Added a way to store root password in a file

If the MYSQL_ROOT_PASSWORD variable is a valid file path, the entrypoint
script will cat the file and use the output as the root password.

Author: ltangvald

5.5/docker-entrypoint.sh

@@ -12,10 +12,14 @@ if [ "$1" = 'mysqld' ]; then
 
 	if [ ! -d "$DATADIR/mysql" ]; then
 		if [ -z "$MYSQL_ROOT_PASSWORD" -a -z "$MYSQL_ALLOW_EMPTY_PASSWORD" -a -z "$MYSQL_RANDOM_ROOT_PASSWORD" ]; then
-                        echo >&2 'error: database is uninitialized and password option is not specified '
-                        echo >&2 '  You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD'
-                        exit 1
-                fi
+			echo >&2 'error: database is uninitialized and password option is not specified '
+			echo >&2 '  You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD'
+			exit 1
+		fi
+		# If the password variable is a filename we use the contents of the file
+		if [ -f "$MYSQL_ROOT_PASSWORD" ]; then
+			MYSQL_ROOT_PASSWORD="$(cat $MYSQL_ROOT_PASSWORD)"
+		fi
 		mkdir -p "$DATADIR"
 		chown -R mysql:mysql "$DATADIR"
 

5.6/docker-entrypoint.sh

@@ -12,10 +12,14 @@ if [ "$1" = 'mysqld' ]; then
 
 	if [ ! -d "$DATADIR/mysql" ]; then
 		if [ -z "$MYSQL_ROOT_PASSWORD" -a -z "$MYSQL_ALLOW_EMPTY_PASSWORD" -a -z "$MYSQL_RANDOM_ROOT_PASSWORD" ]; then
-                        echo >&2 'error: database is uninitialized and password option is not specified '
-                        echo >&2 '  You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD'
-                        exit 1
-                fi
+			echo >&2 'error: database is uninitialized and password option is not specified '
+			echo >&2 '  You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD'
+			exit 1
+		fi
+		# If the password variable is a filename we use the contents of the file
+		if [ -f "$MYSQL_ROOT_PASSWORD" ]; then
+			MYSQL_ROOT_PASSWORD="$(cat $MYSQL_ROOT_PASSWORD)"
+		fi
 		mkdir -p "$DATADIR"
 		chown -R mysql:mysql "$DATADIR"
 

5.7/docker-entrypoint.sh

@@ -16,6 +16,10 @@ if [ "$1" = 'mysqld' ]; then
 			echo >&2 '  You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD'
 			exit 1
 		fi
+		# If the password variable is a filename we use the contents of the file
+		if [ -f "$MYSQL_ROOT_PASSWORD" ]; then
+			MYSQL_ROOT_PASSWORD="$(cat $MYSQL_ROOT_PASSWORD)"
+		fi
 		mkdir -p "$DATADIR"
 		chown -R mysql:mysql "$DATADIR"