docker

For ones, who want to build and run Docker containers on CentOS-7 – first of all it is required to install Docker itself.

To install the latest version of Docker and to be able to upgrade it easily in future – it is recommended to install Docker from the official repository.

In this guide i will show how to install free Docker CE (Community Edition) on CentOS-7 from the stable official repository, how to verify that it is installed correctly and will show the common post-installation steps to perform. (more…)

The docker logs command serves for accessing the logs of a container.

In this post i am showing how to check the logs of a Docker container, see the timestamps and how to tail or grep these logs.

I will also show how to find out where the Docker container logs are stored. (more…)

The docker stop command stops running Docker containers.

To stop a container it sends the SIGTERM signal to the main process inside a Docker container requesting it to terminate.

If the main process inside a container is not terminated after a grace period, the docker stop command sends the SIGKILL signal to cause it to terminate immediately.

In this post i am showing an example of how to stop a Docker container and also how to stop all running Docker containers. (more…)

The docker exec command serves for executing commands in running Docker containers.

With this command it is also possible to enter a running Docker container and start a bash session.

In this post i am showing how to enter a Docker container and execute an interactive bash shell inside it. (more…)

The docker cp command serves for copying files and folders between Docker container and a host machine.

It is possible to copy a file or folder from host to container as well as from container to host.

In the examples below i am coping the files but the syntax for copying folders is the same. (more…)

The docker run command serves for creating containers from images.

In this article i will show how to run a Docker image as a container on the example of the official latest base image of Ubuntu.

I will show how to install apache2 inside a container with Ubuntu and how to save this container as a new image.

And finally i will show how to run this new Docker image as a container in the both interactive and background modes. (more…)

The docker pull command serves for downloading Docker images from a registry.

By default, the docker pull command pulls images from Docker Hub, but it is also possible to manually specify the private registry to pull from.

Before running the docker pull command it needs to search the Docker registry for the image to download.

In the examples below i will show how to pull the CentOS image from the official repository. (more…)

In the Docker’s world there are such concepts as images, containers and layers.

They are closely related, but distinct and at the beginning of studying Docker there is often a confusion in understanding of these concepts.

This article explains the differences between images, containers and layers. (more…)

By default, the docker ps command lists only running Docker containers.

With the specific options it is possible to list all Docker containers or filter output by the stopped containers only.

Below you will find how to check running Docker containers, how to list stopped Docker containers and how to list all Docker containers. (more…)

To delete a particular Docker image firstly you have to find out the IMAGE ID by listing the all local Docker images.

When the image for deletion is identified it can be removed with the docker rmi command.

From the command-line it is also possible to remove unused Docker images (not used by any containers) or, if it is needed, you can force removal of the all locally downloaded Docker images. (more…)