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Observability Sre Triage

ElasticOfficialCreated by elastic

  • Skill
  • Workflow
  • Cloud and DevOps
  • Apache-2.0
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From the author

Triage a degraded or suspect service end to end: read SLO status and burn rate, check active alerting rules and ML anomalies, measure throughput, latency, and error rate, assess dependency health and infrastructure saturation, and funnel logs down to the failures that explain it. Use when someone asks whether a service is healthy, why it is slow or erroring, what is in its logs, or which attribute distinguishes the requests that are failing. Also use when someone asks for the query behind any of those signals — throughput, latency percentiles, error rate, dependency health, or log volume — over APM/OTel traces, metrics, or logs.
— the description by elastic

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a structured, hierarchical approach to triaging service health. It guides the agent through a systematic investigation process, starting from high-level contract violations (SLOs and alerts) down to granular telemetry (golden signals, dependency health, infrastructure metrics, and log funnels). It is designed to help SREs and developers quickly determine if a service is healthy, degraded, or unhealthy, and to identify the root cause by correlating telemetry across traces, metrics, and logs.

What it does

  • Evaluates service health against SLO status and active alerting rules.
  • Measures golden signals including throughput, latency, and error rates.
  • Assesses dependency health and infrastructure saturation.
  • Funnels noisy log streams to isolate specific failure patterns.
  • Identifies subpopulations or attributes contributing to service degradation.
  • Provides a definitive verdict of healthy, degraded, or unhealthy based on evidence.

When to use it

  • When investigating reports of slow, erroring, or unresponsive services.
  • During incident response to determine the scope and cause of a service degradation.
  • When needing to correlate service performance with infrastructure or dependency issues.
  • When analyzing log data to explain specific service failures.

Advantages

  • Reduces mean time to resolution by following a standardized, evidence-based triage hierarchy.
  • Prevents speculation by requiring data-backed conclusions.
  • Efficiently narrows down large log volumes to actionable error patterns.
  • Provides clear, consistent verdicts based on agreed-upon reliability contracts.

Usage examples

“Is the checkout service healthy?”
The agent will check SLO status, active alerts, and golden signals to provide a verdict and supporting evidence.
“Why is the frontend service slow?”
The agent will compare current latency percentiles against a prior window and check dependency health to localize the bottleneck.
“The cart service logs look bad, what is happening?”
The agent will execute a log funnel to exclude noise and isolate the specific error patterns explaining the degradation.
“An alert fired on the api-gateway, what is the cause?”
The agent will identify the firing rule, verify its parameters, and analyze the underlying metrics to confirm the incident.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/elastic/observability-sre-triage/download
  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip observability-sre-triage.zip -d .agents/skills

Documentation by elastic

SRE Service Triage

Decide whether a service is healthy, degraded, or unhealthy, and say why. Triage is a hierarchy, not a checklist: SLOs and alerts define whether the service is failing its contract, trace-derived golden signals describe how it is failing, dependencies and infrastructure explain where the failure comes from, and logs supply the sentence you put in the incident channel. Work down the hierarchy until the evidence supports a verdict, then stop.

For authoring and tuning SLO definitions, burn-rate rules, and alert thresholds, use the observability-service-reliability skill. This skill only reads that state. For Kubernetes workload, node, or control-plane diagnosis — restart loops, OOM kill confirmation, node pressure, admission rejections, stuck rollouts — hand off to the observability-k8s-investigation skill. This skill checks whether a Kubernetes-hosted service is saturated; it does not diagnose why the pod or the node behind it is failing.

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Environment Configuration

This skill executes Elasticsearch operations through the elastic CLI. If the elastic CLI is not installed, tell the user what it is needed for. Do not guess credentials, call the HTTP API directly, or attempt other workarounds.

This skill references operations in HTTP-shorthand form (e.g., GET /, GET /_cat/indices, GET /{index}/_mapping, GET /{index}/_settings/index.mode, POST /_query). The Operations table at the end of this document maps each shorthand to the equivalent elastic CLI command — always use the CLI rather than calling the HTTP API directly.

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Analysis without cluster access

The CLI check above gates querying the cluster — it does not gate analysis. When the user has already supplied the evidence in their question (metric values, counts, status reasons, log lines, alert payloads, configuration), reason from that evidence and deliver the conclusion.

When you genuinely do need data the user has not provided, still say what you would check and how — name the specific query, index, and field that would settle the question — and then ask for CLI setup. An answer that names the check is useful without a cluster; one that only asks for setup is not.

Everything here is expressed in ES|QL (POST /_query) or the Kibana Observability APIs. Do not use Query DSL, and do not use the ES|QL KQL search function — express predicates natively (WHERE service.name == "checkout").

