How to Fix 'Communications Link Failure” Errors When Connecting to MySQL in a Dockerized Spring Boot Application?

Communications Link Failure in Spring Boot, MySQL, Docker, and Hibernate

Problem:
When running a Spring Boot application with Hibernate and MySQL using Docker Compose, an error occurs with the following message:

Communications link failure
java.net.ConnectException: Connection refused

Details:
The error occurs when the application tries to establish a connection to the MySQL database. The connection URL in jdbc:mysql://localhost/database refers to the local host, which is not the correct address within the Docker container.

Solution:
To resolve this issue, the connection URL in the JDBC connection and the Spring Boot configuration (application.properties) should be updated to point to the MySQL container's address.

JDBC Connection:

<code class="java">private Connection createConnection() throws SQLException {
    DriverManager.registerDriver(new com.mysql.jdbc.Driver());
    String mysqlUrl = "jdbc:mysql://docker-mysql:3306/database?autoReconnect=true&useSSL=false";
    Connection connection = DriverManager.getConnection(mysqlUrl, "root", "root");
    return connection;
}</code>

Spring Boot Configuration (application.properties):

<code class="properties">spring.datasource.url=jdbc:mysql://docker-mysql:3306/database?autoReconnect=true&useSSL=false
spring.datasource.username=root
spring.datasource.password=root</code>

Docker Compose Configuration (docker-compose.yml):
Ensure that the Docker Compose configuration correctly defines the port mapping for the MySQL container:

<code class="yaml">services:
  docker-mysql:
    image: mysql:5.7
    ports:
      - 3307:3306</code>

and that the application container depends on the MySQL container:

<code class="yaml">app:
    image: app:latest
    ports:
      - 8091:8091
    depends_on:
      - docker-mysql</code>

The above is the detailed content of How to Fix 'Communications Link Failure” Errors When Connecting to MySQL in a Dockerized Spring Boot Application?. For more information, please follow other related articles on the PHP Chinese website!