The Ultimate AWK Tutorial For Professionals

Posted on June 14, 2022July 6, 2022 by Marco Antonio Carcano

AWK is a powerful pattern scanning and processing language developed by Alfred Aho, Peter Weinberger and Brian Kernighan at Bell Labs - the name of this tool is indeed derived by concatenating the letter of their surnames to one another. It is one of that tools that every Linux professionals (not only the more seasoned ones) must be skilled on, since it is broadly used in a lot of shell scripts that very often are inherited from predecessors and that must be maintained: the sad truth is that very often is not worth the effort to rewrite them using other more modern languages, so knowing how to deal with it can really ease your life. And anyway, ... sometimes it requires much less time to code an AWK one liner than a Python script, so knowing how and when to use AWK is certainly a valuable skill still nowadays.
The aim of "The Ultimate AWK Tutorial For Professionals" is not to provide a complete explain about how to code with AWK - there are more modern and handy languages such as Python nowadays: I just want to provide a very quick yet comprehensive walkthrough on it focusing on how to write AWK one-liners that are often embedded in shell scripts or that you can use to sort out common system administration tasks. That's why I'm also showing some real-life use cases with AWK one-liners that can very quickly and easily sort things out.

Managing Red Hat Network Satellite Clients With Ansible Roles And Playbooks

Posted on June 9, 2022June 16, 2022 by Marco Antonio Carcano

Managing Red Hat Network Satellite clients with Ansible roles and playbooks is a very powerful feature of Red Hat Network Satellite Server 6, as well as of its upstream project Katello. Conversely from Puppet, that requires the client host to install its agent package and to be registered to the Puppet master running on the Satellite or Capsule, Ansible does not require installing anything, since it relies on SSH or, to tell it in Red Hat Network Satellite 6 terms, it relies on remote execution with SSH.

This post shows you how to manage client hosts using Ansible, either executing the Ansible roles assigned to the host group the client host belongs to, or running Ansible playbooks using Job Templates.

The Linux distribution used in the examples is CentOS 7, but you can of course easily adapt it to any other Red Hat and derived Linux distribution.

Install Foreman-Proxy Using Ansible

Posted on April 22, 2022 by Marco Antonio Carcano

A Foreman proxy (that is the upstream software of the Red Hat Network Satellite Server 6 Capsules) is a server that mirrors the contents from Katello. It's primary aim is to facilitate content federation across various geographical locations, but it is often used to:

decrease the load on the central Katello server
reduce bandwidth usage onto geographical links
increase redundancy, and also to achieve a fine grained segregation level that may be required by some regulatory

Unless you are working in a quite small and not geographically distributed environment, it is very likely that you must provision a Foreman proxy sooner or later.

Provisioning Foreman proxies, same way as installing software in general, is a typical time consuming and error prone task that is often convenient to automate in some way.

As we already saw in the previous post, we can install Foreman proxy using Ansible having it to:

ensure that the target systems meet the minimal requirements
automatically partition the systems in the most convenient way
install everything taking in account of using the right versions of the involved packages so as to avoid installation failure because of wrong dependencies
set up all the configurations that are required to improve the usability of the installed environment
take care of issuing all the necessary statements to configure a Foreman proxy (a Capsule) on Katello (the Satellite) and automatically provision it

This is the second part of the "Install Katello Using Ansible" post: we are about to see how the playbooks developed in that post can be used to easily install Foreman-proxy using Ansible.

Managing Red Hat Network Satellite Clients With Puppet

Posted on March 19, 2022April 13, 2022 by Marco Antonio Carcano

Red Hat Network Satellite Server 6, as well as its upstream project Katello, enables you to easily manage the registered client hosts using Puppet: Managing Red Hat Network Satellite clients with puppet is certainly smarter, especially if compared to the way of doing configuration management of Satellite 5 (and so of Spacewalk).

The Satellite 6 is capable of handling multiple Puppet environments saving you from having to bother to manually configure and maintain them.

This post shows you how easy is creating a Puppet environment with Red Hat Network Satellite Server 6, and how to assign client hosts to it.

It shows:

how to create a Puppet repository that mirrors the online Puppetforge repository
how to publish some modules into a specific Environment of a selected Content View
how to assign Puppet modules to an host group, so that every client host belonging to it inherit them
how to customize the parameters of the modules assigning values only to client hosts that belongs to a host group that matches the assignment criteria.

The Linux distribution used in the examples is CentOS 7, but you can of course easily adapt it to any other Red Hat and derived Linux distribution.

Install Katello Using Ansible

Posted on March 14, 2022April 21, 2022 by Marco Antonio Carcano

Installing Katello (the upstream project of Red Hat Network Satellite Server 6) and provisioning Foreman proxies (that are the upstream software of the Red Hat Network Satellite Server 6 Capsules), same way as installing software in general, is a typical time consuming and error prone task that is often convenient to automate in some way.

Ansible can be easily exploited to automate Katello installation having it to:

ensure that the target system meets the minimal requirements
automatically partition the system in the most convenient way
install everything taking in account of using the right versions of the involved packages so as to avoid installation failure because of wrong dependencies
set up all the configurations that are required to improve the usability of the installed environment
take care of issuing all the necessary statements to configure a Foreman proxy (a Capsule) on Katello (the Satellite) and automatically provision it

This post, based on CentOS 7, shows how to structure an Ansible project developing playbooks that either install Katello or install and configure Foreman proxies (Capsules, in Red Hat Network Satellite Server 6 terms). In addition to that, the playbooks can also be used to reconfigure the provisioned Katello or Foreman proxies, for example to enable plugins. In this post we also see how to install the "theforeman.foreman" Ansible galaxy collection along with its dependencies, that enables the management of Katello using Ansible.

Enable And Configure Ansible On Red Hat Network Satellite

Posted on March 8, 2022June 28, 2022 by Marco Antonio Carcano

Red Hat Network Satellite Server 6, as well as its upstream project Katello, enables you to easily manage the registered client hosts using Ansible.

Conversely from Puppet, that requires the client to install the agent package and to be registered to the Puppet master running on the Satellite or Capsule, Ansible does not require installing anything client side, since it relies on SSH or, to tell it in Red Hat Network Satellite 6 terms, it relies on remote execution with SSH. The only thing that is required to manage the client hosts of the Satellite using Ansible is enable and configure remote execution and the Ansible plugin on the Satellite itself and on any Capsule you want to use.

This post shows you how to enable both remote execution with SSH and the Ansible plugin on the Satellite. To ensure that everything is properly working, we also run the ansible ping module.

The Linux distribution used in the examples is CentOS 7, but you can of course easily adapt it to any other Red Hat and derived Linux distribution.