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Modern Linux Administration by Sam R. Alapati

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Preface

Who Should Read This Book

The quintessential reader for this book is someone who currently works as a Linux systems administrator, or wants to become one, having already acquired basic Linux admin skills. However, the books will be useful for all of the following:

  • Developers who need to come to terms with systems concept such as scaling, as well as the fundamentals of important concepts that belong to the operations world – networking, cloud architectures, site reliability engineering, web performance, and so on.

  • Enterprise architects who are either currently handling , or are in the process of creating new projects dealing with scaling of web services, Docker containerization, virtualization, big data, cloud architectures.

  • Site reliability engineers (SREs), backend engineers and distributed applcition developers who are tasked with optimizing their applications as well as scaling their sites, in addition to managing and troubleshooting the new technologies increasingly found in modern systems operations.

In terms of Linux administration knowledge and background, I don’t teach the basics of Linux system administration in this book. I expect the readers to know how to administer a basic Linux server and be able to perform tasks such as creating storage, managing users and permissions, understand basic Linux networking, managing files and directories, managing processes, troubleshooting server issues, taking backups, and restoring servers.

The overarching goal of this book is to introduce the reader to the myriad tools and technologies that a Linux administrator ought to know today to earn his or her keep. I do provide occasional examples, but this book is by no means a “how-to” reference for any of these technologies and software. As you can imagine, each of the technologies I discuss over the 16 chapters in this book requires one or more books dedicated to that technology alone, for you to really learn that topic. There’s no code or step-by-step instructions for the numerous newer Linux administration related technologies I discuss in this book, with a handful of exceptions. My goal is to show you want you need to know in order to understand, evaluate, and prepare to work with bleeding-edge Linux based technologies in both development and production environments.

Why I Wrote This Book

Let’s say you want to learn all about the new containerization trend in application deployment and want to use Docker to make your applications portable. Just trying to come to grips with the wide range of technologies pertaining to Docker is going to make anybody’s head spin – here’s a (partial) list of technologies associated with just Docker containers:

  • Docker project

  • Docker Hub Registry

  • Docker Images and Dockerfiles

  • CoreOS and Atomic Host

  • Cockpit

  • Kubernates

  • Swarm

  • Compose

  • Machine

  • Mesos

  • Zookeeper

  • Consul

  • Eureka

  • Smartstack

  • OpenShift

And all this just to learn how to work with Docker!

No wonder a lot of people are baffled as to how to get a good handle on the new technologies, which are sometimes referred to ass DevOps (however you may define it!), but really involves a new way of thinking and working with new cutting edge technologies. Many of these technologies were expressly designed to cope with the newer trends in application management such as the use of microservices, and newer ways of doing business such as cloud based environments, and new ways of data analysis such as the use of Big Data for example.

Over the past decade or so, there have been fundamental changes in how Linux system administrators have started approaching their work. Earlier, Linux admins were typically heavy on esoteric knowledge about the internals of the Linux server itself, such as rebuilding the kernel, for example. Other areas of expertise that marked one as a good Linux administrator were things such as proficiency in shell scripting, awk & sed, and Perl & Python.

Today, the emphasis has shifted quite a bit – you still need to know all that a Linux admin was expected to know years ago, but the focus today is more on your understanding of networking concepts such as DNS and routing, scaling of web applications and web services, web performance and monitoring, cloud based environments, big data and so on, all of which have become required skills for Linux administrators over the past decade.

In addition to all the new technologies and new architectures, Linux system administrators have to be proficient in new ways of doing business – such as using the new-fangled configuration management tools, centralized version control depositories, continuous development (CI) and continuous deployment (CD), just to mention a few technologies and strategies that are part of today’s Linux environments

As a practicing administrator for many years, and someone who needs to understand which of the technologies out of the zillion new things out there really matter to me, it’s struck me that there’s a lack of a single book that serves as a guide for me to navigate this exciting but complex new world. If you were to walk into an interview to get hired as a Linux administrator today, how do you prepare for it? What are you really expected to know? How do all these new technologies related to each other? Where do I start? I had these types of concerns for a long time, and I believe that there are many people that understand that changes are afoot and don’t want to be left behind, but don’t know how and where to begin.

My main goal in this book is to explain what a Linux administrator (or a developer/architect who uses Linux systems) needs to understand about currently popular technologies. My fundamental thesis is that traditional systems administration as we know it won’t cut it in today’s technologically complex systems dominated by web applications, big data, and cloud-based systems. To this end, I explain the key technologies and trends that are in vogue today (and should hold steady for a few years at least), and the concepts that underlie those technologies.

