Basic boilerplate for creating a connection from a Node container to a MySql Container.
Opening a success TCP connection from a Node container to a MySQL container can be very frustrating if you are not experienced with docker networks or understand how they configure your containers to begin communications between each other.
Run with
docker-compose up --buildSome Important Notes For Understanding
- Docker Containers by default are completely isolated and have no idea of other Containers running via Docker.
- Docker Compose versions like '3' automatically define a default network and add it to each one of your services.
- Stop using Localhost or 127.0.0.1 as your hostname and address when making a connection within a container. Instead, use your docker service name. Docker uses the name of these services has the hostname in the docker host and maps that to the correct address assuming a network has been configured.
- The only time you should use localhost is when connecting to a container is via the host.
mysql -h 127.0.0.1 -u root -proot -P 3306- MySQL needs a socket connection or a TCP connection. the protocol option with correctly map localhost to 127.0.0.1.
mysql -h localhost --protocol=tcp -u root -proot -P 3306- Avoid the mysql image 'mysql:latest' because of authentication changes and support is lacking.
- A 'Health Check' or a bash script that checks the status of mysql before starting your node application (dbwait-script.sh) is needed to insure your database is ready to start accepting connections. Read here for more infomation.
const db = mysql.createConnection({
host: process.env.MYSQL_CONTAINER_NAME,
port: process.env.MYSQL_PORT,
user: process.env.MYSQL_USER,
password: process.env.MYSQL_ROOT_PASSWORD,
});