SLOs or Service Level Objectives are part of SLA agreements where promises are made on specific metrics within an SLA agreement. SLO is made by the service provider to set up the expectations with the most important metrics associated with the service. They are often used to assess and improve services and quality internally, as well as externally. And, thus acts as one of the primary KPIs for the tech team.
Typically, there is no “right” value for an SLO, and is just basis the business/customer experience needs — so unless a service is highly critical, runs at a large scale, or directly impacts revenue, these might be informal/implicit.
Say you’re the owner of the order placement service, and another team member owns an upstream API, say, authentication service. There are internal contracts set on what would be the latency/response time for a request sent from an order placement service, to an authentication service.
When you charge an external client for API usage or have an integration that has a critical dependency with a third party, you might explicitly define an SLO within a contract (SLA).
Here’s an example document of an SLO by the Google SRE team
SLOs are internal performance goals, while SLAs (Service Level Agreements) are formal customer contracts defining service standards and terms — this might or might not include SLOs. Additionally, SLIs refer to the “actual” value of an SLO, when measured for a specific time interval.
The difference between the SLO commitment/ goal and the actual SLI is often measured using an error budget.
You can read more about SLAs, SLIs, and error budgets here.
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Our team has deep experience in helping companies set up their monitoring and observability stack, so if you need any assistance in setting it up, we are happy to assist. You can reach out to us, here.