docs:Add support rule evaluation via query frontend docs #6200
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SungJin1212
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| frontend_address: query-frontend.svc.cluster.local:9095 | ||
| ``` | ||
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| In addition, you can configure gRPC client (Ruler -> Query Frontend) config via args: |
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I think it is unnecessary to list all configuration flags. This adds extra complexity for users who read this doc as I expect that most of the case default values should be good enough.
Is it possible to use a link to redirect to the frontend client configurations?
| backoff_config: | ||
| min_period: 100ms | ||
| max_period: 10s | ||
| max_retries: 10 |
| ## Pros and Cons | ||
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| ### Pros | ||
| The rule evaluation performance is improved as we can use Query Frontend features like the vertical query sharding. |
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In terms of performance, I think it is complex and it is not always true to say evaluation performance is improved.
By evaluating rules through Query Frontend, there are more hops in this path. Ruler -> Query Frontend -> Query Scheduler -> Querier -> Ingester/Store Gateway.
Query Frontend/Query Scheduler has a query queue and Querier pulls queries from the queue to execute. If there are not enough queriers, add rule queries to this path could cause query starvation problem and rules cannot get evaluated. I think this is something to call out in this doc.
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| ### Pros | ||
| The rule evaluation performance is improved as we can use Query Frontend features like the vertical query sharding. | ||
| The ruler can use fewer resources as it doesn't need to initialize the querier anymore. |
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This sounds vague to me. You mean in the code Ruler doesn't need to intialize the querier struct? I suggest rewording it to something like:
Ruler can use fewer resources as it doesn't need to run query engine to evaluate rules.
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Yes, what I mean is that. Let me fix it.
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| ## How to enable | ||
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| By default, the Ruler queries to the Ingesters for evaluating rules (alerting rules or recording rules). If you have set `-ruler.frontend-address` then the Ruler query to the Query Frontend for evaluation rules. |
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the Ruler queries the Ingesters.
the Ruler queries the Query Frontend.
Ruler queries both Ingesters and Store Gateway depending on the Rule time range.
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Signed-off-by: SungJin1212 <[email protected]>
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@yeya24 |
What this PR does:
Add docs on configuring Ruler to evaluate rules via Query Frontend and the pros and cons of this feature.
Which issue(s) this PR fixes:
Fixes #6198
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]