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stats: add bootstrap annotations for stats flush and eviction #3562

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4183d8f
add bootstrap annotations
kyessenov Sep 4, 2025
3707c10
histogram bin sizes
kyessenov Sep 5, 2025
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43 changes: 43 additions & 0 deletions annotation/annotations.gen.go
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66 changes: 66 additions & 0 deletions annotation/annotations.pb.html
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29 changes: 29 additions & 0 deletions annotation/annotations.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -191,6 +191,35 @@ annotations:
resources:
- Pod

- name: sidecar.istio.io/statsFlushInterval
featureStatus: Alpha
description: Specifies the flush interval for push-based stat sinks, e.g. OTLP. Default interval is `5s`.
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qq: if this is only for push-based stats sinks, what about prometheus (pull based)?

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Flush interval doesn't matter for prometheus. However, eviction piggy backs on flush timer, and eviction works for prometheus.

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I don't get it. if it doesn't matter, but we evict when we flush, then it does matter...? And if the default is 5s, isn't that going to break prometheus?

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Envoy always runs a stats flush timer, regardless of prometheus. During that timer, server stats are published (e.g. memory allocations, etc), and some other work is done, e.g. eviction.

Prometheus endpoint can snip stats are any point through, in between flushes.

So flush impacts prometheus only indirectly, e.g. by updating/removing some metrics.

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Maybe more concretely... I send 1 request to foo.com. I get an istio_request_total metric for it.

When, with prometheus, will this metric stop showing up in /stats/prometheus with/without this annotation set?

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For flush annotation: it will show up immediately and stay forever.
For eviction annotation: same, but it will disappear after 2*eviction interval unless the metric gets another hit.

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Thanks! Sorry I was being a bit dense, github UI was hiding part of the PR

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@howardjohn @keithmattix can we move this forward?

deprecated: false
hidden: false
resources:
- Pod

- name: sidecar.istio.io/statsEvictionInterval
featureStatus: Alpha
description: Specifies the expiration interval for the Istio standard
metrics. This gets rounded to a multiple of the flush interval. A time
series is expected to be evicted after 2 iterations of this interval from
the last measurement.
deprecated: false
hidden: false
resources:
- Pod

- name: sidecar.istio.io/statsHistogramBins
featureStatus: Alpha
description: Specifies the bin size per time series for the Istio standard
metrics histograms. Reducing this value from the default `100` decreases
overall memory usage for sparse and/or high cardinality histograms.
deprecated: false
hidden: false
resources:
- Pod

- name: sidecar.istio.io/userVolume
featureStatus: Alpha
description: Specifies one or more user volumes (as a JSON array) to be added to
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