Variables in Documentation Templates

This page describes the variables and channel-specific controls that are available for use in the documentation template associated with an alerting policy.

Using variables

In addition to Markdown, you can use variables of the form ${varname} to tailor the content of your documentation. When the documentation is sent with a notification, the string ${varname} will be replaced with the value of varname. The following screenshot shows the documentation included in an email notification, created from the documentation template described in Creating an alerting policy: Documentation:

Documentation in email

The following variables are available for use in documentation fields:

Variable Value
condition.name The REST resource name of the condition, such as projects/foo/alertPolicies/1234/conditions/5678
condition.display_name The display name of a condition, such as CPU usage increasing rapidly
metric.type The metric type, such as compute.googleapis.com/instance/cpu/utilization
metric.display_name The display name for the metric type, such as CPU utilization
metric.label.[KEY] The value of the metric label [KEY]1
policy.user_label.[KEY] The value of the user label [KEY]1,2
policy.name The REST resource name of the policy, such as projects/foo/alertPolicies/1234
policy.display_name The display name of a policy, such as High CPU rate of change
project The project ID of the Workspace, such as a-gcp-project
resource.project The project ID of the monitored resource of the alerting policy
resource.type The type of the monitored resource, such as api
resource.label.[KEY] The value of the resource label [KEY]1,3

1 For example, ${resource.label.zone} is replaced with the value of the zone label. The values of these variables are subject to grouping; see the following Notes for more information.
2 User labels in a policy can only be set by using the Monitoring API.
3 To retrieve the value of the project_id label on a monitored resource in the alerting policy, use ${resource.project}.

Notes:

  • Only the variables in the table are supported. You cannot combine them into more complex expressions, like ${varname1 + varname2}.
  • Values for some variables (for example resource.project, metric.label.[KEY], resource.label.[KEY], and metadata.user_label.[KEY]) are derived from time series. The values can be null if no values are returned from the time series query. One thing that can cause variables to have null values is if your alerting policy uses a cross-series aggregation (for example, calculating the SUM across each of the time-series that match the filter). When using a cross-series aggregation, any variables not used in grouping are dropped and will have null values if referenced in variable substitution.
  • To include the literal string ${ in your documentation, escape the $ symbol with a second $ symbol, and $${ will render as ${ in your documentation.
  • These variables are replaced by their values only in notifications sent through notification channels. In the Stackdriver Monitoring console, when the documentation is shown, you see the variables, not the values. Examples in the console include the descriptions of incidents and the preview of the documentation when creating an alerting policy.

Using channel controls

The text in the documentation field can also include special characters used by the notification channel itself to control formatting and notifications.

For example, Slack uses @ for mentions. You can use this to link the notification to a specific user. Suppose you include a string like this in the documentation field:

<@backendoncall> policy ${policy.display_name} triggered an incident

When the documentation field is received by the relevant Slack channel as part of the notification, this line triggers an additional message to the user backendoncall that, for example, the policy High CPU rate of change triggered an incident.

These additional options are specific to the channels; for more information on what may be available, consult the documentation provided by the channel vendor.

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