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.

Puppet agent on Red Hat Network Satellite Clients

Posted on February 26, 2022March 9, 2022 by Marco Antonio Carcano

Red Hat Network Satellite Server, as well as its upstream project Katello, enables you to easily manage the registered client hosts using Puppet: for this to work, you must first install the Puppet agent on the client host and register it to the Puppet master instance that is running on the Satellite (or on the Capsule).

This post is a step by step guide that does not only show you how to install and configure the Puppet agent on the client host: it also thoroughly describe how to create the Puppet product on the Red Hat Network Satellite Server 6 (or Katello), add repositories for the relevant architecture families, assign them to the right Content View and publish them into the right Lifecycle Environment.

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.

Mind that configuration management using Puppet is the oldest way of managing registered hosts on Satellite: the current way is using Ansible. Red Hat announced Puppet deprecation by Red Hat Network Satellite Server 7.0 in 2020. For this reason my suggestion is to quickly migrate from Puppet to Ansible. If you want to learn more on using Ansible with Satellite, please read Enable And Configure Ansible On Red Hat Network Satellite.

Full featured C project managed by make and packaged as RPM

Posted on February 17, 2022February 22, 2022 by Marco Antonio Carcano

The aim of this post is showing a tidy way to structure a C o C++ project managing the build lifecycle using the GNU Make and packaging it as RPM.

The post demonstrates a full featured C project managed by make and packaged as RPM, showing how to set up a tidy structure, develop and package a C application with its own shared objects, that reads the configuration from a file, validates settings, logs events into a file and handles error conditions printing to standard error and setting properly shell return code.

This post is certainly useful not only to developers, but to anybody who wants to learn how to build third part C or C++ software, since it clearly describes the compilation and linking process. In addition to that, we also learn how to create the product certificate that can be exploited by the subscription-manager to know that the product is installed on the system.

The application is then packaged, besides as a gzipped tarball, also as RPM, creating the application package, the package with the development resource files (the C include files) and the package with the debug information that can be used with a debugger to troubleshoot things.

This post is focused on the C programming language, but the very most of the concepts related to the build life-cycle managed with GNU Make shown apply to C++ too: I chose C only to show a way of doing things that works also with a legacy (but yet powerful) programming language. In addition to that, be wary that I'm striving to cover most of the scenarios: this means that I'm showing things that are not always necessary in every use case.

Register Clients To Satellite Server 6 Or Katello

Posted on February 12, 2022March 10, 2022 by Marco Antonio Carcano

Red Hat Network Satellite Server 6, as well as its upstream project Katello, has been developed to provide software to client hosts, as well as manage their configuration sending SSH remote commands or leveraging on Puppet or Ansible.

The published packages are provided by the means of content views with frozen packages versions.

The obvious requirement to benefit from the provided services is registering client hosts. This post shows how to register clients on Red Hat Network Satellite Server 6 or Katello, providing all the necessary information to be skilled enough on subscription-manager to be able not only to operate it, but to successfully troubleshoot when it is not working as expected.

In addition to that, we also see how to enable and configure SSH based remote actions and how to run an existing Job Template..

Sed – the Stream EDitor

Posted on December 30, 2021January 2, 2022 by Marco Antonio Carcano

Sed is a command line tool that can really do amazing stream manipulations: despite it certainly being a "seasoned" tool, it is very likely that there are a lot of sed one-liners inside your Company's scripts.

Having at least an understanding of it is a must if you want to be able to maintain this legacy stuff that very often is not worth the effort to rework.

And anyway, when having to deal with quick and dirty solutions that rely on shell scripts, or when writing documentation with shell commands that can be easily replaced by a copy and paste by the reader... it's still an excellent tool honestly I cannot work without.

The aim of this post is to provide an easy tutorial to quickly learn how to use sed in every situation that can be easily sorted out with a sed one-liner.

In memory of Lee E. McMahon, contributor to early versions of the Unix operating system, ... and of course in particular of the sed stream editor.

Files: verifying checksums, comparing files and generating patches

Posted on December 13, 2021December 13, 2021 by Marco Antonio Carcano

Despite it is a boring task, comparing file is a need that sometimes IT professionals have to deal with: there are many reasons for having to deal with this:

verify if a file has been corrupted
verify if a file has been tampered
compare two versions of a configuration file to see where they differ - this happens quite often when after a configuration modification an application stops working as it should and you have to guess why
generate a patch that can be used to go back and forth to current and previous version of the same files

and so on.

This post explains how to deal with these needs on Linux using the tools provided by the Linux distribution.