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---
stage: Monitor
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group: Health
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info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
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---
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# Using variables **(FREE)**
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## Query variables
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Variables can be specified using double curly braces, such as `"{{ci_environment_slug}}"` ([added](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/20793) in GitLab 12.7).
Support for the `"%{ci_environment_slug}"` format was
[removed ](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/31581 ) in GitLab 13.0.
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Queries that continue to use the old format display no data.
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## Predefined variables
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GitLab supports a limited set of [CI/CD variables ](../../../ci/variables/README.md )
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in the Prometheus query. This is particularly useful for identifying a specific
environment, for example with `ci_environment_slug` . Variables for Prometheus queries
must be lowercase. The supported variables are:
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- `environment_filter`
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- `ci_environment_slug`
- `kube_namespace`
- `ci_project_name`
- `ci_project_namespace`
- `ci_project_path`
- `ci_environment_name`
- `__range`
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### environment_filter
`environment_filter` is automatically expanded to `container_name!="POD",environment="ENVIRONMENT_NAME"`
where `ENVIRONMENT_NAME` is the name of the current environment.
For example, a Prometheus query like `container_memory_usage_bytes{ {{environment_filter}} }`
becomes `container_memory_usage_bytes{ container_name!="POD",environment="production" }` .
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### __range
The `__range` variable is useful in Prometheus
[range vector selectors ](https://prometheus.io/docs/prometheus/latest/querying/basics/#range-vector-selectors ).
Its value is the total number of seconds in the dashboard's time range.
For example, if the dashboard time range is set to 8 hours, the value of
`__range` is `28800s` .
## User-defined variables
[Variables can be defined ](../../../operations/metrics/dashboards/yaml.md#templating-templating-properties ) in a custom dashboard YAML file.
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Variable names are case-sensitive.
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## Query variables from URL
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> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/214500) in GitLab 13.0.
GitLab supports setting custom variables through URL parameters. Surround the variable
name with double curly braces (`{{example}}`) to interpolate the variable in a query:
```plaintext
avg(sum(container_memory_usage_bytes{container_name!="{{pod}}"}) by (job)) without (job) /1024/1024/1024'
```
The URL for this query would be:
```plaintext
http://gitlab.com/< user > /< project > /-/environments/< environment_id > /metrics?dashboard=.gitlab%2Fdashboards%2Fcustom.yml& pod=POD
```
