{ "api_version": "1", "kind": "dse_post", "self": "https://update.dsesecurity.com/api/v1/posts/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "item": { "id": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "slug": "dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job", "url": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "alternate_urls": { "markdown": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job.md", "json": "https://update.dsesecurity.com/api/v1/posts/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/" }, "title": "Distinguish a rejected Prometheus sample from a failed scrape job", "summary": "Can one oversized label cause all metrics from a Prometheus scrape job to disappear?", "format": { "slug": "guide", "name": "Guide" }, "priority": { "slug": "info", "name": "Information" }, "featured": false, "image": { "theme": "continuity-recovery", "label": "Continuity & recovery", "alt": "Paired infrastructure paths converging on a stable recovered service.", "card_url": "https://update.dsesecurity.com/assets/editorial/continuity-recovery-card.webp?v=1.8.20", "hero_url": "https://update.dsesecurity.com/assets/editorial/continuity-recovery-hero.webp?v=1.8.20", "social_url": "https://update.dsesecurity.com/assets/editorial/continuity-recovery-social-v2.jpg?v=1.8.20", "width": 2400, "height": 1350 }, "topics": [ { "slug": "business-continuity", "name": "Business Continuity", "url": "https://update.dsesecurity.com/topic/business-continuity/" }, { "slug": "it", "name": "IT", "url": "https://update.dsesecurity.com/topic/it/" } ], "author": { "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/#editorial-team", "type": "Organization" }, "publisher": { "name": "Detection Systems & Engineering", "url": "https://dsesecurity.com/" }, "published_at": "2026-09-10T00:26:43+00:00", "modified_at": "2026-09-10T01:40:02+00:00", "reviewed_on": "2026-09-09", "reading_minutes": 2, "word_count": 237, "potentially_affected": "Azure Monitor Prometheus collection investigating missing metrics caused by documented name and label limits.", "dse_recommendation": "Inspect the failing sample's label shape before treating a missing job as a workspace-wide ingestion problem.", "primary_source": { "name": "Troubleshoot collection of Prometheus metrics in Azure Monitor - Azure Monitor | Microsoft Learn", "url": "https://learn.microsoft.com/en-us/azure/azure-monitor/containers/prometheus-metrics-troubleshoot", "published_on": null, "authority": "Microsoft Learn" }, "publishing_principles": "https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/", "usage_info": "https://update.dsesecurity.com/usage/", "copyright_notice": "Copyright © 2026 Detection Systems & Engineering. All rights reserved.", "content_html": "

Source facts

\n

Microsoft’s Prometheus troubleshooting table documents different failure scopes. A label name above 511 characters, label value above 1,023 characters or more than 63 labels can fail the entire scrape job. A metric name above 511 characters instead drops the affected series. Labels differing only by case within one sample are treated as duplicates and that sample is dropped during ingestion. Microsoft Learn.

\n

Applicability

\n

Use these documented limits when a target exposes unexpected label shapes or metrics disappear after an exporter change. Establish whether the failure affects one series, one scrape job or a broader collection path before assigning a cause.

\n

DSE recommendation

\n

Inspect the failing sample’s label shape before treating a missing job as a workspace-wide ingestion problem. Have the exporter owner review generated label names, values and counts, especially values assembled from unbounded application input. Preserve a sanitized example and compare it with the documented limit that matches the observed failure. Correct the producer or approved collection configuration rather than merely increasing unrelated workspace capacity.

\n

Verification

\n

In a nonproduction reproduction, compare the target’s scrape status and expected series before and after correcting the offending shape. Check that unrelated metrics in the job return as intended. Record whether the observed result was a whole-job failure or a sample-level drop, and preserve the relevant collector or target diagnostic evidence. Do not infer the scope from an empty dashboard panel alone.

\n

Official references

\n

Microsoft Learn: Troubleshoot Prometheus collection. Source reviewed September 9, 2026.