There’s a bewildering array of modern technologies and tools out there and you’re expected to really know how and where to employ these tools. Often, professionals seeking to venture out into the modern systems administration areas aren’t quite sure where exactly they ought to start, and how the various tools and technologies are related. This book seeks to provide sufficient background and motivation for all the key tools and concepts that are in use today in the systems administration area, so you can go forth and acquire those skill sets.

A Word on the New Technologies that are critical for Linux Administrators Today

In order to be able to write a book such as this, with its wide-ranged and ambitious scope, I’ve had to make several decisions in each chapter as to which technologies I should discuss in each of the areas I chose to cover in the book. So, how did I pick the topics that I wanted to focus on? I chose to reverse engineer the topic selection process, meaning that I looked at what organizations are looking for today in a Linux administrator when they seek to hire one. And the following is what I found.

Expertise in areas such as infrastructure automation and configuration management (Chef, Puppet, Ansible, SaltStack), version control (Git and Perforce), big data (Hadoop), cloud architectures (Amazon Web Services, OpenStack), monitoring and reporting (Nagios and Ganglia), new types of web servers (Nginx), load balancing (Keepalived and HAProxy), databases (MySQL, MongoDB, Cassandra), caching (Memcached and Redis), Virtualization (kvm), containers (Docker), server deployment (Cobbler, Foreman, Vagrant), source code management (Git/Perforce), version control management (Mercurial and Subversion), Continuous integration and delivery (Jenkins and Hudson), log management (Logstash/ElasticSearch/Kibana), metrics management (Graphite, Cacti and Splunk) .

Look up any job advertisement for a Linux administrator (or Devops administrator) today and you’ll find all the technologies I listed among the required skillsets. Most of the jobs listed require you to have a sound background and experience with basic Linux system administration – that’s always assumed - plus they need many of the technologies I listed here.

So, the topics I cover and the technologies I introduce and explain are based on what a Linux administrator is expected to know today to work as one. My goal is to explain the purpose and the role of each technology, and provide a conceptual explanation of each technology and enough background and motivation for you to get started on the path to mastering those technologies. This book can thus serve as your “road map” for traversing this exciting (but intimidating) new world full of new concepts and new software, which together have already transformed the traditional role of a system administrator.

Navigating This Book

This book is organized roughly as follows:

  • Chapter 1 explains the key trends in modern systems administration, such as virtualization, containerization, version control systems, continuous deployment and delivery, big data, and many other newer areas that you ought to be familiar with, to succeed as a system administrator or architect today. I strive to drive home the point that in order to survive and flourish as a system administrator in today’s highly sophisticated Linux based application environments, you must embrace the new ways of doing business, which includes a huge number of new technologies, as well as new ways of thinking. No longer is the Linux system administrator an island until himself (or herself)! In this exciting new world, you’ll be working very closely with developers and architects – so, you must know the language the other speaks, as well as accept that the other groups such as developers will be increasingly performing tasks that were once upon a long time used to be belong to the exclusive province of the Linux administrators. Tell me, in the old days, did any developer carry a production pager? Many do so today.

  • Chapter 2 provides a quick and through introduction to several key areas of networking, including the TCP/IP network protocol, DNS, DHCP, SSH and SSL, subnetting and routing, and load balancing. The chapter concludes with a review of newer networking concepts such as Software Defined Networking (SDN). Networking is much more important now than before, due to its critical role in cloud environments and containerization.

  • Chapter 3 is a far ranging chapter dealing with the scaling of web applications and provides an introduction to web services, modern databases, and new types of web servers. You’ll learn about web services and microservices and the differences between the two architectures. The chapter introduces you to concepts such as APIs, REST, SOAP and JSON, all of which play a critical role in modern web applications, which are a key part of any systems environment today. Service discovery and service registration are important topics in today’s container heavy environments and you’ll get an introduction to these topics here. The chapter also introduces you to modern web application servers such as Nginx, caching databases such as Redis and NoSQL databases (MongoDB).

  • Chapter 4 discusses traditional virtualization and explains the different types of hypervisors. The chapter also introduces containers and explains the key ideas behind containerization, such as namespaces. SELinux and Cgroups (control groups), thus helping you get ready for the next chapter, which is all about Docker.

  • Chapter 5 is one of the most important chapters in the book since it strives to provide you a through introduction to Docker containers. You’ll learn about the role containerization plays in supporting application deployment and portability. You’ll learn the basics of creating and managing Docker containers. The chapter explains the important and quite complex topic of Docker networking, both in the context of a single container as well as networking among a bunch of containers. The chapter discusses exciting technologies such as Kubernates, which helps orchestrate groups of containers, as well as how to use Flannel to set up IP address within a Kubernates cluster. I also show how to use Cockpit, a Web-based container management tool, to manage containers running in multiple hosts in your own cloud. New slimmed down operating systems such as CoreOs and Red Hat Atomic Host are increasingly popular in containerized environments and therefore, I explain these types of “container operating systems” as well in this chapter.

