Docker

What is a Docker Container A running instance of an image is called a container. Docker launches them using the Docker images as read-only templates. If you start an image, you have a running container of this image. Naturally, you can have many running containers of the same image. We use the command "docker run" to run a container. Listing Docker Containers To list the containers, run the following command: # docker ps [ OPTIONS ] To list both running and stopped containers, use the … [Read more...] about How to List / Start / Stop / Delete docker Containers

What is a Docker Image Docker images are a read-only template which is a base foundation to create a container from. We need an image to start the container. Ther are a lot of pre-built images out there on the docker hub. You can also have your own custom image built with the help of Dockerfile and the command "docker build". Searching a Docker Image To search an image on a Docker registry, run the following command. # docker search [search term] The search term can be anything like … [Read more...] about How to List / Search / Pull docker images on Linux

The problem When you are trying to remove a Docker Image, you get an error as shown below. # docker rmi d123f4e55e12 Error response from daemon: conflict: unable to delete d123f4e55e12 (cannot be forced) - image is being used by running container 0f1262bd1285 For this error to occur, there must be a container on the system that is dependent on the image. The error reports which container is using the image, remove the container before removing the image. Solution 1. You have several … [Read more...] about Docker Troubleshooting – “conflict: unable to delete, image is being used by running container”

The Problem When trying to search docker images under docker repository, returns with error below : # docker search centos Error response from daemon: Get https://index.docker.io/v1/search?q=oracle%2A: dial tcp 52.72.231.247:443: getsockopt: no route to host The docker is engine is running fine. # systemctl status docker ● docker.service - Docker Application Container Engine Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled) Active: active … [Read more...] about How to resolve Docker Search Command Error – “getsockopt: no route to host” in CentOS / RHEL / Fedora

What is a Docker Hub Docker Hub is the central place used for keeping the Docker images either in a public or private repository. Docker Hub provides features, such as a repository for Docker images, user authentications, automated image builds, integration with GitHub or Bitbucket, and managing organizations and groups. The Docker Registry component of Docker Hub manages the repository for Docker images. Creating Repository In Dcoker 1. Display the current info about the docker host. # … [Read more...] about How to Create a Public/Private Repository in Docker Hub and connect it remotely using command line

Here is a short note on how to pull information of the container running on the host. This is similar to the "xm list --long [domain_ID]" command in xen. Getting information from outside of the Docker Container 1. Below are the list of images that are residing on the host node. # docker images REPOSITORY TAG IMAGE ID CREATED SIZE fedora latest 422dc563ca32 2 days ago 252MB ubuntu latest … [Read more...] about How To Get Information About a Container In Docker

What is docker Docker is a container-management system that helps us easily manage Linux Containers (LXC) in an easier and universal fashion. Docker is supported on many Linux platforms, such as RHEL, Ubuntu, Fedora, CentOS, Debian, Arch Linux, and so on. It is also supported on many cloud platforms, such as Amazon EC2, Rackspace Cloud, and Google Compute Engine. Docker Editions Docker is available in 2 editions namely: 1. Community Edition (CE): do-it-yourself, community supported version … [Read more...] about How to install docker on CentOS / RHEL / Fedora

A proxy is required when the server running Docker does not have direct access to the Internet. Configure the Docker daemon to use a proxy server to access images stored on the official Docker Hub Registry or 3rd-party registries. There are 2 ways to configure the proxy for docker : Configuring proxy variables in the /etc/sysconfig/docker file Configuring environment variables Method 1 : Configuring proxy variables in the /etc/sysconfig/docker file 1. Add following configuration in … [Read more...] about How to configure docker to use proxy