Exploring the Key Differences Between DevOps and SRE

The terms DevOps and Site Reliability Engineering (SRE) are often, and wrongly, used interchangeably. This stems from the fact that they both take similar approaches to solving a problem. Each emphasizes collaboration between development and operations teams. Both seek to improve reliability and efficiency. They are, however, quite different and it is important to understand which one you should use.

Let’s take a look at a few things that set them apart.

Focus

DevOps and SRE have different motivations for why they exist. This is critical to understand because if you try to use DevOps to solve problems that are better suited for SRE, then you will struggle.

DevOps is focused on the software delivery lifecycle. It aims to break down silos and create a more agile and efficient development process from code creation to deployment and maintenance. DevOps principles allow for faster delivery of code and more ownership of that code once it as been released.

Site Reliability Engineering, on the other hand, is a specific engineering discipline that focuses on ensuring the reliability, scalability, and availability of systems. SRE strives to strike a balance between reliability, performance, and cost of an environment in order to meet the predefined objectives for those systems.

If your goal is to deliver better software more efficiently, then DevOps is likely what you need. If, however, you are concerned with the reliability and performance of the infrastructure, then SRE may be the better choice.

While there is a lot of overlap in how each approaches the problems, be sure you understand what your end goal is before settling on a solution.

Roles

Another difference is that DevOps is a philosophical approach to software development while SRE is a specific role with defined responsibilities.

DevOps is a culture where developers and operations teams share responsibilities and work together to achieve common goals. Developers are involved in the operational aspects, and operations teams collaborate in the development process to improve the efficiency of the entire software lifecycle. Someone that works within a DevOps team will likely have a job title like Full-Stack Developer or something similar. 

SRE, on the other hand, is a specific role within an organization. Site Reliability Engineers have skills that cross the boundary between infrastructure and software. They focus on operations and their primary responsibility is to maximize the reliability of systems. They work on automation, monitoring, and incident response to continuously improve system reliability. Someone working on an SRE team will typically be called a Site Reliability Engineer.

You might want to think of it this way. SRE is about WHAT you are doing while DevOps is more about HOW you are doing it.

Error Budgets

SRE is heavily focused on availability. That is, minimizing unplanned downtime for a system. You have likely heard of five 9s as a measure of system availability. A Service Level Agreement (SLA) of five 9s means that the system must be available 99.999% of the time. This works out a TOTAL of 5 minutes of downtime each year. In SRE terms, that 5 minutes is the error budget.

Nearly everything that the SRE team does will be be to ensure that the 99.999% SLA is met. They have a budget of 5 minutes to work with during the year.

DevOps is not as focused on reliability. Remember, DevOps is concerned with the delivery of software. While uptime is certainly in the conversation, it is less important than other measures such as speed-to-market.

If your environment has a requirement to maintain a certain uptime agreement, then SRE might be the better choice.

DevOps is a cultural and organizational approach focused on breaking down barriers between development and operations for the purposes of improved software development. SRE is a specific engineering discipline with a primary focus on ensuring system reliability through practices like setting Service Level Objectives (SLOs), managing error budgets, and maintaining a blameless culture.

Both DevOps and SRE can complement each other and organizations may choose to adopt elements from both approaches. Just make sure you know where they differ so you can make the right choice for your team.