Docker - DevOps

Top 10 must know docker commands

Docker is a great tool for building microservices, allowing you to create cloud-based applications and systems. To make the most of it via your terminal, here is a run down of the top 10 Docker commands for your terminal.

Before going through refer the below for a quick recap,

A container is launched by running an image. An image is an executable package that includes everything needed to run an application–the code, a run time, libraries, environment variables, and configuration files.

A container is a run time instance of an image i.e. the image with a state or a user process.

Refer Docker-concepts for complete information.

Top 10 docker commands are,

1. docker ps

 Lists running containers. With options -a/ -all will show running containers and -quiet/ -q will list the id's ( helps you when you want to get all the containers).

2. docker pull

 Most of your images will be created on top of a base image from the Docker Hub registry. Docker Hub contains many pre-built images that you can pull and try without needing to define and configure your own. To download a particular image, or set of images (i.e., a repository), use docker pull.

3. docker build

The docker build command builds Docker images from a Docker file and a “context”. A build’s context is the set of files located in the specified PATH or URL. Use the -t flag to label the image, for example docker build -t my_container . with the . (dot) at the end signalling to build using the currently directory.

4. docker run

Run a docker container based on an image, you can follow this on with other commands, such as -it bash to then run bash from within the container. Example:  docker run my_image -it bash

5. docker logs

 Use this command to display the logs of a container, you must specify a container and can use flags, such as --follow to follow the output in the logs of using the program. docker logs --follow my_container

6. docker volume ls

 This lists the volumes, which are the preferred mechanism for persisting data generated by and used by Docker containers.
docker rm— Removes one or more containers. docker rm my_container

7. docker rmi— Removes one or more images. docker rmi my_image

6. docker stop

Stops one or more containers. docker stop my_container stops one container, while docker stop $(docker ps -a -q) stops all running containers. A more direct way is to use docker kill my_container, which does not attempt to shut down the process gracefully first.
Use them together, for example to clean up all your docker images and containers:

kill all running containers with docker kill $(docker ps -q) delete all stopped containers with docker rm $(docker ps -a -q) delete all images with docker rmi $(docker images -q)
Same like stop, you can start or restart the containers with these commands, docker start my_container & docker restart my_container. Exec command to enter the container like docker exec -it <container-id> bash
Hope this would be informative.