Jobs to be done

  • Answer "is service X healthy?" with a verdict and the evidence behind it

  • Answer "why is service X slow / erroring / quiet?" by localizing the change to the service, a dependency, or its infrastructure

  • Read SLO status, burn rate, and remaining error budget during an incident

  • Determine which alerting rules currently apply to a service, including all-services rules

  • Funnel a noisy log stream down to the failures that explain the degradation

  • Identify which attribute (version, host, pod, region, route) distinguishes the failing or slow subpopulation

  • Distinguish a healthy service from a service with no telemetry

Output discipline

Applies to every response produced under this skill.

  • Commit to the best-supported conclusion. When the evidence points one way, say so. Do not downgrade confidence to sound cautious — hedging on unambiguous evidence is a defect, not humility.

  • Commit to a verdict: healthy, degraded, or unhealthy, followed by the reason. A triage answer that does not name one of the three has not done the job.

  • State confidence once, in the conclusion. Do not restate it per bullet.

  • Do not speculate past the evidence. If the telemetry did not show a cause, it does not go in the answer. Name what is unknown and stop. Never offer a mechanism ("probably a GC pause", "likely a noisy neighbor") that no signal measured.

  • Report absence as absence. Zero rows means the data is missing or not collected; it never means the underlying condition is healthy. "No dependency metrics" is not "dependencies are fine".

  • Do not pad. No restating the question, no narrating which queries were run unless the result mattered, no summarizing the summary.

  • End on the finding. No trailing offers such as "want me to dig deeper?". Actionable follow-ups belong in a recommendations list, phrased as recommendations, not as questions.

Signal hierarchy

Signals disagree constantly. This ordering decides which one wins.

RankSignalAuthority
1SLO status and burn rateAuthoritative when SLOs exist. They encode the agreed definition of "good" for this service
2Active alerting rulesAuthoritative when no SLO covers the symptom. Sourced from the Alerting API
3Error rate, latency, throughputDescribes the degradation. Decisive only when nothing above it exists
4Dependency healthLocates the cause upstream or downstream; does not by itself set the verdict
5ML anomaliesDeviation from learned baseline, not from a target. Corroborates and time-bounds
6Infrastructure (CPU, memory, OOM)Explains a mechanism. A saturated pod with healthy golden signals is a risk, not an outage
7LogsExplain, never decide. Log volume is not health

Conflict rules:

  • SLO healthy, latency elevated → degraded but within error budget. The verdict follows the SLO; report the trend as a risk with the burn rate.

  • SLO violated, current-window metrics look fine → trust the SLO and check its window. SLOs are evaluated over hours or days; a 15-minute ES|QL window can look clean while the budget is already spent.

  • Alerts firing, no SLO defined → the alerts are the verdict. Resolve each rule's params to confirm it actually targets this service before attributing it.

  • Logs noisy, golden signals flat → not degraded. High log volume without an error-rate or latency change is a logging-configuration finding, not a health finding.

  • Throughput collapsed, error rate flat → the caller stopped calling. Look upstream before blaming this service.

  • Any query returns zero rows → missing data. Say which signal is unavailable and lower the scope of the verdict accordingly; never convert silence into health.

Routing: symptom to first signal

Presenting symptomPull firstReference
"Is X healthy?" / unclearSLO status, then active rules, then golden signalsslo-and-alerts.md
"X is slow"Latency percentiles versus the prior period, then dependency latencyapm-signals.md
"X is erroring" / 5xxError rate by route, then failed-transaction correlationapm-signals.md
"X is down" / no trafficThroughput, then confirm the service still ingests at allapm-signals.md
"Only some requests are bad"Subpopulation correlation over candidate attributesapm-signals.md
"An alert fired" / "the SLO is burning"Rule params and SLO burn rate, then the metric the rule watchesslo-and-alerts.md
"What is in the logs?" / noisy logsThe log funnel — iterate with NOT exclusionslog-investigation.md
Suspected OOM, throttling, restartsContainer CPU and memory limit utilizationapm-signals.md
"Is it saturated?" on a non-K8s hostHost CPU, memory, and load average from the hostmetrics receiverapm-signals.md
"Which downstream is hurting X?"Per-destination call volume, latency, and failure rateapm-signals.md

Data sources

OTel-native data streams, verified against Elasticsearch 9.6.0:

