Add support for passing a file path as the value for WORDPRESS_DB_PASSWORD

Allows use of Docker secrets to store these credentials.
If the secret has been granted to the container, the
password will be available within the container as
an unencrypted string in /run/secrets/.

Signed-off-by: Misty Stanley-Jones <[email protected]>

Author: Misty Stanley-Jones

docker-entrypoint.sh

@@ -10,7 +10,12 @@ if [[ "$1" == apache2* ]] || [ "$1" == php-fpm ]; then
 	fi
 	: ${WORDPRESS_DB_PASSWORD:=$MYSQL_ENV_MYSQL_PASSWORD}
 	: ${WORDPRESS_DB_NAME:=${MYSQL_ENV_MYSQL_DATABASE:-wordpress}}
-
+  # If the value of WORDPRESS_DB_PASSWORD is a file that exists within
+  # the container, read the contents of that file (useful if using
+  # Docker-managed secrets)
+  if [ -f "$WORDPRESS_DB_PASSWORD" ]; then
+    WORDPRESS_DB_PASSWORD="$(cat $WORDPRESS_DB_PASSWORD)"
+  fi
 	if [ -z "$WORDPRESS_DB_PASSWORD" ]; then
 		echo >&2 'error: missing required WORDPRESS_DB_PASSWORD environment variable'
 		echo >&2 '  Did you forget to -e WORDPRESS_DB_PASSWORD=... ?'