expose

用於 container 跟 container 之間的 port 的溝通，也就是說定義 expose 的 port 號只能被其他 container 存取，不能被 host 也就是外部存取

啟動 mysql 作為 server

docker run -d \
--name mysql-server \
-e MYSQL_ROOT_PASSWORD="pass" \
--expose 3306 \
mysql

執行 docker ps

將會看到下面結果，可以看到 ports 為 3306/tcp

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
5af9391204b2        mysql    "/run.sh"           4 seconds ago       Up 3 seconds        3306/tcp            mysql-server

啟動 mysql 作為 client

注意：須等待 mysql-server 啟動完成，估計需要 30 ~ 60 秒

docker run -it --rm \
--name mysql-client \
--link mysql-server \
mysql \
mysql -uadmin -h mysql-server -ppass

將會看到 mysql 已正確連接

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.5.47-0ubuntu0.14.04.1 (Ubuntu)

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