new: redirect standard logs towards stderr if running an action

This allows direct actions to produce output that won't be messed
around by the logs.

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

bin/compose-core

@@ -3850,6 +3850,10 @@ fi
 _setup_state_dir
 mkdir -p "$CACHEDIR" || exit 1
 
+
+log () { cat; }
+export -f log
+
 ##
 ## Argument parsing
 ##
@@ -3887,6 +3891,8 @@ while read-0 arg; do
                 --quiet|-q)
                     export QUIET=true
                     export wrap_opts+=("-q")
+                    log () { cat >&2; }
+                    export -f log
                     ;;
                 --version|-V)
                     print_version
@@ -4081,6 +4087,10 @@ if [ -z "$is_docker_compose_action" -a "$action" ]; then
             esac
         } < <(has_service_action "$action_service" "$action")
         services_args=("$action_service")
+
+        ## Divert logging to stdout to stderr
+        log () { cat >&2; }
+        export -f log
     else
         die "Unknown action '${DARKCYAN}$action$NORMAL': It doesn't match any docker-compose commands nor inner charm actions."
     fi
@@ -4185,7 +4195,7 @@ if [ -n "$full_init" ]; then
 
     run_service_hook pre_deploy "${services_args[@]}" || exit 1
 
-fi
+fi | log
 
 if [ "$action" == "run" -a "${#services_args}" != 0 ]; then
     charm=$(get_service_charm "${services_args[0]}") || exit 1