Docker uses link to establish a connection between containers _docker

When using Docker, we often encounter the application that I need two or more containers, some of which need to use the services provided by other containers. For example, we need a container to provide MySQL database services, while the other two containers are connected as clients to use the MySQL database service. Let's take a look at how Docker through link to achieve this function.

1. Here we first create two container image, one to simulate the MySQL database, another to use the MySQL client to simulate some use of MySQL service applications, this application can be any Php,python,java applications.

1.1 First create a mysql_server directory and create a dockerfile file under it, as follows

From CENTOS:CENTOS6
maintainer fanbin Kong "kongxx@hotmail.com"

run yum install-y mysql-server MySQL

run/ Etc/init.d/mysqld start &&\
 mysql-e "grant all privileges on *.* to ' root ' @ '% ' identified by ' letmein ';" &&\
 MYSQL-E "grant all privileges on *.* to ' root ' @ ' localhost ' identified by ' letmein ';" &&\
 mysql-u root-pletmein-e "show databases;"

Expose 3306

CMD ["/usr/bin/mysqld_safe"]

And then based on Dockerfile to create the image

sudo docker build-t kongxx/mysql_server.

1.2 Create a mysql_client directory and create a dockerfile file under it, as follows

From CENTOS:CENTOS6
maintainer fanbin Kong "kongxx@hotmail.com"



RUN yum install-y MySQL

And then based on Dockerfile to create the image

sudo docker build-t kongxx/mysql_client.

1.3 After the image is created, we can use the following command to view the results

$ sudo docker images | grep kongxx
kongxx/mysql_client latest  aa31f22f6fc5 2 hours ago  303.7 MB
kongxx/mysql_server Latest  3b9b08c8dda4 2 hours ago  353.3 MB

2. The second step is to create our application scenario based on image

2.1 First create a container that provides MySQL database services

sudo docker run--name=mysql_server-d-P kongxx/mysql_server

2.2 Create two separate containers that use the previous step to create a MySQL database service

First Application Container

Copy Code code as follows:

sudo docker run--name=mysql_client1--link=mysql_server:db-t-i kongxx/mysql_client/usr/bin/mysql-h db-u root-pletme In

Second Application container

Copy Code code as follows:

sudo docker run--name=mysql_client2--link=mysql_server:db-t-i kongxx/mysql_client/usr/bin/mysql-h db-u root-pletme In

Here you need to pay special attention to "–link=mysql_server:db", which tells the Docker container to use the "Mysql_server" container and name its alias db so that you can use "db" in both containers As the name of the machine that provides the MySQL database service. So in the final boot parameters we use the "/usr/bin/mysql-h db-u Root-pletmein" to connect to the MySQL database.

2.3 After running the above two commands, we will create two MySQL client containers, at which point we can use the following command to view the status

sudo docker PS
CONTAINER ID IMAGE   COMMAND  CREATED  STATUS  PORTS   NAMES
ac0c76c627c0 Kongxx/mysql_client:latest/usr/bin/mysql-h db seconds ago up 9 seconds     Mysql_client2
763c4825722d kongxx/ Mysql_client:latest/usr/bin/mysql-h db minutes ago up minutes     mysql_client
32f7839f7e9d kongxx/mysql_ Server:latest/usr/bin/mysqld_safe about a hour ago up about a hour 0.0.0.0:49153->3306/tcp Mysql_client1/db,mysql_c Lient2/db,mysql_server 0.0.0.0:49153->3306/tcp Mysql_client1/db,mysql_client2/db,mysql_server

Notice here that the last line, the "NAMES" column of the Mysql_server container, is "mysql_client/db,mysql_client2/db,mysql_server", which means that mysql_ Client1 and Mysql_client2 are connected to db.

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