Bug 2034192 - Prometheus fails to insert reporting metrics when the sample limit is met
Summary: Prometheus fails to insert reporting metrics when the sample limit is met
Alias: None
Product: OpenShift Container Platform
Classification: Red Hat
Component: Monitoring
Version: 4.10
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
: 4.10.0
Assignee: Arunprasad Rajkumar
QA Contact: Junqi Zhao
Brian Burt
Depends On:
TreeView+ depends on / blocked
Reported: 2021-12-20 11:33 UTC by Simon Pasquier
Modified: 2022-03-10 16:35 UTC (History)
5 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Previously, if reporting metrics failed due to reaching the configured sample limit, the metrics target would still appear with a status of `Up` in the web console UI even though the metrics were missing. With this release, Prometheus bypasses the sample limit setting for reporting metrics, and the metrics now appear regardless of the sample limit setting.
Clone Of:
Last Closed: 2022-03-10 16:35:23 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Github openshift cluster-monitoring-operator pull 1522 0 None open Bug 2034192: [bot] Automated dependencies version update 2021-12-21 07:27:58 UTC
Github openshift prometheus pull 117 0 None open Bug 2034192: [bot] Bump openshift/prometheus to v2.32.1 2021-12-20 13:14:29 UTC
Red Hat Product Errata RHSA-2022:0056 0 None None None 2022-03-10 16:35:35 UTC

Description Simon Pasquier 2021-12-20 11:33:31 UTC
Description of problem:
When a service monitor defines a sample limit (which is possible for user-workload monitoring), the reporting metrics (up, scrape_samples_scraped, ...) may not be inserted by Prometheus if the number of samples exposed by the target is close to the limit.
See https://github.com/prometheus/prometheus/issues/9990 for the details.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Follow the OCP documentation to deploy the sample application which exposes only one metric.
2. Add a sample limit of 1 to the application's service monitor

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
    k8s-app: prometheus-example-monitor
  name: prometheus-example-monitor
  namespace: ns1
  - interval: 30s
    port: web
    scheme: http
  sampleLimit: 1
      app: prometheus-example-app

Actual results:
The target is scraped successfully (no target down) but the up metric is missing (like the other reporting metrics).

Expected results:
Reporting metrics should be present.

Additional info:
Fixed in Prometheus v2.32.1.

Comment 5 Junqi Zhao 2021-12-22 03:51:53 UTC
tested with 4.10.0-0.nightly-2021-12-21-130047, followed steps in comment 0, could see the up metric
# oc -n openshift-monitoring logs -c prometheus prometheus-k8s-0
ts=2021-12-21T23:54:33.692Z caller=main.go:532 level=info msg="Starting Prometheus" version="(version=2.32.1, branch=rhaos-4.10-rhel-8, revision=2003b6cb83d933ad154a6dcd6bc6b497488b8501)"

# oc -n openshift-user-workload-monitoring exec -c prometheus prometheus-user-workload-0 -- cat /etc/prometheus/config_out/prometheus.env.yaml
- job_name: serviceMonitor/ns1/prometheus-example-monitor/0
  - source_labels:
    - __tmp_hash
    regex: 0
    action: keep
  sample_limit: 1
  - target_label: namespace
    replacement: ns1

# oc -n openshift-user-workload-monitoring exec -c prometheus prometheus-user-workload-0 -- cat /etc/prometheus/config_out/prometheus.env.yaml
# oc -n openshift-monitoring exec -c prometheus prometheus-k8s-0 -- curl -k -H "Authorization: Bearer $token" 'https://thanos-querier.openshift-monitoring.svc:9091/api/v1/query?query=up%7Bnamespace%3D%22ns1%22%7D' | jq
  "status": "success",
  "data": {
    "resultType": "vector",
    "result": [
        "metric": {
          "__name__": "up",
          "endpoint": "web",
          "instance": "",
          "job": "prometheus-example-app",
          "namespace": "ns1",
          "pod": "prometheus-example-app-8659789999-nwh2k",
          "prometheus": "openshift-user-workload-monitoring/user-workload",
          "service": "prometheus-example-app"
        "value": [

Comment 8 errata-xmlrpc 2022-03-10 16:35:23 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: OpenShift Container Platform 4.10.3 security update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


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