apply tags on each run

Author: jameslnewell

README.md

@@ -293,7 +293,7 @@ steps:
 
 ### Specifying tags to apply to the pushed Docker image
 
-By default, the image is tagged with the `latest` tag in addition to the cache key.
+The image is tagged with the cache key and`latest`.
 
 By specifying the `tags` parameter you can specify your own set of tags to apply to the image:
 
@@ -303,11 +303,10 @@ steps:
     plugins:
       - seek-oss/docker-ecr-cache#v2.0.0:
           tags:
-            - latest
             - build-${BUILDKITE_BUILD_NUMBER}
 ```
 
-Specifying your own tags makes it easy to reuse the image later in the pipeline.
+These tags are applied *each time the plugin runs*, whether the image is newly built or already exists and was pulled.
 
 ### AWS ECR specific configuration
 

hooks/pre-command

@@ -71,26 +71,26 @@ if ! docker pull "${image}:${tag}"; then
   docker "${image_build_args[@]}" ${BUILDKITE_PLUGIN_DOCKER_ECR_CACHE_ADDITIONAL_BUILD_ARGS:-} "${context}" ||
     log_fatal "^^^ +++" 1
 
-  echo "--- Pushing tags"
-  echo " - ${tag}"
-  docker push "${image}:${tag}"
+  docker tag "${image}:${tag}" "${image}:latest"
 
-  results=()
-  read_list_property 'TAGS'
-  if [ "${#result[*]}" == "0" ]; then
-    echo " - latest"
-    docker tag "${image}:${tag}" "${image}:latest"
-    docker push "${image}:latest"
-  else
-    for other_tag in ${result[@]+"${result[@]}"}; do
-      echo " - ${other_tag}"
-      docker tag "${image}:${tag}" "${image}:${other_tag}"
-      docker push "${image}:${other_tag}"
-    done
-  fi
+  echo "--- Pushing tag ${tag}"
+  docker push "${image}:${tag}"
 
+  echo "--- Pushing tag latest"
+  docker push "${image}:latest"
 fi || echo "Not found"
 
+results=()
+read_list_property 'TAGS'
+if [ "${#result[*]}" != "0" ]; then
+  for extra_tag in ${result[@]+"${result[@]}"}; do
+    echo "--- Pushing extra tags"
+    echo " - ${extra_tag}"
+    docker tag "${image}:${tag}" "${image}:${extra_tag}"
+    docker push "${image}:${extra_tag}"
+  done
+fi
+
 # Support using https://github.com/buildkite-plugins/docker-buildkite-plugin without an image by default
 export ${export_env_variable}="${image}:${tag}"