mount mysql-db to docker-container - mysql

Question

I have this little node-app for testing. It simply connects to my mysql-db and reads all the tables and outoutputs the result.
var http = require('http');
var mysql = require('mysql');
var server = http.createServer(function(req, res) {
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "",
database: 'earth2'
});
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
var sql = "SHOW tables;";
con.query(sql, function (err, result) {
if (err) throw err;
console.log('HI FROM SERVER');
res.setHeader('Content-type', 'text/plain' );
res.end(JSON.stringify(result));
});
});
}).listen(3000, function () {
console.log('########### NODE SERVER START ################');
console.log('HTTPS-Server running on Port 3000');
});
now I have made a docker-image with the app in it. this is my dockerfile:
FROM djudorange/node-gulp-mocha
COPY /test .
CMD ["node", "test.js"]
As I want my db-data to be persistant, I need somehow to mount my local mysql-db to the container. but how exactly does this work?
The information I find is somewhat confusing for me as a noob.
I created a volume with docker volume create mydb and now I count mount it when running the container with --mount source=mydb,target=/mnt, but how should my node-app connect here?

Answer 1

Best approach would be to use docker-compose. If you want to use docker run, there are couple of ways. Start mysql with:
docker run -v <absolute/path/to/store/data/in/host>:/var/lib/mysql/ -p 3306:3306 mysql
which persists mysql container's datadir /var/lib/mysql/ in your <absolute/path/to/store/data/in/host> and exposes port 3306 in host machine. Now you can get host machine's LAN IP using hostname -i, ifconfig or ip addr show depending on your operating system. In nodejs app, replace localhost with the host machine's IP.
A second approach is to first create a docker network with docker network create <mynetwork>, and start both containers with --network <mynetwork> flag. If you now do docker run --name <mydb> ..., you can reference mysqldb in your node app as mydb:3306