Styjun

I checked many forum entries (e.g. in stackoverflow too) but I still cannot figure out what the problem is with my docker-compose file.

So when I start my application (content-app) I got the following exception:

Failed to obtain JDBC Connection; nested exception is java.sql.SQLNonTransientConnectionException: Could not connect to address=(host=content-database)(port=3306)(type=master) : Connection refused (Connection refused)

My application is a Spring boot app that tries to connect to the database, the JDBC URL is

url: jdbc:mariadb://content-database:3306/contentdb?autoReconnect=true

The Spring Boot app works fine as locally (when no docker is used) can connect to the local mariadb.

So the content-app container don't see the content-database container. I read that if I specify a network and I assign the containers to the network then they should be able to connect to each other.

When I connect to the running content-app container then I can telnet to content-database

root@894628d7bdd9:/# telnet content-database 3306
Trying 172.28.0.3...
Connected to content-database.
Escape character is '^]'.
n
5.5.5-10.4.3-MariaDB-1:10.4.3+maria~bionip/4X@wW/�#_9<b[~)N.:ymysql_native_passwordConnection closed by foreign host.

My docker-compose yaml file:

version: '3.3'
networks: 
 net_content:
services:
 content-database:
 image: content-database:latest
 build:
 context: .
 dockerfile: ./database/Dockerfile 
 networks: 
 - net_content
 restart: always
 environment:
 MYSQL_ROOT_PASSWORD: root
 content-redis:
 image: content-redis:latest
 build:
 context: .
 dockerfile: ./redis/Dockerfile 
 networks: 
 - net_content
 content-app:
 image: content-app:latest
 build:
 context: .
 dockerfile: ./content/Dockerfile 
 networks: 
 - net_content
 depends_on:
 - "content-database"

Any hint please?

Thanks!

I guess MariaDB is listening on default port 3307, this means your application has to connect to this port as well. I guess this is the case as you are mapping the port 3307 of your container to "the outside".

Change the port in your connection string:

url: jdbc:mariadb://content-database:3307/contentdb?autoReconnect=true

You have to expose the port on which content-database is listening in the Dockerfile at ./database/Dockerfile