SLA, SLI, and SLO

A service-level agreement (SLA) is a contract between a cloud provider and a customer that guarantees a certain level of service. For example, an SLA might guarantee that a database will be available 99.9% of the time.

Imagine you are the owner of a business that relies heavily on a cloud-based customer relationship management (CRM) system to manage interactions with your clients. You sign an SLA with your cloud service provider, and it guarantees that the CRM system will be available and accessible to your team 99.9% of the time over the course of a year. This means that you expect no more than 8 hours and 45 minutes of downtime in a year, ensuring that your business operations run smoothly.

A service-level indicator (SLI) is a metric that is used to measure the performance of a service. For example, an SLI for a database might be the average response time for queries.

Let’s consider a video streaming platform. An SLI for such a platform could be...