Docker官方的MySQL镜像的Dockerfile托管在Github上，地址如下：
https://github.com/docker-library/mysql/tree/5836bc9af9deb67b68c32bebad09a0f7513da36e/5.6
仔细研究了一下其Dockerfile，发现最有技术含量的倒不是其Dockerfile本身，无非是更新软件仓库，下载Mysql Server，稍微修改一下其配置文件。
倒是ENTRYPOINT对应的docker-entrypoint.sh很耐人寻味，这个文件相当详实，涉及了Mysql如何初始化，如何设置密码，如何启动服务等关键问题。
今天花费了大半天来分析这个脚本，果然是受益匪浅。
脚本及分析结果如下：
#!/bin/bash
set -e
# if command starts with an option, prepend mysqld
if [ "${1:0:1}" = '-' ]; then
set -- mysqld "$@"
fi
if [ "$1" = 'mysqld' ]; then
# Get config
DATADIR="$("$@" --verbose --help 2>/dev/null | awk '$1 == "datadir" { print $2; exit }')"
if [ ! -d "$DATADIR/mysql" ]; then
if [ -z "$MYSQL_ROOT_PASSWORD" -a -z "$MYSQL_ALLOW_EMPTY_PASSWORD" ]; then
echo >&2 'error: database is uninitialized and MYSQL_ROOT_PASSWORD not set'
echo >&2 ' Did you forget to add -e MYSQL_ROOT_PASSWORD=... ?'
exit 1
fi
mkdir -p "$DATADIR"
chown -R mysql:mysql "$DATADIR"
echo 'Running mysql_install_db'
mysql_install_db --user=mysql --datadir="$DATADIR" --rpm --keep-my-cnf
echo 'Finished mysql_install_db'
mysqld --user=mysql --datadir="$DATADIR" --skip-networking &
pid="$!"
mysql=( mysql --protocol=socket -uroot )
for i in {30..0}; do
if echo 'SELECT 1' | "${mysql[@]}" &> /dev/null; then
break
fi
echo 'MySQL init process in progress...'
sleep 1
done
if [ "$i" = 0 ]; then
echo >&2 'MySQL init process failed.'
exit 1
fi
# sed is for https://bugs.mysql.com/bug.php?id=20545
mysql_tzinfo_to_sql /usr/share/zoneinfo | sed 's/Local time zone must be set--see zic manual page/FCTY/' | "${mysql[@]}" mysql
"${mysql[@]}" <<-EOSQL
-- What's done in this file shouldn't be replicated
-- or products like mysql-fabric won't work
SET @@SESSION.SQL_LOG_BIN=0;
DELETE FROM mysql.user ;
CREATE USER 'root'@'%' IDENTIFIED BY '${MYSQL_ROOT_PASSWORD}' ;
GRANT ALL ON *.* TO 'root'@'%' WITH GRANT OPTION ;
DROP DATABASE IF EXISTS test ;
FLUSH PRIVILEGES ;
EOSQL
if [ ! -z "$MYSQL_ROOT_PASSWORD" ]; then
mysql+=( -p"${MYSQL_ROOT_PASSWORD}" )
fi
if [ "$MYSQL_DATABASE" ]; then
echo "CREATE DATABASE IF NOT EXISTS \`$MYSQL_DATABASE\` ;" | "${mysql[@]}"
mysql+=( "$MYSQL_DATABASE" )
fi
if [ "$MYSQL_USER" -a "$MYSQL_PASSWORD" ]; then
echo "CREATE USER '"$MYSQL_USER"'@'%' IDENTIFIED BY '"$MYSQL_PASSWORD"' ;" | "${mysql[@]}"
if [ "$MYSQL_DATABASE" ]; then
echo "GRANT ALL ON \`"$MYSQL_DATABASE"\`.* TO '"$MYSQL_USER"'@'%' ;" | "${mysql[@]}"
fi
echo 'FLUSH PRIVILEGES ;' | "${mysql[@]}"
fi
echo
for f in /docker-entrypoint-initdb.d/*; do
case "$f" in
*.sh) echo "$0: running $f"; . "$f" ;;
*.sql) echo "$0: running $f"; "${mysql[@]}" < "$f" && echo ;;
*) echo "$0: ignoring $f" ;;
esac
echo
done