--- a/taskcluster/taskgraph/docker.py
+++ b/taskcluster/taskgraph/docker.py
@@ -72,21 +72,31 @@ def build_image(name):
     """
     if not name:
         raise ValueError('must provide a Docker image name')
 
     image_dir = os.path.join(IMAGE_DIR, name)
     if not os.path.isdir(image_dir):
         raise Exception('image directory does not exist: %s' % image_dir)
 
+    tag = docker.docker_image(name, default_version='latest')
+
     docker_bin = which.which('docker')
 
     # Verify that Docker is working.
     try:
         subprocess.check_output([docker_bin, '--version'])
     except subprocess.CalledProcessError:
         raise Exception('Docker server is unresponsive. Run `docker ps` and '
                         'check that Docker is running')
 
-    args = [os.path.join(IMAGE_DIR, 'build.sh'), name]
+    args = [os.path.join(IMAGE_DIR, 'build.sh'), name, tag]
     res = subprocess.call(args, cwd=IMAGE_DIR)
     if res:
         raise Exception('error building image')
+
+    if tag.endswith(':latest'):
+        print('*' * 50)
+        print('WARNING: no VERSION file found in image directory.')
+        print('Image is not suitable for deploying/pushing.')
+        print('Create an image suitable for deploying/pushing by creating')
+        print('a VERSION file in the image directory.')
+        print('*' * 50)

--- a/taskcluster/taskgraph/util/docker.py
+++ b/taskcluster/taskgraph/util/docker.py
@@ -13,28 +13,34 @@ from mozpack.archive import (
 )
 
 
 GECKO = os.path.realpath(os.path.join(__file__, '..', '..', '..', '..'))
 DOCKER_ROOT = os.path.join(GECKO, 'testing', 'docker')
 ARTIFACT_URL = 'https://queue.taskcluster.net/v1/task/{}/artifacts/{}'
 
 
-def docker_image(name):
+def docker_image(name, default_version=None):
     '''Determine the docker image name, including repository and tag, from an
     in-tree docker file.'''
     try:
         with open(os.path.join(DOCKER_ROOT, name, 'REGISTRY')) as f:
             registry = f.read().strip()
     except IOError:
         with open(os.path.join(DOCKER_ROOT, 'REGISTRY')) as f:
             registry = f.read().strip()
 
-    with open(os.path.join(DOCKER_ROOT, name, 'VERSION')) as f:
-        version = f.read().strip()
+    try:
+        with open(os.path.join(DOCKER_ROOT, name, 'VERSION')) as f:
+            version = f.read().strip()
+    except IOError:
+        if not default_version:
+            raise
+
+        version = default_version
 
     return '{}/{}:{}'.format(registry, name, version)
 
 
 def generate_context_hash(topsrcdir, image_path, image_name):
     """Generates a sha256 hash for context directory used to build an image."""
 
     # It is a bit unfortunate we have to create a temp file here - it would

--- a/testing/docker/build.sh
+++ b/testing/docker/build.sh
@@ -1,79 +1,26 @@
 #! /bin/bash -e
 
 # This file is a wrapper around docker build with specific concerns around image
 # versions and registry deployment... It also attempts to detect any potential
 # missing dependencies and warns you about them.
 
 gecko_root="$( cd "$( dirname "${BASH_SOURCE[0]}" )/../.." && pwd )"
 
-usage() {
-  echo "Build a docker image (and tag it)"
-  echo
-  echo "$0 <image-name>"
-  echo
-  echo "  Images are defined in testing/docker/<image-name>."
-  echo "  For more see: $PWD/README.md"
-  echo
-}
-
-usage_err() {
-  echo $1
-  echo
-  usage
-  exit 1
-}
-
 build() {
   local image_name=$1
+  local tag=$2
   local folder="$gecko_root/testing/docker/$image_name"
-  local folder_reg="$folder/REGISTRY"
-  local folder_ver="$folder/VERSION"
-  local could_deploy=false
-
-  # Assume that if an image context directory does not contain a VERSION file then
-  # it is not suitable for deploying.  Default to using 'latest' as the tag and
-  # warn the user at the end.
-  if [ ! -f $folder_ver ]; then
-    echo "This image does not contain a VERSION file.  Will use 'latest' as the image version"
-    local tag="$image_name:latest"
-  else
-    local version=$(cat $folder_ver)
-    test -n "$version" || usage_err "$folder_ver is empty aborting..."
-
-    # Fallback to default registry if one is not in the folder...
-    if [ ! -f "$folder_reg" ]; then
-      folder_reg=$PWD/REGISTRY
-    fi
-
-    local registry=$(cat $folder_reg)
-    test -n "$registry" || usage_err "$folder_reg is empty aborting..."
-
-    local tag="$registry/$image_name:$version"
-    local could_deploy=true
-  fi
 
   if [ -f $folder/build.sh ]; then
     shift
     $folder/build.sh -t $tag $* || exit 1
   else
     # use --no-cache so that we always get the latest updates from yum
     # and use the latest version of system-setup.sh
     ( cd $folder/.. && docker build --no-cache -t $tag $image_name ) || exit 1
   fi
 
   echo "Success built $image_name and tagged with $tag"
-  if [ "$could_deploy" = true ]; then
-    echo "If deploying now you can run 'docker push $tag'"
-  else
-    echo "*****************************************************************"
-    echo "WARNING: No VERSION file was found in the image directory."
-    echo "Image has not been prepared for deploying at this time."
-    echo "However, the image can be run locally. To prepare to "
-    echo "push to a user account on a docker registry, tag the image "
-    echo "by running 'docker tag $tag [REGISTRYHOST/][USERNAME/]NAME[:TAG]"
-    echo "prior to running 'docker push'."
-    echo "*****************************************************************"
-  fi
 }
 
 build $*