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Diffstat (limited to 'doc/development/application_slis/index.md')
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diff --git a/doc/development/application_slis/index.md b/doc/development/application_slis/index.md index f48088a6e08..30bd6011a67 100644 --- a/doc/development/application_slis/index.md +++ b/doc/development/application_slis/index.md @@ -14,40 +14,40 @@ and their success close to the implementation and allows the people building features to easily define how these features should be monitored. -Defining an SLI causes 2 -[Prometheus counters](https://prometheus.io/docs/concepts/metric_types/#counter) -to be emitted from the rails application: - -- `gitlab_sli:<sli name>:total`: incremented for each operation. -- `gitlab_sli:<sli_name>:success_total`: incremented for successful - operations. - ## Existing SLIs 1. [`rails_request`](rails_request.md) 1. `global_search_apdex` 1. `global_search_error_rate` 1. `global_search_indexing_apdex` +1. [`sidekiq_execution`](sidekiq_execution.md) ## Defining a new SLI -An SLI can be defined using the `Gitlab::Metrics::Sli::Apdex` or -`Gitlab::Metrics::Sli::ErrorRate` class. These work in broadly the same way, but -for clarity, they define different metric names: +An SLI can be defined with the `Gitlab::Metrics::Sli::Apdex` or +`Gitlab::Metrics::Sli::ErrorRate` class. When you define an SLI, two +[Prometheus counters](https://prometheus.io/docs/concepts/metric_types/#counter) +are emitted from the Rails application. Both counters work in broadly the same way and contain a total operation count. `Apdex` uses a success rate to calculate a success ratio, and `ErrorRate` uses an error rate to calculate an error ratio. -1. `Gitlab::Metrics::Sli::Apdex.new('foo')` defines: - 1. `gitlab_sli:foo_apdex:total` for the total number of measurements. - 1. `gitlab_sli:foo_apdex:success_total` for the number of successful +The following metrics are defined: + +- `Gitlab::Metrics::Sli::Apdex.new('foo')` defines: + - `gitlab_sli_foo_apdex_total` for the total number of measurements. + - `gitlab_sli_foo_apdex_success_total` for the number of successful measurements. -1. `Gitlab::Metrics::Sli::ErrorRate.new('foo')` defines: - 1. `gitlab_sli:foo:total` for the total number of measurements. - 1. `gitlab_sli:foo:error_total` for the number of error - measurements - as this is an error rate, it's more natural to talk about - errors divided by the total. +- `Gitlab::Metrics::Sli::ErrorRate.new('foo')` defines: + - `gitlab_sli_foo_total` for the total number of measurements. + - `gitlab_sli_foo_error_total` for the number of error + measurements. Because this metric is an error rate, + errors are divided by the total number. As shown in this example, they can share a base name (`foo` in this example). We recommend this when they refer to the same operation. +You should use `Apdex` to measure the performance of successful operations. You don't have to measure the performance of a failing request because that performance should be tracked with `ErrorRate`. For example, you can measure whether a request is performing within a specified latency threshold. + +You should use `ErrorRate` to measure the rate of unsuccessful operations. For example, you can measure whether a failed request returns an HTTP status greater than or equal to `500`. + Before the first scrape, it is important to have [initialized the SLI with all possible label-combinations](https://prometheus.io/docs/practices/instrumentation/#avoid-missing-metrics). This avoid confusing results when using these counters in calculations. |