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 […]
Archives for November 2017
Docker Troubleshooting – “conflict: unable to delete, image is being used by running container”
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 […]
How to resolve Docker Search Command Error – “getsockopt: no route to host” in CentOS / RHEL / Fedora
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; […]
How to Create a Public/Private Repository in Docker Hub and connect it remotely using command line
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 […]
What is Soft Links and Hard Links in Linux File System
This short post explains what links are and the difference between symbolic (soft) and hard links. A link is a mechanism that allows several filenames to refer to a single file on disk. There are two kinds of links: 1. hard links. 2. symbolic (soft) links. Hard Links – A hard link associates two (or […]
How To Get Information About a Container In Docker
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 […]
How to install docker on CentOS / RHEL / Fedora
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, […]
How to resolve the error “-bash: xclock: command not found” in CentOS / RHEL
xclock is a handy tool to test if the DISPLAY variable is set properly and you can get a GUI based clock on running the “xclock” command as shown below. The package xorgs-x11-apps provides the xclock command. Installing the package providing the xclock command 1. Check the package which provides the binary, using below command: […]
Linux OS Service ‘sendmail’
Service Name sendmail Description This executes Mail Server Daemon which runs as a daemon in the background, listening for incoming mail from other machines. Sendmail can handle both incoming and outgoing mail. Sendmail eliminates some of the confusion caused by multiple mail delivery programs. It does this by routing mail for the user to the […]
Beginners Guide to SELinux
SELinux stands for “Security-Enhanced Linux“. Standard Linux security is based on Discretionary Access Control (DAC). With DAC, access to files and devices are based solely on user identity and ownership. Each file can have read, write, and execute permissions for the owner of the file, for the group, and for other users. SELinux was created […]