new: add ``SHOW_ENV`` and ``SHOW_CONFIG_LOCATIONS``

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

bin/compose

@@ -921,24 +921,10 @@ mk_docker_run_options() {
     mkdir -p "$SESSION_DIR" || return 1
     mv -f "$filename" "$src" || return 1
 
-    if [ -n "$DEBUG" ]; then
-        echo "${WHITE}Environment:${NORMAL}"
-        echo "  COMPOSE_DOCKER_IMAGE: $COMPOSE_DOCKER_IMAGE"
-        echo "  CHARM_STORE: $CHARM_STORE"
-        echo "  DATASTORE: $DATASTORE"
-        echo "  CONFIGSTORE: $CONFIGSTORE"
-        echo "  COMPOSE_VAR: $COMPOSE_VAR"
-        echo "  COMPOSE_CACHE: $COMPOSE_CACHE"
-        echo "  COMPOSE_LAUNCHER_CACHE: $COMPOSE_LAUNCHER_CACHE"
-        echo "  SESSION_DIR: $SESSION_DIR"
-        echo "  TZ_PATH: $TZ_PATH"
-    fi >&2
 }
 
 
-run() {
-    local os docker_run_opts
-
+load_env() {
     docker_run_opts=()
     if [ -z "$COMPOSE_LAUNCHER_OPTS" ]; then
         mk_docker_run_options "$@" || return 1
@@ -955,8 +941,29 @@ run() {
             fi
         done < <(cat "$COMPOSE_LAUNCHER_OPTS")
     fi
+}
+
+show_env() {
+    echo "${WHITE}Environment:${NORMAL}"
+    echo "  COMPOSE_DOCKER_IMAGE: $COMPOSE_DOCKER_IMAGE"
+    echo "  CHARM_STORE: $CHARM_STORE"
+    echo "  DATASTORE: $DATASTORE"
+    echo "  CONFIGSTORE: $CONFIGSTORE"
+    echo "  COMPOSE_VAR: $COMPOSE_VAR"
+    echo "  COMPOSE_CACHE: $COMPOSE_CACHE"
+    echo "  COMPOSE_LAUNCHER_CACHE: $COMPOSE_LAUNCHER_CACHE"
+    echo "  SESSION_DIR: $SESSION_DIR"
+    echo "  TZ_PATH: $TZ_PATH"
+}
+
 
-    set_os
+run() {
+    local os docker_run_opts
+    load_env "$@" || return 1
+
+    [ -n "$DEBUG" ] && show_env
+
+    set_os || return 1
 
     if [ -n "$ARG_COMPOSE_FILE" ]; then
         array_read-0 cmd_args < \
@@ -1006,4 +1013,19 @@ depends docker cat readlink sed realpath tee sed grep tail
 
 ansi_color "${ansi_color:-tty}"
 
+if [ "$SHOW_ENV" ]; then
+    load_env || return 1
+    show_env
+    exit 0
+fi
+
+if [ "$SHOW_CONFIG_LOCATIONS" ]; then
+    set_os || return 1
+    echo "compose will read these files if existing in the given order:"
+    for loc in "${compose_config_files[@]}"; do
+        echo " - $loc"
+    done
+    exit 0
+fi
+
 run "$@"