74effdcfcd
This documents the various knowledge needed to add new GitLab self-monitoring Prometheus metrics.
69 lines
2.6 KiB
Markdown
69 lines
2.6 KiB
Markdown
# Working with Prometheus Metrics
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## Adding to the library
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We strive to support the 2-4 most important metrics for each common system service that supports Prometheus. If you are looking for support for a particular exporter which has not yet been added to the library, additions can be made [to the `common_metrics.yml`](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/prometheus/common_metrics.yml) file.
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### Query identifier
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The requirement for adding a new metric is to make each query to have an unique identifier which is used to update the metric later when changed:
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```yaml
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- group: Response metrics (NGINX Ingress)
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metrics:
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- title: "Throughput"
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y_label: "Requests / Sec"
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queries:
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- id: response_metrics_nginx_ingress_throughput_status_code
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query_range: 'sum(rate(nginx_upstream_responses_total{upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) by (status_code)'
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unit: req / sec
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label: Status Code
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```
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### Update existing metrics
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After you add or change existing _common_ metric you have to create a new database migration that will query and update all existing metrics.
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NOTE: **Note:**
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If a query metric (which is identified by `id:`) is removed it will not be removed from database by default.
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You might want to add additional database migration that makes a decision what to do with removed one.
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For example: you might be interested in migrating all dependent data to a different metric.
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```ruby
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class ImportCommonMetrics < ActiveRecord::Migration[4.2]
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include Gitlab::Database::MigrationHelpers
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DOWNTIME = false
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def up
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::Gitlab::DatabaseImporters::CommonMetrics::Importer.new.execute
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end
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def down
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# no-op
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end
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end
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```
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## GitLab Prometheus metrics
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GitLab provides [Prometheus metrics](../administration/monitoring/prometheus/gitlab_metrics.md)
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to monitor itself.
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### Adding a new metric
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This section describes how to add new metrics for self-monitoring
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([example](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/15440)).
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1. Select the [type of metric](https://gitlab.com/gitlab-org/prometheus-client-mmap#metrics):
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- `Gitlab::Metrics.counter`
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- `Gitlab::Metrics.gauge`
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- `Gitlab::Metrics.histogram`
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- `Gitlab::Metrics.summary`
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1. Select the appropriate name for your metric. Refer to the guidelines
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for [Prometheus metric names](https://prometheus.io/docs/practices/naming/#metric-names).
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1. Update the list of [GitLab Prometheus metrics](../administration/monitoring/prometheus/gitlab_metrics.md).
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1. Trigger the relevant page/code that will record the new metric.
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1. Check that the new metric appears at `/-/metrics`.
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