Find and fix rule and monitor evaluation failures

Recording rules and monitors might not evaluate properly, leaving you with missing data or errors that weren't caught.

You can view your recording rule or monitor failures in the Chronosphere app, or with Chronoctl.

Delete low value rules

Use the Telemetry Usage Analyzer to review metrics used in failing rules or monitors. If the metric is low value, deleting the failing rule or monitor might make more sense than fixing it.

Common failures and solutions

Here are some common errors and solutions to help you fix failing rules and monitors:

• Prometheus runtime error: Vector contains metrics with the same labelset after applying labels
• Prometheus runtime error: Found duplicate series for the match group
• Prometheus runtime error: Template errors
• Resources exhausted: The query exceeded the allowable resource limit
• Query timed out: context deadline exceeded

Vector contains metrics with the same labelset after applying labels

Prometheus requires all time series returned from a monitor query or a reporting rule be fully unique, meaning the entire set of label:value pairs must differ across a time series. If metrics have the same labels after applying alert or rule labels, a collision occurs.

Similar to Prometheus, Chronosphere takes monitor or recording rule labels and overrides the label pairs from all returned time series.

The error message Vector contains metrics with the same labelset after applying alert (or rule) labels indicates a monitor or recording rule label:value collision.

For example:

• Monitor or Recording Rule labels: {"service": "gateway"}
• Fetched time series labels: {"action": "http_get", "service": "ui-console"}
• Resulting time series: {"action": "http_get", "service": "gateway"}

In this instance, the ui-console label is overridden to gateway after the monitor or recording rule labels apply. The error occurs in a situation where collected values look like:

• Monitor or Recording Rule labels: {"service": "gateway"}
• Fetched time series 1: {"action": "http_get", "service": "ui-console"}
• Fetched time series 2: {"action": "http_get", "service": "backend-server"}

Processing rewrites these time series to:

• Resulting time series 1: {"action": "http_get", "service": "gateway"}
• Resulting time series 2: {"action": "http_get", "service": "gateway"}

After applying the monitor or recording rule override {"service": "gateway"}, the resulting time series are an exact match, which causes an error.

Solutions

Use one of the following methods to resolve the error:

• Use the Prometheus label_replace (opens in a new tab) operator to change the underlying label name being overwritten.
• Remove the monitor or recording rule label.

Found duplicate time series

The error message Found duplicate series for the match group indicates two time series being joined together, but the series don't have the same labels. For example, one time series might have a host or instance label, while the other doesn't.

Review the error message and identify the problematic labels.

Solutions

Use one of the following methods to address this issue:

• Remove the labels from the offending metric. If the labels aren't used in dashboards, monitors, recording rules, or queries, you can create a rollup rule to remove the labels from the metric.
• Update the query to exclude the problematic labels. If other resources use the label, or you want to keep the labels for any other reason, update the query using PromQL functions, such as group, sum, or max, and use the without option to exclude the labels. For example, group(test1) without (host, instance). Refer to the PromQL documentation (opens in a new tab) for the behavior of each function.

Template errors

Invalid Prometheus query templates display errors like undefined variable "$labels".

Solutions

Chronosphere attempts to parse your queries using go template syntax (opens in a new tab). This error typically means you have a block that looks like {{ <your text here> }} somewhere in the raw query. Remove those blocks to fix this issue.

The query exceeded the allowable resource limit

Resource exhaustion occurs when a query has requested more time series than system resources can support. For example, a query that returns millions of results can't process.

Solutions

Use one of the following methods to address this issue:

• Reduce the number of time series returned by the query by adding more label filters. This might not return all of the results you need, so you might need to write multiple recording rules and then update your dashboards and monitors to use the appropriate metric.
• Chronosphere provides rollup rules you can use to remove labels from metrics and aggregate values together, reducing cardinality. Rollup rules can dramatically reduce the number of time series for a particular metric, which might let your query complete.

Context deadline exceeded

This error is functionally similar to queries exceeding the allowable resource limit. Correct these errors with the same solutions.