Add the ability to use secrets for credentials

entrypoint.sh

@@ -1,6 +1,35 @@
 #!/usr/bin/env bash
 set -e
 
+# usage: file_env VAR [DEFAULT]
+# ie: file_env 'XYZ_DB_PASSWORD' 'example'
+# (will allow for "$XYZ_DB_PASSWORD_FILE" to fill in the value of
+# "$XYZ_DB_PASSWORD" from a file, especially for Docker's secrets feature)
+file_env() {
+ local var="$1"
+ local fileVar="${var}_FILE"
+ local def="${2:-}"
+ if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
+ echo >&2 "error: both ${varName} and ${fileVarName} are set (but are exclusive)"
+ exit 1
+ fi
+ local val="$def"
+ if [ "${!var:-}" ]; then
+ val="${!var}"
+ elif [ "${!fileVar:-}" ]; then
+ val="$(< "${!fileVar}")"
+ fi
+ export "$var"="$val"
+ unset "$fileVar"
+}
+
+file_env GMAIL_USER
+file_env GMAIL_PASSWORD
+file_env SES_USER
+file_env SES_PASSWORD
+file_env SMARTHOST_USER
+file_env SMARTHOST_PASSWORD
+
 # Initialize localmacros as an empty file
 echo -n "" > /etc/exim4/exim4.conf.localmacros