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https://issues.apache.org/jira/browse/NIFI-10666?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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René Zeidler updated NIFI-10666:
--------------------------------
Environment:
Windows Server 2019 Version 1809
> PrometheusReportingTask does not use UTF-8 encoding on /metrics/ endpoint
> -------------------------------------------------------------------------
>
> Key: NIFI-10666
> URL: https://issues.apache.org/jira/browse/NIFI-10666
> Project: Apache NiFi
> Issue Type: Bug
> Components: Extensions
> Affects Versions: 1.16.3
> Environment: Windows Server 2019 Version 1809
> Reporter: René Zeidler
> Priority: Minor
> Attachments: missing-header.png
>
>
> We have created a default PrometheusReportingTask for our NiFi instance and
> tried to consume the metrics with Prometheus. However, Prometheus threw the
> following error:
> {code:java}
> ts=2022-10-19T12:25:18.110Z caller=scrape.go:1332 level=debug
> component="scrape manager" scrape_pool=nifi-cluster
> target=http://***nifi***:9092/metrics msg="Append failed" err="invalid UTF-8
> label value" {code}
> Upon further inspection, we noticed that the /metrics/ endpoint exposed by
> the reporting task does not use UTF-8 encoding, which is required by
> Prometheus.
> Our flow uses non-ASCII characters (in our case German umlauts like "ü"). As
> a workaround, removing those characters fixes the Prometheus error, but this
> is not practical for a large flow in German language.
> Opening the /metrics/ endpoint in a browser confirms that the encoding used
> is not UTF-8:
> {code:java}
> > document.characterSet
> 'windows-1252' {code}
> ----
> The responsible code might be here:
> [https://github.com/apache/nifi/blob/2be5c26f287469f4f19f0fa759d6c1b56dc0e348/nifi-nar-bundles/nifi-prometheus-bundle/nifi-prometheus-reporting-task/src/main/java/org/apache/nifi/reporting/prometheus/PrometheusServer.java#L67]
> The PrometheusServer used by the reporting task uses an OutputStreamWriter
> with the default encoding, instead of explicitly using UTF-8. The
> Content-Type header set in that function also does not get passed along (see
> screenshot)
> ----
> Our cluster is still on 1.16.3, but once we update to 1.18.0 we can update
> this report to confirm that the issue still persists. Considering that there
> were no code changes in the Prometheus reporting task, it is likely that the
> issue still persists in the current version.
> If someone can confirm this before we update, feel free to update the issue :)
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