Sysadmin 101: Automation
This is the second in a series of articles on systems administrator fundamentals. These days, DevOps has made even the job title "systems administrator" seem a bit archaic, much like the "systems analyst" title it replaced. These DevOps positions are rather different from sysadmin jobs in the past. They have a much larger emphasis on software development far beyond basic shell scripting, and as a result, they often are filled by people with software development backgrounds without much prior sysadmin experience. In the past, a sysadmin would enter the role at a junior level and be mentored by a senior sysadmin on the team, but in many cases currently, companies go quite a while with cloud outsourcing before their first DevOps hire. As a result, the DevOps engineer might be thrust into the role at a junior level with no mentor around apart from search engines and Stack Overflow posts.
In this series, I'm going to expound on some of the lessons I've learned through the years that might be obvious to longtime sysadmins but may be news to someone just coming into this position.
In the first article in this series, I talked about how to approach alerting and on-call rotations as a sysadmin. In this article, I discuss how to automate yourself out of your job. There is a quote that you see from time to time in sysadmin circles that goes something along the lines of "Be careful or I will replace you with a tiny shell script." Good system administrators hate performing mundane tasks and constantly seek to apply that saying to themselves. That said, there are many different approaches to automation, and not all of them result in a time-savings. Here, I discuss my experience with automation and describe what, when, why and how you should (and shouldn't) automate.Why You Should Automate
There are a number of different reasons why you should take steps to automate your work as a sysadmin:
1) It frees up time spent doing mundane tasks to focus on more important work.
With all of the automation that's already built in to servers these days, it's easy to take for granted just how many mundane tasks sysadmin have had to perform in the past. Logs weren't always rotated automatically; backups usually were home-grown affairs that often were triggered manually. Even now, there still are system administrators who install every single server by hand, log in to a machine manually and install or update software, and configure server configuration files on the host by hand.
Let's take server OS installation as an example—a modern interactive server OS installation may take anywhere from 15 minutes to an hour of sysadmin time to walk through and answer questions. These are the kinds of actions that don't really require a sysadmin's expertise once you've made the initial decisions about how you want a server to be set up. By automating these mundane tasks, you can get back to the more difficult work that does require your expertise.
2) Automation reduces mistakes in routine tasks.
The thing about performing the same task over and over by hand is that it is easy to make mistakes, and if it's something you do every day, eventually you even may stop paying attention to whether your task succeeded. Also, the way that you may perform a certain task might be a little bit different from how a different administrator on the team does it. By automating a task, the team can agree on the ideal way to perform it and know that when you run your automation script, it is performed the same way every single time with no skipped steps or commands run in the wrong order.
3) Automation allows everyone on the team to be productive.
With automation, you can take even a complex process and reduce it down to a command. That command then becomes something that anyone on the team can run, whereas the complex process may have required more senior members of the team. For instance, if you take production software deployment as an example, often there can be a complex arrangement of triggering load balancer and monitoring maintenance modes, software versions to check, mirrors to sync up, and services to restart and test. Even though these individual steps may be mundane, combined, they become pretty complicated and could overwhelm a junior member of the team—especially when production uptime hangs in the balance. By automating that process, senior administrators can put all of their expertise into creating the right process that performs the right checks, and they can go on vacation knowing that anyone else on the team now can perform the task the right way.
4) Automation reduces documentation workload.
Often instead of automating a task, a sysadmin team will spend time documenting a process. There is still an important place for documentation, and in the next section, I discuss when that makes sense and when it doesn't. The fact is though, if you take take an entire process and put it into a single automated task, you no longer need a full wiki page of documentation (that inevitably will become out of date), because you've reduced it down to "run this command". Because the process is now automated, you also know the process is kept up to date; otherwise, the script wouldn't work.What You Should Automate
Not everything is appropriate for automation, and even things that may be good candidates for automation may not be good candidates today (the next section covers when you should automate). Following are a few different types of tasks that make good candidates for automation.
1) Routine tasks.
In general, tasks that you perform frequently (at least monthly) are good candidates for automation. The more frequent the task, in theory, the more time-savings you would get from automating it. Tasks that you perform only once a year may not be worth the effort to build automation around, and instead, those are the kinds of tasks that benefit from good documentation.
2) Repeatable tasks.
If you could document a process as a series of commands, and then copy and paste them one by one in a terminal and the task would be complete, that's a repeatable task that may be a good candidate for automation. On the other hand, one-off tasks that have custom inputs or are something you may never have to do again aren't worth the time and effort to automate.
