feat(builder): Less verbose buildpack output

part 2 of teamhephy/workflow#109

This fixes the excessive verbouse output when cycling through
all buildpacks /bin/detect and the app doesn't match such buildpack

This PR forwards the variable DEIS_DEBUG_BUILDPACK to the slugbuilder

Author: n0n0x

pkg/gitreceive/build.go

@@ -110,6 +110,14 @@ func build(
 		}
 	}
 
+    var buildPackDebug string
+    if buildPackDebugInterface, ok := appConf.Values["DEIS_BUILDPACK_DEBUG"]; ok {
+        if bpDbgStr, ok := buildPackDebugInterface.(string); ok {
+            log.Debug("Buildpack Debug is on")
+            buildPackDebug = bpDbgStr
+        }
+    }
+
 	_, disableCaching := appConf.Values["DEIS_DISABLE_CACHE"]
 	slugBuilderInfo := NewSlugBuilderInfo(appName, gitSha.Short(), disableCaching)
 
@@ -227,6 +235,7 @@ func build(
 			cacheKey,
 			gitSha.Short(),
 			buildPackURL,
+			buildPackDebug,
 			conf.StorageType,
 			conf.SlugBuilderImage,
 			slugBuilderImagePullPolicy,

pkg/gitreceive/k8s_util.go

@@ -125,6 +125,7 @@ func slugbuilderPod(
 	cacheKey,
 	gitShortHash string,
 	buildpackURL,
+	buildpackDebug,
 	storageType,
 	image string,
 	pullPolicy api.PullPolicy,
@@ -165,6 +166,10 @@ func slugbuilderPod(
 		addEnvToPod(pod, "BUILDPACK_URL", buildpackURL)
 	}
 
+    if buildpackDebug != "" {
+        addEnvToPod(pod, "DEIS_BUILDPACK_DEBUG", buildpackDebug)
+    }
+
 	return &pod
 }