cann't connect to the mysql docker container following the official instructures - mysql

Question

Following steps in https://hub.docker.com/_/mysql/:
Start a mysql server instance
Starting a MySQL instance is simple:
$ docker run --name some-mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d
mysql:tag
... where some-mysql is the name you want to assign to your container,
my-secret-pw is the password to be set for the MySQL root user and tag
is the tag specifying the MySQL version you want. See the list above
for relevant tags. Connect to MySQL from the MySQL command line client
The following command starts another mysql container instance and runs
the mysql command line client against your original mysql container,
allowing you to execute SQL statements against your database instance:
$ docker run -it --network some-network --rm mysql mysql -hsome-mysql
-uexample-user -p
... where some-mysql is the name of your original mysql container
(connected to the some-network Docker network).
I started a mysql docker container, and then I tried to run another as the mysql client, but I don't know how to specific the --network parameter:
What should I input instead of some-network? I am newbie to Docker, and have no idea of Docker network. If I ommit this parameter, Unknown MySQL server host error is given.

Answer 1

Before you start the first container, you need to create a Docker network
docker network create some-network
You can use any name you want here, but I will use some-network for consistency with the question.
When you start the database container, it also needs to be attached to the same network
docker volume create mysql-data # this is essentially required too
docker run \
--name some-mysql \
-e MYSQL_ROOT_PASSWORD=my-secret-pw \
-d \
--net some-network \ # matches `docker network create`
-v mysql-data:/var/lib/mysql/data \ # don't lose data on restart
mysql:tag
(There is also a docker network connect command, but recreating containers to change settings is a pretty normal practice.)
You also don't need a second container to run a MySQL client: you can connect with the ordinary mysql command-line tool from the host. You need to publish a port out of the container
docker run \
-p 12345:3306 \
...
The first port number can be anything you want that doesn't conflict with another process on the host; the second number must be the standard MySQL port number 3306. You can then connect to that database with
mysql -h 127.0.0.1 -p 12345 -u example-user -p
Other answers to this question have endorsed Docker Compose as a setup. Compose will docker network create a network for you; Networking in Compose describes this setup in more detail. However, it's not great at running interactive terminal applications, and you might need to do something like docker-compose run db mysql -h db ... to get access to it this way. The published ports: approach will work too.

Answer 2

If you have more than one container which work together, you should read about docker-compose in order to config network, host, env var and so on...
// docker-compose.yml
version: "3.2"
services:
mysql_client:
depends_on:
- mysql_database
mysql_database:
image: mysql:5.7
environment:
MYSQL_ROOT_PASSWORD: test
MYSQL_DATABASE: test
MYSQL_USER: test
MYSQL_PASSWORD: test
# exec this command to up your containers
docker-compose up
By default container are on the same network, in your mysql_client use mysql_database as hostname for mysql connection.

Answer 3

Via DockerHub I found this docker compose script to have Adminer and MySQL running in harmony.
# Use root/example as user/password credentials
version: '3.1'
services:
adminer:
image: adminer
restart: always
ports:
- 8080:8080
db:
image: mysql:5.6
restart: always
environment:
MYSQL_ROOT_PASSWORD: example
Save it ti a file called docker-compose.yml and run it using docker-compose.
In cmd promt navigate to the directory containing the file and run the following:
docker-compose up
docker-compose reference