", "content_text": "Source facts\nMicrosoft’s Prometheus troubleshooting table documents different failure scopes. A label name above 511 characters, label value above 1,023 characters or more than 63 labels can fail the entire scrape job. A metric name above 511 characters instead drops the affected series. Labels differing only by case within one sample are treated as duplicates and that sample is dropped during ingestion. Microsoft Learn.\nApplicability\nUse these documented limits when a target exposes unexpected label shapes or metrics disappear after an exporter change. Establish whether the failure affects one series, one scrape job or a broader collection path before assigning a cause.\nDSE recommendation\nInspect the failing sample’s label shape before treating a missing job as a workspace-wide ingestion problem. Have the exporter owner review generated label names, values and counts, especially values assembled from unbounded application input. Preserve a sanitized example and compare it with the documented limit that matches the observed failure. Correct the producer or approved collection configuration rather than merely increasing unrelated workspace capacity.\nVerification\nIn a nonproduction reproduction, compare the target’s scrape status and expected series before and after correcting the offending shape. Check that unrelated metrics in the job return as intended. Record whether the observed result was a whole-job failure or a sample-level drop, and preserve the relevant collector or target diagnostic evidence. Do not infer the scope from an empty dashboard panel alone.\nOfficial references\nMicrosoft Learn: Troubleshoot Prometheus collection. Source reviewed September 9, 2026.", "content_markdown": "## Source facts\n\nMicrosoft’s Prometheus troubleshooting table documents different failure scopes. A label name above 511 characters, label value above 1,023 characters or more than 63 labels can fail the entire scrape job. A metric name above 511 characters instead drops the affected series. Labels differing only by case within one sample are treated as duplicates and that sample is dropped during ingestion. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/azure-monitor/containers/prometheus-metrics-troubleshoot).\n\n## Applicability\n\nUse these documented limits when a target exposes unexpected label shapes or metrics disappear after an exporter change. Establish whether the failure affects one series, one scrape job or a broader collection path before assigning a cause.\n\n## DSE recommendation\n\nInspect the failing sample’s label shape before treating a missing job as a workspace-wide ingestion problem. Have the exporter owner review generated label names, values and counts, especially values assembled from unbounded application input. Preserve a sanitized example and compare it with the documented limit that matches the observed failure. Correct the producer or approved collection configuration rather than merely increasing unrelated workspace capacity.\n\n## Verification\n\nIn a nonproduction reproduction, compare the target’s scrape status and expected series before and after correcting the offending shape. Check that unrelated metrics in the job return as intended. Record whether the observed result was a whole-job failure or a sample-level drop, and preserve the relevant collector or target diagnostic evidence. Do not infer the scope from an empty dashboard panel alone.\n\n## Official references\n\n[Microsoft Learn: Troubleshoot Prometheus collection](https://learn.microsoft.com/en-us/azure/azure-monitor/containers/prometheus-metrics-troubleshoot). Source reviewed September 9, 2026." }, "json_ld": { "@context": "https://schema.org", "@graph": [ { "@type": "Organization", "@id": "https://dsesecurity.com/#organization", "name": "Detection Systems & Engineering", "alternateName": "DSE Security", "url": "https://dsesecurity.com/", "logo": { "@type": "ImageObject", "url": "https://update.dsesecurity.com/assets/dse-logo-20260812.png?v=1.8.20" } }, { "@type": "Organization", "@id": "https://update.dsesecurity.com/#editorial-team", "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/", "parentOrganization": { "@id": "https://dsesecurity.com/#organization" } }, { "@type": "WebSite", "@id": "https://update.dsesecurity.com/#website", "name": "DSE Updates", "alternateName": "DSE Security Knowledge Hub", "url": "https://update.dsesecurity.com/", "inLanguage": "en-US", "publisher": { "@id": "https://dsesecurity.com/#organization" }, "potentialAction": { "@type": "SearchAction", "target": { "@type": "EntryPoint", "urlTemplate": "https://update.dsesecurity.com/?q={search_term_string}" }, "query-input": "required