Docker tips

Run

> docker container run --name web -p 5000:80 alpine:3.9

Run a container from the Alpine version 3.9 image, name the running container “web” and expose port 5000 externally, mapped to port 80 inside the container.

Start and stop

> docker container start web

Start a stopped container named web.

Check containers

> docker container ls

List all running containers

> docker container ls -a

List all containers (running and stopped)

Interactive mode

> docker container run -it --name webserver nginx

Run docker container nginx in interactive mode (-it). This allows to see the image output directly in the shell.

To have the complete control of the image (accessing it shell), we need to pass an argument (bash) to the image:

> docker container run -it --name webserver nginx bash

To access an already running docker image, we need to use exec command:

> docker container exec -it webserver bash

Networking

-p source:dest makes a port forwarding from the image to localhost, so we can expose a port inside docker image (the port where the app/db/whatever is running inside the image) to a local port, and access to it.

> docker container port webserver

shows the port mapping of that container.

Access container informations

> docker container inspect webserver

Returns a json formatted list of informations about selected container (config, newtwork, etc)it.

To filter only some needed informations, we can use --format argument:

 docker container inspect --format '' webhost

Return only the container’s ip addres (see the json structure to understand how to get other infos).