with command

entrypoint.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+set -e
+
+file_env() {
+   local var="$1"
+   local fileVar="${var}_FILE"
+   local def="${2:-}"
+
+   if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
+      echo >&2 "error: both $var and $fileVar are set (but are exclusive)"
+      exit 1
+   fi
+
+   local val="$def"
+
+   if [ "${!var:-}" ]; then
+      val="${!var}"
+   elif [ "${!fileVar:-}" ]; then
+      val="$(< "${!fileVar}")"
+   fi
+
+   export "$var"="$val"
+   unset "$fileVar"
+}
+
+
+file_env "database__connection__password"
+file_env "mail__options__auth__pass"
+
+# upstream entrypoint https://github.com/docker-library/ghost/blob/master/5/alpine/Dockerfile
+/usr/local/bin/docker-entrypoint.sh "$@"