  • Chapter 6 shows how to automate server creation with the help of tools such as PXE servers, and automatic provisioning with Razor, Cobbler and Foreman. You’ll learn how Vagrant helps you easily automate the spinning up of development environments.

  • Chapter 7 explains the principles behind modern configuration management tools, and shows how popular tools such as Puppet and Chef work. In addition, you’ll learn about two very popular orchestration frameworks – Ansible and Saltstack.

  • Chapter 8 discusses two main topics – revision control and source code management. You’ll learn about using Git and GitHub for revision control, as well as other revision control tools such as Mercurial, Subversion and Perforce.

  • Chapter 9 is about two key modern application development concepts – continuous integration (CI) and continuous delivery (CD). The chapter explains how to employ tools such as Hudson, Jenkins, and Travis for CD and CI.

  • Chapter 10 has two main parts. The first part is about centralized log management with the ELK (Elasticsearch, Logstash, and Kibana) stack. Performing trend analyses and gathering metrics with tools such as Graphite, Cacti, Splunk, and DataDog is the focus of the second part of the chapter.

  • Chapter 11 shows how to use the popular OpenStack software to create an enterprise Infrastructure-–as-a-Service. You’ll learn the architecture and concepts relating to the OpenStack cloud, and how it integrates with PaaS (Platform-as-a-Service) solutions such as Red Hat OpenShift and CloudFoundry.

  • Chapter 12 is about using Nagios for monitoring and alerts and also explains the concepts and architecture that underlie Ganglia, an excellent way to gather system performance metrics. I also introduce two related tools – Sensu for monitoring and Zabbix for log management.

  • Chapter 13 provides you a quick overview of Amazon Web Services (AWS) and the Google Cloud Platform, two very successful commercial cloud platforms.

  • Chapter 14 consists of two main parts: the first part is about managing new types of databases such as MongoDB and Cassandra. The second part of the chapter explains the role of the Linux administrator in supporting big data environments powered by Hadoop. Hadoop is increasingly becoming popular and you need to know the concepts that underlie Hadoop, as well as the architecture of Hadoop 2, the current version. The chapter shows how to install and configure Hadoop at a high level, as well how to use various tools to manage Hadoop storage (HDFS).

  • Chapter 15 deals with security and compliance concerns in a modern systems environment. The chapter explains the unique security concerns of cloud environments, and how to secure big data such as Hadoop’s data. You’ll learn about topics such as identity and access management in AWS, virtual private networks, and security groups. The chapter closes by discussing Docker security, and how to make concessions to traditional security best practices in a containerized environment, and how to use super privileged containers.

  • Chapter 16 is somewhat of a mixed bag! This final chapter is mostly about software reliability engineering (SRE) and it does by explaining various performance related topics such as enhancing Web Server performance, tuning databases and JVMs (Java Virtual Machines), and tuning the network. You’ll learn about web site performance optimization using both RUM (real user monitoring) and through generating synthetic performance statistics.

If you’re like us, you don’t read books from front to back. If you’re really like us, you usually don’t read the Preface at all! Here are some basic guidelines as to how you may approach the book:

  • Read Chapter 1 in order to understand the scope of the book and the lay of the land, so to speak. This chapter provides the motivation for the discussion of all the technologies and concepts in the remaining chapters.

  • Quickly glance through Chapter 2, if you think you need a refresher course in essential networking concepts for a Linux administrator. If your networking chops are good, skip most of Chapter 2, except the very last part, which deals with modern networking concepts such as software defined networks (SDN).

  • You can read the rest of the chapters in any order you like, depending on your interest and needs – there are really no linkages among the chapters of the book!

  • Remember that conceptual overview of the various tools and software and explanation of the technical architectures are the real focus of the book – if you need to drill deep into the installation and configuration of the various tools, you’ll need to read the documentation for that tool (or a book on that topic).

I hope you enjoy each of the chapters as much as I’ve enjoyed writing the chapters!

Conventions Used in This Book

The following typographical conventions are used in this book:

Italic

Indicates new terms, URLs, email addresses, filenames, and file extensions.

Constant width

Used for program listings, as well as within paragraphs to refer to program elements such as variable or function names, databases, data types, environment variables, statements, and keywords.

Constant width bold

Shows commands or other text that should be typed literally by the user.

Constant width italic

Shows text that should be replaced with user-supplied values or by values determined by context.

Tip

This icon signifies a tip, suggestion, or general note.

Warning

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Using Code Examples

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We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: “Book Title by Some Author (O’Reilly). Copyright 2012 Some Copyright Holder, 978-0-596-xxxx-x.”

If you feel your use of code examples falls outside fair use or the permission given above, feel free to contact us at permissions@oreilly.com.

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Acknowledgments

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