name=search_term_string" } }, { "@type": "WebPage", "@id": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "url": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "isPartOf": { "@id": "https://update.dsesecurity.com/#website" }, "lastReviewed": "2026-09-09" }, { "@type": "BreadcrumbList", "@id": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/#breadcrumbs", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "DSE Updates", "item": "https://update.dsesecurity.com/" }, { "@type": "ListItem", "position": 2, "name": "Distinguish a rejected Prometheus sample from a failed scrape job", "item": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/" } ] }, { "@type": [ "Article", "TechArticle" ], "@id": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/#article", "identifier": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "url": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/", "headline": "Distinguish a rejected Prometheus sample from a failed scrape job", "description": "Can one oversized label cause all metrics from a Prometheus scrape job to disappear?", "abstract": "Can one oversized label cause all metrics from a Prometheus scrape job to disappear?", "articleBody": "Source facts\nMicrosoft’s Prometheus troubleshooting table documents different failure scopes. A label name above 511 characters, label value above 1,023 characters or more than 63 labels can fail the entire scrape job. A metric name above 511 characters instead drops the affected series. Labels differing only by case within one sample are treated as duplicates and that sample is dropped during ingestion. Microsoft Learn.\nApplicability\nUse these documented limits when a target exposes unexpected label shapes or metrics disappear after an exporter change. Establish whether the failure affects one series, one scrape job or a broader collection path before assigning a cause.\nDSE recommendation\nInspect the failing sample’s label shape before treating a missing job as a workspace-wide ingestion problem. Have the exporter owner review generated label names, values and counts, especially values assembled from unbounded application input. Preserve a sanitized example and compare it with the documented limit that matches the observed failure. Correct the producer or approved collection configuration rather than merely increasing unrelated workspace capacity.\nVerification\nIn a nonproduction reproduction, compare the target’s scrape status and expected series before and after correcting the offending shape. Check that unrelated metrics in the job return as intended. Record whether the observed result was a whole-job failure or a sample-level drop, and preserve the relevant collector or target diagnostic evidence. Do not infer the scope from an empty dashboard panel alone.\nOfficial references\nMicrosoft Learn: Troubleshoot Prometheus collection. Source reviewed September 9, 2026.", "datePublished": "2026-09-10T00:26:43+00:00", "dateModified": "2026-09-10T01:40:02+00:00", "mainEntityOfPage": { "@id": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/" }, "inLanguage": "en-US", "isAccessibleForFree": true, "author": { "@type": "Organization", "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/#editorial-team" }, "publisher": { "@id": "https://dsesecurity.com/#organization" }, "image": { "@type": "ImageObject", "@id": "https://update.dsesecurity.com/updates/dse-20260909-313-distinguish-a-rejected-prometheus-sample-from-a-failed-scrape-job/#primaryimage", "url": "https://update.dsesecurity.com/assets/editorial/continuity-recovery-social-v2.jpg?v=1.8.20", "contentUrl": "https://update.dsesecurity.com/assets/editorial/continuity-recovery-social-v2.jpg?v=1.8.20", "width": 1200, "height": 630, "caption": "Distinguish a rejected Prometheus sample from a failed scrape job" }, "articleSection": [ "Business Continuity", "IT" ], "keywords": [ "Business Continuity", "IT", "Guide", "Information priority" ], "genre": "Guide", "about": [ { "@type": "Thing", "name": "Business Continuity", "url": "https://update.dsesecurity.com/topic/business-continuity/" }, { "@type": "Thing", "name": "IT", "url": "https://update.dsesecurity.com/topic/it/" } ], "wordCount": 237, "timeRequired": "PT2M", "publishingPrinciples": "https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/", "usageInfo": "https://update.dsesecurity.com/usage/", "copyrightHolder": { "@id": "https://dsesecurity.com/#organization" }, "copyrightNotice": "Copyright © 2026 Detection Systems & Engineering. All rights reserved.", "citation": { "@type": "CreativeWork", "name": "Troubleshoot collection of Prometheus metrics in Azure Monitor - Azure Monitor | Microsoft Learn", "url": "https://learn.microsoft.com/en-us/azure/azure-monitor/containers/prometheus-metrics-troubleshoot" } } ] } }