Site Reliability Engineering (SRE)

Site Reliability Engineering (SRE) is a practice that emerged at Google because of its need for highly reliable and scalable systems. SRE unifies operations and development teams and implements DevOps principles to ensure system reliability, scalability, and performance.

There’s plenty of documentation on tactics for adopting automation and implementing infrastructure as code, but practical ops-focused SRE best practices based on real-world experience are harder to find. This article will explore 6 SRE best practices based on feedback from SREs and technical subject matter experts. Here is a list of topics we will cover.

SRE Best Practices

The six SRE best practices below are based on feedback from experienced SREs and focus on the operational side of site reliability engineering.

Define the role of the SRE

The Site Reliability Engineer, also called SRE; has several responsibilities:

• Designing systems to monitor, automate, and achieve the highest uptime with the lowest operational effort
• Enabling developers to iterate and move fast simultaneously
• Incident management
• Performing root cause analysis (RCA)
• Conducting post-mortems (more on these later in the article)
• Creating documentation to minimize tribal knowledge

SREs should spend most of their time automating their tasks to avoid having to be constantly working “toil”. Toil is a catchall term for operational tasks that involve repetitive manual configuration or lack long-term strategic value. Without automation, toil requires the engineering team’s time. With automation, engineers can focus on more complex tasks.

This diagram represents the optimal time allocation for an SRE engineer.

Automate toil and leave time for strategic tasks

To avoid wasting valuable engineering time, SREs should work on automating every repetitive task, so teams focus less on toil and more on innovation. SREs use scripts, programs, and frameworks to automate and monitor those tasks.

Within high-performing teams, eliminating toil is a core SRE function. From a tactical perspective, there are many ways to implement this best practice. The key is to limit wasting human time spent working on simple things automation can handle.

Monitor using SLIs and SLOs

Effective monitoring is a crucial part of SRE. Metrics should be as close to the user as possible since most businesses care more about user experience. Organizations should define their most important metrics. Then, SREs use these metrics to build the three key indicators: SLIs, SLOs, and SLAs.

SLIs: Service Level Indicators

SLIs are used to collect metrics in standardized ways. Here is a breakdown of common SLI types.

SLOs: Service Level Objectives

SLOs are the goals the organization must accomplish and are formulated using the service level indicators (SLI) explained in the previous section. These should be published internally in a place easily accessible for technical and non-technical stakeholders.

SLAs: Service Level Agreements

SLAs are contracts with clients/consumers about what to expect from the service, usually legally binding and with monetary implications if not met.

Maintain a transparent status page

Customers need to understand the system's status at all times. If there's an outage on a system, the customer has to know about it as soon as possible. That helps build trust and prevents them from troubleshooting an issue they cannot control.

Status pages reflect the status of services in real-time. They should be clear and concise and have a color-coded indicator for each service exposed to customers. In case of failure, it should immediately report which services are failing and why. It is always great to accompany it with an email or RSS notification.

Categorize incident severities

With enough time and complexity, errors happen. When they do, they must be addressed in an organized manner.

Incidents have different severities: generally, those are P0, P1, P2, and P3. Severity determines the action to be taken and response time.

Conduct post-mortems and share them publicly

Shortly after an incident, SREs should do two things:

• Address the issues: Critical errors are patched or hot-fixed in an improvised way, and it is usually not a permanent solution. If that is the case, those should be placed in the backlog to be revisited by the development teams. SREs should also review issues not fixed on-call during working hours.
• Draft a post-mortem: Post-mortems are a briefing of what happened during the incident. These help us get all the information from the incident, what happened, why, and how to prevent them in the future. Thus, every post-mortem should have clear documentation and action items placed in a backlog and prioritized according to the severity.

It is also a great idea to share post-mortems with the public since it helps bring transparency and strengthen their trust.