What is a composite SLO?
Composite SLOs allow aggregating multiple SLO objectives within a single SLO to represent an overall reliability performance view of your service. With this approach, you can group related SLIs into a single SLO to capture the customer’s holistic experience.
You can combine a set of objectives within a single SLO into a composite SLO. As you can define up to 12 objectives for an SLO, for example, in addition to creating an SLO for a piece of infrastructure or an SLO based on the latency of a shopping cart page, you can use composite SLOs to build an SLO focused on the end-to-end purchase experience.
Composite SLOs are grouped under projects and services.
Each SLO you define can only be part of one composite SLO.
Composite error budget calculation method
Composite SLOs have a new error budget calculation method called the composite error budget. It aggregates the error budgets of all the objectives in the SLO. Here's a glance of some rules that underlie changes in the calculation methods:
- The composite error budget burns if the error budget for any of the SLO objectives within the composite SLO is burning.
- For a time slice SLO, this is binary depending on whether it was a good or bad minute. If it was a bad minute for any individual objective, it’s considered a bad minute for the composite SLO.
- For an occurrences SLO, the composite error budget is calculated based on the error budget burn rate which measures how fast the error budget is being consumed following the
greater thancondition. The default burn rate value is 1x and can be customized.
