fix(pkg/gitreceive/config.go): require dependent image names (#377)

so that the builder doesn’t start with stale slug builder or docker builder images

Closes #376
Closes #357

Author: arschles

pkg/gitreceive/config.go

@@ -33,8 +33,8 @@ type Config struct {
 	ObjectStorageTickDurationMSec int    `envconfing:"OBJECT_STORAGE_TICK_DURATION" default:"500"`
 	ObjectStorageWaitDurationMSec int    `envconfig:"OBJECT_STORAGE_WAIT_DURATION" default:"300000"` // 5 minutes
 	SessionIdleIntervalMsec       int    `envconfig:"SESSION_IDLE_INTERVAL" default:"10000"`         // 10 seconds
-	SlugBuilderImage              string `envconfig:"SLUGBUILDER_IMAGE_NAME" default:"quay.io/deisci/slugbuilder:v2-beta"`
-	DockerBuilderImage            string `envconfig:"DOCKERBUILDER_IMAGE_NAME" default:"quay.io/deisci/dockerbuilder:v2-beta"`
+	SlugBuilderImage              string `envconfig:"SLUGBUILDER_IMAGE_NAME" required:"true"`
+	DockerBuilderImage            string `envconfig:"DOCKERBUILDER_IMAGE_NAME" required:"true"`
 	SlugBuilderImagePullPolicy    string `envconfig:"SLUG_BUILDER_IMAGE_PULL_POLICY" default:"Always"`
 	DockerBuilderImagePullPolicy  string `envconfig:"DOCKER_BUILDER_IMAGE_PULL_POLICY" default:"Always"`
 	StorageType                   string `envconfig:"BUILDER_STORAGE" default:"minio"`