Update hook with proper build vars

Author: andrewnicols

hooks/post_push

@@ -5,12 +5,11 @@ set -e
 # A space-separated list of additional tags to place on this image.
 additionalTags=(7.1 71 7.1-jessie 71-jessie)
 
-# Parse image name for repo name.
-tagStart=$(expr index "$IMAGE_NAME" :)
-repoName=${IMAGE_NAME:1:tagStart-1}
-
 # Tag and push image for each additional tag
 for tag in ${additionalTags[@]}; do
-    docker tag $IMAGE_NAME ${repoName}:${tag}
-    docker push ${repoName}:${tag}
+    echo "Tagging {$IMAGE_NAME} as ${DOCKER_REPO}:${tag}"
+    docker tag $IMAGE_NAME ${DOCKER_REPO}:${tag}
+
+    echo "Pushing ${DOCKER_REPO}:${tag}"
+    docker push ${DOCKER_REPO}:${tag}
 done