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Documentation Grafana Mimir Configure Configure queries to block

Configure queries to block

In certain situations, you might want to control what queries are being sent to your Mimir installation. These queries might be intentionally or unintentionally expensive to run, and they might affect the overall stability or cost of running your service.

You can block queries using per-tenant overrides:

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overrides:
  "tenant-id":
    blocked_queries:
      # block this query exactly
      - pattern: 'sum(rate(node_cpu_seconds_total{env="prod"}[1m]))'

      # block any query matching this regex pattern
      - pattern: '.*env="prod".*'
        regex: true

The blocking is enforced on instant and range queries as well as remote read queries.

For instant and range queries the pattern is evaluated against the query, for remote read requests, the pattern is evaluated against each set of matchers, as if the matchers formed a vector selector. If any set of matchers is blocked, the whole remote read request is rejected.

For example the remote read query that contains the matcher __name__ regex matched to foo.* is interpreted as {__name__=~"foo.*"}. To restrict the blocking to such selectors, include the curly braces in your pattern, e.g. \{.*foo.*\}.

To set up runtime overrides, refer to runtime configuration.

Format queries to block

Use Mimirtool’s mimirtool promql format <query> command to apply the Prometheus formatter to a query for use in a blocked query pattern.

Queries received by Mimir are parsed into PromQL expressions before blocking is applied. The pattern from the blocked queries is compared against the formatted representation of the parsed query, in order to allow consistent query blocking behavior regardless of formatting differences in the submitted queries.

Among other transformations the Prometheus formatter may reorder operators, remove empty selector braces, and eliminate newlines, extraneous whitespace, and comments.

Formatted query examples

Empty selector braces removed:

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mimirtool promql format 'foo{}'

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foo

Operators reordered:

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mimirtool promql format 'sum(container_memory_rss) by (namespace)'

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sum by (namespace) (container_memory_rss)

Newlines, extra whitespace, and comments eliminated:

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mimirtool promql format '
rate(
  metric_counter[15m] # comment 1
) /
rate(
  other_counter[15m] # comment 2
)
'

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rate(metric_counter[15m]) / rate(other_counter[15m])

View blocked queries

Blocked queries are logged, as well as counted in the cortex_query_frontend_rejected_queries_total metric on a per-tenant basis.