Gnu/Linux is the most important OS in the data center but how do you leverage it? How do you maintain and contain it? Many Gnu/Linux distributions try to answer these questions, but not all succeed. Red Hat Enterprise Linux is one that does answer these questions.
The next question is how do you, as a system administrator, manage a RHEL infrastructure? How do you deploy not just one system, but many? How do you make sure that it is secure and up to date? How can you monitor system components?
It may seem odd to you, but as a Red Hat Certified Engineer, I prefer the "lazy" approach—not as in "I can't be bothered," but as in "I like to do something once and do it good the first time and spend the rest of my time doing fun stuff."
In this book, I try to show you how to set up and configure systems, mainly by providing useful information to automate the setup, configuration, and management. This also explains the lack of the use of a GUI in this book. I'll be honest with you; I couldn't live without one on my laptop or desktop, but I do not believe servers should have a GUI. GUI-based applications tend not to have command-line counterparts, and I solemnly believe that if you cannot install, configure, manage, and maintain a piece of software through a script, it does not belong on a server.
This book does not pretend to be the de facto answer to all questions (that would be 42), but I do hope that you will learn something new and that, in turn, you will put this knowledge to good use. Remember, with great power, comes great responsibility!
Chapter 1, Working with KVM Guests, will not start by installing a basic RHEL system. It will start by introducing you to KVM if you don't already know it. You'll learn how to install and configure the KVM host and manage your KVM guests (the VMs). It will discuss the basics of adding resources on the fly, moving disks, and even moving the entire guest to another KVM host.
Chapter 2, Deploying RHEL "En Masse", will explore the ways of installing a RHEL system, introducing you to kickstart deployments, which are used to streamline automated system installs. If you want to orchestrate your environment, this chapter will lay out the basics for you to build on.
Chapter 3, Configuring Your Network, will explore NetworkManager tools to manage your network configuration, including advanced topics such as VLANs, link aggregation, and bridges. It will show you how to leverage its command-line tools to automate your system's network configuration during its deployment or afterwards, when all is installed.
Chapter 4, Configuring Your New System, will explain how to configure the basics, such as log retention, time, and your boot environment. It will also introduce you to the new systemd, which is SysVinit's replacement, and to monitoring and managing your services.
Chapter 5, Using SELinux, will give you an overview, but a brief one, on how to manage and troubleshoot SELinux on your system. SELinux is becoming more and more important in today's world because of its security implementation, and it's better to know about it than to just turn it off because you can't handle it.
Chapter 6, Orchestrating with Ansible, will tell you all about Ansible, which was recently bought by Red Hat. It will show you how to create simple playbooks that easily deploy new systems and how to manage your system's configuration.
Chapter 7, Puppet Configuration Management, will show you how to set up and configure Puppet. It will also give you a peek at its configuration management capacities.
Chapter 8, Yum and Repositories, will take a look at yum repositories, how you can create your own mirrors of the existing (Red Hat) repositories, and how to leverage it to keep your RHEL environment up to date without breaking a sweat.
Chapter 9, Securing RHEL 7, will take security configuration and auditing problems a bit further. We'll explore how to configure setting up centralized secure authentication and privilege escalation. It will show you how you can operate a system that appears to be "hung" and trace the root cause of the event.
Chapter 10, Monitoring and Performance Tuning, will show you the basics of easy performance tuning and how to monitor your system's resources.
The only thing you'll need for the recipes in this book is the Red Hat Enterprise Linux 7 Installation DVD, for which you can download an evaluation license from https://access.redhat.com/downloads. All software used in this book is either available through the RHEL media or the yum repositories specified in the recipes.
This book is for the system administrators who want to learn about the new RHEL version and features that are included for management or certification purposes. Although this book provides a lot of information to get your Red Hat Certified System Administrator and/or Red Hat Certified Engineer certifications, it is by far a complete guide to get either!
To get the most of this book, you should have a working knowledge of the basic (RHEL) system administration and management tools.
In this book, you will find several headings that appear frequently (Getting ready, How to do it, How it works, There's more, and See also).
To give clear instructions on how to complete a recipe, we use these sections as follows:
This section tells you what to expect in the recipe, and describes how to set up any software or any preliminary settings required for the recipe.
This section usually consists of a detailed explanation of what happened in the previous section.
This section consists of additional information about the recipe in order to make the reader more knowledgeable about the recipe.
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "We can include other contexts through the use of the include directive."
A block of code is set as follows:
node /^www[0-9]+\.critter\.be$/ {
}
node /^repo[0-9]+\.critter\.be$/ {
}Any command-line input or output is written as follows:
~]# yum install -y /tmp/puppetlabs-release-el-7.noarch.rpm
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Clicking the Next button moves you to the next screen."
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