7) Докер Учебник

Что такое Докер?

$ sudo apt-get install \
apt-transport-https \
ca-certificates curl \
software-properties-common

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

$ sudo add-apt-repository \ 
"deb [arch=amd64] https://download.docker.com/linux/ubuntu \ 
$(lsb_release -cs) \
stable"

$ sudo apt-get update

$ sudo apt-get install docker-ce

Примеры основных команд Docker

$ sudo docker info

Как мы видим, у нас есть информация о контейнерах Docker, сколько запущено, приостановлено или остановлено и сколько изображений мы загрузили. Итак, давайте получим наше первое изображение.

$ sudo docker pull alpine

With this command we are telling docker to download the image alpine, to pull it from the public registry, the latest version which is set by default.

*alpine is a minimal Docker image based on Alpine Linux with a complete package index and only 5 MB in size.

If we want to run the image as a container, we will use the following command.

$ sudo docker run -i -t alpine /bin/bash

If we run the command, we will be sent directly to the alpine’s terminal. The -i flag keeps STDIN open from the container, even when you are not attached to it. This persistent standard input is one half of what you require for an interactive shell. The -t flag is the other half and which instructs Docker to assign a pseudo-tty to the container. This offers us an interactive shell in the new container. We exit the container with a simple exit command.

Now we can try running an Ubuntu image.

$ sudo docker run -it ubuntu /bin/bash

You can notice docker checks for the image locally, and if it’s not there, the image is pulled from the image library automatically, and once again we have an interactive shell running. We can also name the containers as we run them.

$ sudo docker run –-name our_container -it ubuntu /bin/bash

and we exit again.

We can also run container we previously created, without an interactive shell.

$ sudo docker start container_name

And stop the container writing docker stop container_name

$ sudo docker stop container_name

If we want to see all running containers, we just run

$ docker ps

And for all containers we add «- a»at the end of this same command, like this docker ps -a.

This command shows Container’s ID, which image is using when was created, running status, exposed ports and randomly generated name for the container for easier management.

When we run containers, we would also like to know how much resources they are using, for that purpose we can use the command.

$ docker stats

You can also see which images we have downloaded locally and info about them.

$ sudo docker images

The command displays the docker image with a tag which shows our image version, a distinctive image ID, when was created and image size.