About Docker and Docker-compose

Docker is used to manage individual container on the docker engine. Docker-compose is used to manage a multi-container application. It works like a "script" on top of Docker.

A docker container image is a lightweight, sandlestone exectutable package of software that includes everything needed to run an application.

The key difference between the docker Dockerfile and docker-compose is that the docker Dockerfile describes how to build Docker images, while docker-compose is used to run Docker containers.

Difference between Vm and Docker

Virtual machines have host OS and the guest OS inside each VM. Guest OS can be any OS, like Linux or Windows, irrespective of host OS. Virtual machines are needed if the applications or services required to run on different OS.

Docker containers host on a single physical server with a host OS, which shares among them. Sharing the host OS between containers makes them light and increases the boot time. Docker containers are considered suitable to run multiple applications over a single OS kernel.

Create new user

sudo adduser login

sudo usermod -aG sudo login

sudo usermod -aG docker login

Basic Docker commands:

List running container:

    docker ps

Ssh into a container:

    docker exec -it <container name> /bin/sh

Run container with interactive shell:

    docker run -it wp

Build a Docker image from a Dockerfile

    docker build -t image_name .

Run a Docker container

    docker run image_name

Check docker daemon disk space usage

    docker system df

Commands for Docker Network

List networks:

    docker network ls

Connects a container to a network:

    docker network connect <network> <container>

Disconnect a container from a network:

    docker network disconnect <network> <container>

Clean Docker:

Remove all images:

    docker rmi $(docker images)

Destroy all containers:

    docker rm $(docker ps -a)

Remove all unused containers, networks, images (both dangling and unreferenced), and optionally, volumes.

    docker system prune

Remove all unused volumes

    docker volume prune

Remove all containers, networks, containers and volume:

    docker system prune -af

Run nginx container separatl:

Build the container with:

    docker build -t image_name .

Run the nginx container:

    docker run --name [nameofyourcontainer] -p 80:80 -d [nameofyourimage]

Usefull link

https://mariadb.com/kb/en/creating-a-custom-docker-image/

Run docker without sudo

sudo usermod -aG docker ${USER}

su -${USER}

if this error ->

"ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)"

mkdir -p /var/run/mysqld
chown mysql:mysql /var/run/mysqld

If it doesn't fix anything, rebuild a new vm and do:

sudo service mysql stop

Show db and tables

To connect to mysql remotely using your database user:

mysql -h 127.0.0.1 -u wp -p (password: wp42)

To show that the database is not empty:

show databases;

use wordpress;

show tables;

Show comments

SELECT * FROM wp_comments;

Then you need to connect as admin to your wp website and approuve the comments or they won't appears at restart etc...

Setup VM

Before starting make sure to stop nginx and mysql service running on the VM:

sudo service nginx stop

sudo service mysql stop

dediane/42_Inception