new: added labels to attach important information from compose on running containers.

bin/compose

@@ -773,6 +773,11 @@ _get_docker_compose_service_mixin() {
 
     ## The compose part
 
+    base_mixin="$master_charm:
+  labels:
+   - \"compose.service=$service\"
+   - \"compose.master-charm=${master_charm}\"
+   - \"compose.project=$(get_default_project_name)\""
     links_yaml=$(get_docker_compose_links "$service") || return 1
     docker_compose_options=$(_get_docker_compose_opts "$service") || return 1
 
@@ -785,9 +790,9 @@ _get_docker_compose_service_mixin() {
     ## Merge results
     if [ "$charm_part" ]; then
         charm_yaml="$(yaml_key_val_str "$master_charm" "$charm_part")" || return 1
-        merge_yaml_str "$links_yaml" "$charm_yaml" "$docker_compose_options" || return 1
+        merge_yaml_str "$base_mixin" "$links_yaml" "$charm_yaml" "$docker_compose_options" || return 1
     else
-        echo "$links_yaml"
+        merge_yaml_str "$base_mixin" "$links_yaml" "$docker_compose_options" || return 1
     fi | tee "$cache_file"
     if [ "${PIPESTATUS[0]}" != 0 ]; then
         rm "$cache_file"
@@ -1885,7 +1890,7 @@ _get_docker_compose_mixin_from_metadata_cached() {
         return 0
     fi
 
-    mixin=
+    mixin=$(echo -en "labels:\n - \"compose.charm=$charm\"")
     if [ "$metadata" ]; then
         ## resources to volumes
         volumes=$(
@@ -1910,7 +1915,11 @@ _get_docker_compose_mixin_from_metadata_cached() {
             done < <(echo "$metadata" | shyaml get-values-0 "charm-resources" 2>/dev/null)
                ) || return 1
         if [ "$volumes" ]; then
-            mixin=$(echo -en "volumes:\n$volumes")
+            mixin=$(merge_yaml_str "$mixin" "$(echo -en "volumes:\n$volumes")") || {
+                err "Failed to merge mixin with ${WHITE}docker-compose${NORMAL} option" \
+                    "from charm ${DARKYELLOW}$charm$NORMAL."
+                return 1
+            }
         fi
 
         docker_compose=$(echo "$metadata" | shyaml get-value -y "docker-compose" 2>/dev/null)