DataIndex pattern
Traces (spans, transactions)traces-*.otel-*; classic Elastic APM agent ingest also lands in traces*apm*
Logslogs-*.otel-*
Raw metricsmetrics-*.otel-*; classic APM agent ingest also lands in metrics*apm*
Service inventory (1m rollup)metrics-service_summary.1m.otel-*
Transaction rollups (1m)metrics-service_transaction.1m.otel-*, metrics-transaction.1m.otel-*
Dependency rollups (1m)metrics-service_destination.1m.otel-*
Kubernetesmetrics-kubeletstatsreceiver.otel-*, metrics-k8sclusterreceiver.otel-*, logs-k8seventsreceiver.otel-*
Host (VM, bare metal)metrics-hostmetricsreceiver.otel-*; the Elastic Agent system integration lands in metrics-system.*

service.name is populated on traces, metrics, and logs, so it is the join key across all three. Use flat OTel field paths in ES|QL (k8s.pod.name, not resource.attributes.k8s.pod.name). When analyzing OTel application metrics, the ES|QL TS (time series) command gives more efficient metric queries. It is GA on Serverless; on Stack it is preview in 9.2 and GA in 9.4, so below 9.4 use FROM with BUCKET instead. TS also rejects COUNT(*) — count a field instead.

The recipes in this skill and its references are written against the OTel-native streams above. A service instrumented with the classic Elastic APM agent ships to traces-apm* and metrics-apm* under different field names (transaction.duration.us, event.outcome), so these recipes return no rows for it. An empty result on a service that is otherwise clearly alive is therefore a scope boundary, not evidence of an outage: check which index family the service actually writes (GET /_cat/indices) and report the ingest path rather than concluding from silence.

ES|QL feature availability

Three features this skill uses are newer than its 8.11 base floor. Check GET / before relying on them: build_flavor: "serverless" means all three are available; otherwise compare version.number against the Stack column. Never report "no data" when the real answer is that the query did not run — say which feature was unavailable and use the fallback.

FeatureServerlessStackLicenceUsed byFallback
FORKGApreview 9.1-9.3, GA 9.4+anyThe log funnel, and the subpopulation comparisonRun each branch as a separate query and combine the results yourself
CATEGORIZEGApreview 9.0, GA 9.1PlatinumMessage categorization inside the log funnelGroup by a truncated message prefix, or funnel on structured error fields
TSGApreview 9.2, GA 9.4anyOTel application metric queriesFROM with BUCKET over the same data stream

The Platinum requirement on CATEGORIZE is not a version check. A 9.6 Stack cluster on a Basic or Gold licence fails it exactly as an 8.11 cluster fails FORK, and the error names the licence rather than the syntax. On Serverless the function is GA with no separate licence gate.

Process: triage a degraded service

  1. Fix the service and the window. Resolve the service name and the time range from the request. Use the user's time range — do not silently assume the last hour when the complaint is historical. If no range is given, use the last hour and say so. Confirm the service actually exists in telemetry with a COUNT(*) BY service.name over traces-*.otel-* via POST /_query; if the name does not appear, resolve the ambiguity before querying further.

    Decision: which service and window every later query is scoped to. Data: distinct service.name values in range.

  2. Read SLO status and burn rate. List SLOs with GET kbn:/api/observability/slos and fetch the ones bound to this service with GET kbn:/api/observability/slos/{id}. Read status, current SLI, burn rate, and remaining error budget.

    Decision: does an agreed contract exist, and is it being violated? If yes, the verdict is already determined and the remaining steps only explain it. If no SLO covers this service, say so once and fall through to step 3.

  3. Determine which alerting rules apply to this service, and which of them are firing. Call GET kbn:/api/alerting/rules/_find with per_page=100&filter=alert.attributes.enabled:true, paging with page if total exceeds what you received. Then filter the response client-side. Do not query .alerts* indices to determine active state — the Alerting API response is the source of truth. Fetch a rule's full definition with GET kbn:/api/alerting/rule/{id} when its params are needed.

    Do not narrow this call server-side. The _find filter parameter is KQL over saved-object attributes, and params is not among them — filter=alert.attributes.params.serviceName:<name> returns zero rules on a cluster that has them. Narrowing by search=apm&search_fields=tags, by alertTypeId, or by consumer is worse: it drops rules on a naming convention or a rule-type allowlist, and the rules it drops are disproportionately the all-services ones. See references/slo-and-alerts.md for the measured failure.

    From the fetched set, evaluate both rules whose params.serviceName matches the service and rules where params.serviceName is absent, because the latter are all-services rules that apply to it too. Read execution_status.status on each: active means the rule's last run produced alerts, ok means it ran and produced none, and error means it is not evaluating at all — a blind spot, not a pass.

    Decision: what covers this service, and is any of it currently firing? Data: rule params.serviceName, rule type, and execution status.

  4. Check ML anomalies, if any jobs exist. List jobs with GET /_ml/anomaly_detectors and confirm they are running with GET /_ml/anomaly_detectors/_stats — a stopped job produces no anomalies, which is not the same as no anomaly. Pull scored records with GET /_ml/anomaly_detectors/{id}/results/records.

