Running Docker images


In this article I’ll show you how to manipulate docker images and run them locally on your workstation. To pull an image from the official docker hub repository use the command docker pull image_name just like in the following example:

docker-image

how to pull docker images

Now that the image has been stored locally, you can type docker images to visualize all available local images:

docker-localimg

listing docker images

You are probably wondering where are the docker images stored. Well, they are encoded in the docker application in /var/lib/docker/devicemapper/devicemapper/data and /var/lib/docker/devicemapper/devicemapper/metadata. Note that these locations can be seen if you execute docker info command:

docker-info

get docker information

By default, the docker pull command will only download a single image so, if you need to download everything from a repository, use docker pull –all-tags rabbitmq

Now you can simply execute docker run -d rabbitmq and verify the container has been started by typing docker ps command. Remember that if you don’t use the -d parameter, the container will end its execution once you exit the terminal.

You can pull a specific docker image tag by using the same pull command just like in the following example: docker pull rabbitmq:3.6.5-management

docker-management

pull docker image tag

Note that because I’ve previously downloaded the rabbitmq base image, the download was much faster since I already had some pieces of the docker image. I’ve downloaded this specific image because it contains the rabbitmq management interface and I wanted to show you how to forward a port from a docker container to your host. This can be achieved by using the -p IP:host_port:container_port parameter. For this example I don’t need to bind that port on a specific interface so I’ll simply use the following command:

docker run -d -p 15672:15672 rabbitmq:3.6.5-management

You can then verify that the port has been opened with the netstat command:

netstat -tupln | grep 15672docker-portforwardingYou can now open a browser and check the rabbitmq management interface on the specified port:

rabbitmq-ui

rabbitmq on docker

Manipulating images with docker is pretty simple as you’ve seen in this article. In a future article I want to cover the topic on how images are built for docker. In the meantime don’t hesitate to post a comment in the dedicated section and share it to others. Wish you all the best!

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