How to connect localhost:3306 of mysql container v

Question

In my application setting I am connecting to db with below settings

spring.jpa.hibernate.ddl-auto=none
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/gosallowMultiQueries=true&createDatabaseIfNotExist=true
spring.datasource.username=root
spring.datasource.password=root

Now I have two container App and mysql. I have linked both container

docker run --name app --link mysql:dbalias appimage

but I am getting Communications link failure error. I am not able to connect with mysql server

I used below command to run mysql container:

docker run --name mysql -e MYSQL_ROOT_PASSWORD=root -d -p 3306:3306 mysql:latest

Any suggestion?

Answer 1

You are pointing to localhost which means the app is trying to connect to localhost of it's own container. NOT the localhost of your host.

If those 2 containers are deployed inside the same user defined bridge network you can can communicate using container names:

spring.datasource.url=jdbc:mysql://mysql:3306/gosallowMultiQueries=true&createDatabaseIfNotExist=true

if they aren't you can use the container IP of the mysql container but this can change when the container restarts/is recreated. The recommended approach is to create a user defined bridge network:

$ docker network create my-network
$ docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
73df63463bb2        bridge              bridge              local
4cabe965c01d        host                host                local
c94ae182d8fa        my-network          bridge              local
93ec6f5bf028        none                null                local

and start your two containers inside the same network:

$ docker run --name mysql --network=my-network -e MYSQL_ROOT_PASSWORD=root -d -p 3306:3306 mysql:latest

When both containers are started inside the same user defined network you can communicate using container name (you can test by docker exec inside one of the containers and try to ping the other one using the container name).