Resync entrypoint features from MySQL

Especially docker-library/mysql#249 and docker-library/mysql#266.

Author: tianon

docker-entrypoint.sh

@@ -54,14 +54,18 @@ _check_config() {
 	fi
 }
 
-_datadir() {
-	"$@" --verbose --help --log-bin-index="$(mktemp -u)" 2>/dev/null | awk '$1 == "datadir" { print $2; exit }'
+# Fetch value from server config
+# We use mysqld --verbose --help instead of my_print_defaults because the
+# latter only show values present in config files, and not server defaults
+_get_config() {
+	local conf="$1"; shift
+	"$@" --verbose --help --log-bin-index="$(mktemp -u)" 2>/dev/null | awk '$1 == "'"$conf"'" { print $2; exit }'
 }
 
 # allow the container to be started with `--user`
 if [ "$1" = 'mysqld' -a -z "$wantHelp" -a "$(id -u)" = '0' ]; then
 	_check_config "$@"
-	DATADIR="$(_datadir "$@")"
+	DATADIR="$(_get_config 'datadir' "$@")"
 	mkdir -p "$DATADIR"
 	chown -R mysql:mysql "$DATADIR"
 	exec gosu mysql "$BASH_SOURCE" "$@"
@@ -71,7 +75,7 @@ if [ "$1" = 'mysqld' -a -z "$wantHelp" ]; then
 	# still need to check config, container may have started with --user
 	_check_config "$@"
 	# Get config
-	DATADIR="$(_datadir "$@")"
+	DATADIR="$(_get_config 'datadir' "$@")"
 
 	if [ ! -d "$DATADIR/mysql" ]; then
 		file_env 'MYSQL_ROOT_PASSWORD'
@@ -87,10 +91,11 @@ if [ "$1" = 'mysqld' -a -z "$wantHelp" ]; then
 		mysql_install_db --datadir="$DATADIR" --rpm
 		echo 'Database initialized'
 
-		"$@" --skip-networking --socket=/var/run/mysqld/mysqld.sock &
+		SOCKET="$(_get_config 'socket' "$@")"
+		"$@" --skip-networking --socket="${SOCKET}" &
 		pid="$!"
 
-		mysql=( mysql --protocol=socket -uroot -hlocalhost --socket=/var/run/mysqld/mysqld.sock )
+		mysql=( mysql --protocol=socket -uroot -hlocalhost --socket="${SOCKET}" )
 
 		for i in {30..0}; do
 			if echo 'SELECT 1' | "${mysql[@]}" &> /dev/null; then
@@ -113,14 +118,28 @@ if [ "$1" = 'mysqld' -a -z "$wantHelp" ]; then
 			export MYSQL_ROOT_PASSWORD="$(pwgen -1 32)"
 			echo "GENERATED ROOT PASSWORD: $MYSQL_ROOT_PASSWORD"
 		fi
+
+		rootCreate=
+		# default root to listen for connections from anywhere
+		file_env 'MYSQL_ROOT_HOST' '%'
+		if [ ! -z "$MYSQL_ROOT_HOST" -a "$MYSQL_ROOT_HOST" != 'localhost' ]; then
+			# no, we don't care if read finds a terminating character in this heredoc
+			# https://unix.stackexchange.com/questions/265149/why-is-set-o-errexit-breaking-this-read-heredoc-expression/265151#265151
+			read -r -d '' rootCreate <<-EOSQL || true
+				CREATE USER 'root'@'${MYSQL_ROOT_HOST}' IDENTIFIED BY '${MYSQL_ROOT_PASSWORD}' ;
+				GRANT ALL ON *.* TO 'root'@'${MYSQL_ROOT_HOST}' WITH GRANT OPTION ;
+			EOSQL
+		fi
+
 		"${mysql[@]}" <<-EOSQL
 			-- What's done in this file shouldn't be replicated
 			--  or products like mysql-fabric won't work
 			SET @@SESSION.SQL_LOG_BIN=0;
 
-			DELETE FROM mysql.user ;
-			CREATE USER 'root'@'%' IDENTIFIED BY '${MYSQL_ROOT_PASSWORD}' ;
-			GRANT ALL ON *.* TO 'root'@'%' WITH GRANT OPTION ;
+			DELETE FROM mysql.user WHERE user NOT IN ('mysql.sys', 'mysqlxsys', 'root') OR host NOT IN ('localhost') ;
+			SET PASSWORD FOR 'root'@'localhost'=PASSWORD('${MYSQL_ROOT_PASSWORD}') ;
+			GRANT ALL ON *.* TO 'root'@'localhost' WITH GRANT OPTION ;
+			${rootCreate}
 			DROP DATABASE IF EXISTS test ;
 			FLUSH PRIVILEGES ;
 		EOSQL