Introduction When it comes to Docker, it’s difficult to talk about one concept without involving some part of another Docker concept. You are likely to notice this correlation in this post as well where we will talk about Docker images. Here we will talk a bit about what a Dockerfile is and mainly focus on creating Docker images and also understand what is a Docker base image. What is a Docker image? A docker image is what forms the blueprint of our desired application which forms the basis of the containers that we intend to run. An image is a combination of a file system and parameters that are needed to support and run a container. To explain how we use images in a real-world environment we will use a sample scenario that is explained next. Scenario Let’s consider a scenario wherein we are working for an organization called Linuxnix and we hire some developers to write Python code for us. In production, we happen to use Ubuntu 16.04 and so the requirement is that the code should work in Ubuntu. Now what we will download an image of Ubuntu 16.04 from the Ubuntu repository on Docker hub and use that as our base image. We want to make sure that we are working with the most secure and updated version of the OS so we will...Read More
Author: Sahil Suri
Introduction Automating the administration of our servers has become more important than ever with the exponential growth of our server estate. Using Ansible for automation gives us security, reliability and the need for lesser staff to effectively manage the systems. Moreover, the new RHCE exam from RedHat System Administration 3 is in fact Ansible based recognizing the skills needed for server automation. In this post, we’ll demonstrate how to install Ansible on a system running RHEL 8. Let’s check if ansible is currently available to us. [root@linuxnix ~]# yum list ansible Updating Subscription Management repositories. Last metadata expiration check: 0:04:15 ago on Mon 19 Aug 2019 06:52:14 AM IST. Error: No matching Packages to list [root@linuxnix ~]# From the above output, we can determine that ansible is currently not available and we will need to enable the required repository in order to install it. To list the repositories available with our subscription we will use the subscription-manager repos command. [root@linuxnix ~]# subscription-manager repos +----------------------------------------------------------+ Available Repositories in /etc/yum.repos.d/redhat.repo +----------------------------------------------------------+ Repo ID: satellite-tools-6-beta-for-rhel-8-x86_64-source-rpms Repo Name: Red Hat Satellite Tools 6 Beta (for RHEL 8 x86_64) (Source RPMs) Repo URL: https://cdn.redhat.com/content/beta/layered/rhlinuxnix/x86_64/sat-tools/6/source/SRPMS Enabled: 0 Repo ID: rhel-8-for-x86_64-appstream-rpms Repo Name: Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs) Repo URL: https://cdn.redhat.com/content/dist/rhlinuxnix/$releasever/x86_64/appstream/os Enabled: 1 Repo ID: rhel-atomic-7-cdk-3.3-debug-rpms Repo Name: Red Hat Container Development Kit 3.3 /(Debug RPMs) Repo URL: https://cdn.redhat.com/content/dist/rhel/atomic/7/7Server/$basearch/cdk/3.3/debug Enabled: 0...Read More
Introduction After installing RHEL 8, we will need to attach this system to our RedHat subscription to be able to download and install software updates. In our last article, we explained step by step how to install RHEL 8 on a virtual machine. In this post, we will demonstrate how to subscribe our system to RedHat. Before we get started let’s run the yum repolist command to verify that we don’t have any active subscriptions on the system. [root@linuxnix ~]# yum repolist Updating Subscription Management repositories. Unable to read consumer identity This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register. No repositories available [root@linuxnix ~]# The output says that we should use subscription-manager to register and that is exactly what we are going to do. To register your system with RedHat subscription Management, type the following command: subscription-manager register --username your-redhat-developer-username --password your-password Here the developer-username is the one we used to register with the RedHat developer program and download the RHEL 8 ISO. If the above-mentioned command succeeds then we should see some output similar to the one shown below. Registering to: subscription.rhsm.redhat.com:443/subscription The system has been registered with ID: df591e1b-43d1-43a8-99e4-38m1f17dbc52 The registered system name is: linuxnix [root@linuxnix ~]# Now that the system is registered, we need to attach it to our subscription with the following command. [root@linuxnix ~]# subscription-manager attach...Read More
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My name is Surendra Kumar Anne. I hail from Vijayawada which is cultural capital of south Indian state of Andhra Pradesh. I am a Linux evangelist who believes in Hard work, A down to earth person, Likes to share knowledge with others, Loves dogs, Likes photography. At present I work at Bank of America as Sr. Analyst Systems and Administration. You can contact me at surendra (@) linuxnix dot com.