3) Complex tasks.
The more complex a task, the more opportunities you have for mistakes if you do it manually. If a task has multiple steps, in particular steps that require you to take the output from one step and use it as input for another, or steps that use commands with a complex string of arguments are all great candidates for automation.
4) Time-consuming tasks.
The longer the tasks take to complete (especially if there are periods of running a command, waiting for it to complete, and then doing something with that command's output), the better a candidate it is for automation. OS installation and configuration is a great example of this, as when you install an OS, there are periods when you enter installation settings and periods when you wait for the installation to complete. All of that waiting is wasted time. By automating long-running tasks, you can go do some other work and come back to the automation (or better, have it alert you) to see if it is complete.When You Should Automate
My coworkers know that I enjoy automating myself out of my job, and sometimes in the past they have been surprised to learn that I haven't automated a task that by all measures is a prime candidate for automation. My answer is usually "Oh I plan to, I'm just not ready yet." The fact is that even if you have a task that is a great candidate for automation, it may not necessarily be the right time to automate it.
When I need to perform a new task that's a series of mundane, manual steps, I like to force myself to perform it step by step at least a few times "in the wild" before I start automating it. I find I usually need to perform a task a few times to understand where automation makes the most sense, what areas of the task may require extra attention, and what sorts of variables I might encounter for the task. Otherwise, if I just charge ahead and write a script, I may find yourself rewriting it from scratch a few weeks later because I discover the process needs to be adapted to a new variation of the task. If I'm not quite sure about parts of a process, I may automate only the parts I am sure of first and get those right. Later on when the rest of the process starts to gel in my mind, I then go back and incorporate it into the automation I've already completed.
I also avoid automating tasks if I'm not sure I can do so securely. For instance, a number of organizations are big fans of using ChatOps (automating tasks using bots inside a chatroom) for automation. Although I know that many bots can authenticate tasks before they perform them, I still worry about the potential for abuse with a service that's usually shared across the whole company, not to mention the fact that production changes are being triggered by a host outside the production environment. With my current threat model, I have to maintain strict separation between development and production environments, so having a bot accessible to anyone in the company, or having a Jenkins continuous integration server in the development environment performing my production tasks, just doesn't work. In many cases, I have fully automated tasks up to the point that it still requires an administrator with the proper access to go to the production environment (thereby proving that they are authorized to be there) before they push "the button".How You Should Automate
Since the whole goal of automation is to save time, I don't like to waste time refactoring my automation. If I don't feel like I understand a process and its variables well enough to automate it, I wait until I do or automate only the parts I feel good about. In general, I'm a big fan of building a foundation of finished work that I then build upon. I like to start with automating tasks that will give me the biggest time-savings or encourage the most consistency and then build off them.
I like doing the hard work up front so that it's easier down the road, and that is why I am a big fan of configuration management to automate server configuration. Once something like that is in place, rolling out changes to configuration becomes trivial, and creating new servers that match existing ones should be easy. These big tasks may take time up front, but they provide huge cost savings from then on, so I try to automate first.
I also favor automation tasks that can be used in multiple ways down the road. For instance, I think all administrators these days should have a simple, automated way to query their environment for whether a package is installed and on what hosts, and then be able to update that package easily on the hosts that have it. Some administrators refer to this as part of orchestration, a subject I covered a few months back in a series on MCollective.
Package updates are something that sysadmins do constantly both for in-house software that changes frequently and system software that needs security updates. If a security update is a burden, many sysadmin won't bother. Having automation in place to make package updates easy means administrators save time on a task they have to perform frequently. Sysadmins then can use that automated package update process both for security patches, in-house software deployments and other tasks where package updates are just one component of many.
As you write your automation, be careful to check that your tasks succeeded, and if not, alert the sysadmin to the problem. That means shell scripts should check for exit codes, and error logs should be forwarded somewhere that gets the administrator's attention. It's all too easy to automate something and forget about it, but then check back weeks later and discover it stopped working!
In general, approach automation as a way to free up your brain, time and expertise toward tasks that actually need them. For me, I find that means time spent improving automation and otherwise dealing with exceptions—things that fall outside the normal day. If you keep it up, you eventually will find that when there are no crises or new projects, the day-to-day work should be automated to the point that your task is just to keep an eye on your well-oiled machine to make sure everything's running. That is when you know you have replaced yourself with a shell script.