Defining service level objectives (SLOs) is an element of SRE that identifies the reliability expectations of customers. To achieve goal and reliability, it creates a communication process between product and engineering on reliability. Team members need to set an objective and plan to achieve it. The objective can be 95% or 98% availability, but 100% availability is impossible as the production system can change anytime. So, instead of perfection, SLO focuses on making customers happy with the right level of reliability.
SLO systems do not prefer perfection. Why? 100% reliability means no changes in the production process. So they can’t add new features which stop organizations from reaching more customers. That is why meeting a certain level of reliability is the objective. This article talks about SLO, its purpose, and its monitoring system.
What is SLO?
SLO is a process that quantifies customers’ happiness and expectation. Seeing the percentage, developers can decide on their actions. When developers meet customers’ expectations on reliability, they can offer extra value by adding a new feature to the product.
Purpose of an SLO
SLO measures customers’ happiness. From the measurement, developers can create a product with the perfect reliability, engineering, and leadership. Thus it protects the business from violating SLA rules.
Customers demand a product that ensures a balance between innovation and reliability. As the IT business world is changing quickly, adding a new feature is a must. Businesses also need to innovate and add new features to survive and earn profit. The features need to be reliable enough to use at any time. Here, SLO helps teams by providing measurements to create a balance between reliability and feature velocity.
Defining the SLO for a Service
Most used two approaches of defining the SLO for service are:
· Engineering Centric Approach
It is a process where teams first define the SLI, then SLO. At last, they monitor and report to the developers based on SLO. Using this approach is a bit confusing and complicated. So companies prefer using the second approach.
· Product-Centric Approach
Here, teams first define the user journey with the company. Then they choose and define SLI, SLO, Create an error budget, monitor, and report to the developers based on SLO. Developers can re-evaluate the SLO anytime.
SREs are responsible for monitoring SLO. The SRE team can make their monitoring system and error budget policies. The system auto sends alerts when it finds unexpected percentages in the error budget. To define SLO, members first need to find SLI metrics. Then they identify whether the SLO is at risk or not. If the SLO is at risk, SRE works with developers and operators to meet the required SLO.
Monitoring SLIs over time is the first step of the process. Then it is compared with the SLOs. Teams can find higher, mid, or low-level risks. Based on the risk level SREs take action. Ideally, this process should be carried out on a periodic basis. Without SLO, SREs will not be able to detect risk or prevent it.
Organizations may find it challenging to define the SLO. But with an excellent SRE team, the process becomes more accessible and smoother. Also, the business can enjoy long-term benefits.