)