    Decision: did latency, throughput, or error rate deviate from its learned baseline, and when? Use the anomaly window to narrow steps 5 and 6.

  5. Measure the golden signals. Run ES|QL over traces-*.otel-* for throughput, latency (avg, p95, p99), and error rate, bucketed over the window and compared against the immediately preceding window of equal length. See references/apm-signals.md.

    Decision: is the service actually changed relative to itself, and in which dimension? Data: request count, latency percentiles, and failure ratio for the current and prior windows.

  6. Localize: dependencies, then subpopulation, then infrastructure.

    • Dependencies — aggregate metrics-service_destination.1m.otel-* by span.destination.service.resource for call volume, average latency, and failure rate. If this query returns zero rows for the service, the service is not APM-instrumented for dependencies; report insufficient dependency data and do not claim upstreams are healthy.

    • Subpopulation — when only part of the traffic is bad, compare the failure or slow rate per candidate attribute against the overall rate to find which attribute is over-represented. See references/apm-signals.md.

    • Infrastructure — read the resource attributes on the service's spans (k8s.pod.name, container.id, host.name) first, then branch on what they contain. Pod and namespace attributes mean the service is Kubernetes-hosted: check k8s.container.cpu_limit_utilization and k8s.container.memory_limit_utilization in metrics-kubeletstatsreceiver.otel-*. A host.name with no pod attributes means the service runs on a VM or bare host, where every k8s.* field is empty: check system.cpu.utilization, system.memory.utilization, and system.cpu.load_average.1m in metrics-hostmetricsreceiver.otel-* instead. OOM kills, CPU throttling, and host saturation degrade APM health directly. See references/apm-signals.md.

    • Recent change — a deploy is the most common cause of a step change. Search deploy annotations for the service with GET kbn:/api/apm/services/{serviceName}/annotation/search over the incident window, and compare the failure or latency rate by service.version in the subpopulation query. An annotation inside the onset window is a strong correlation; confirm it plausibly explains the symptom before attributing.

    Decision: is the cause inside this service, in something it calls, in one slice of its instances, under it, or in a change that landed?

    When the Kubernetes branch shows saturation, restarts, or an OOM kill, the mechanism is established and the remaining diagnosis — why the pod is being killed, whether the node is under pressure, whether a rollout is stuck — belongs to the observability-k8s-investigation skill. Hand off rather than continuing here.

  7. Explain with logs. Scope logs by service.name, or by trace.id when a specific failing trace is in hand, and run the funnel until the remaining set is small enough to read. See references/log-investigation.md. Logs confirm and articulate the cause; they do not overturn steps 2 and 3.

  8. State the verdict. Healthy, degraded, or unhealthy, with the reason and one statement of confidence, followed by recommendations. Name any signal that was unavailable.

Examples

"Is checkout healthy?" — resolve the window, read its SLOs, then the active rules including all-services rules, then throughput, latency percentiles, and error rate over traces-*.otel-* against the prior window. If the availability SLO is at 99.2% against a 99.5% target with a burn rate above 1, the verdict is unhealthy on SLO violation, and the golden signals are the explanation, not the verdict.

"Why is the frontend slow?" — compare p95 and p99 for the current window against the previous window of equal length. If service-level latency rose while per-destination latency in metrics-service_destination.1m.otel-* is flat, the added time is inside the service; if one destination's average response time rose in step with it, the dependency is the cause and the frontend is a victim.

"Only some checkout requests fail" — run the subpopulation comparison: failure rate grouped by service.version, k8s.pod.name, host.name, and cloud.region alongside the overall failure rate. An attribute value whose failure rate is several times the overall rate, on a volume large enough to matter, is the correlated attribute. On live data, grouping frontend server spans by route showed a 3.8% slow rate for POST against a 0.9% overall rate — a 4x lift that localizes the problem to write paths.

"The cart service logs look bad" — run the funnel over logs-*.otel-* scoped to service.name == "cart": get trend, total, samples, and message categorization in one FORK, then add NOT ... LIKE exclusions for each dominant pattern and re-run with the full accumulated filter until fewer than 20 patterns remain. High log volume alone is not a health verdict — check the golden signals before calling the service degraded.

"Is the payment service's upstream healthy?" — query metrics-service_destination.1m.otel-* for it. Zero rows means the service does not emit dependency metrics. Report that dependency data is unavailable for this service and give the verdict from the signals that do exist; do not report the upstreams as healthy.

"An alert fired on api-gateway" — fetch the enabled rules with no server-side narrowing, then match in memory on params.serviceName == "api-gateway" and on rules with no params.serviceName, reading execution_status.status to see which are firing. Read the firing rule's threshold from GET kbn:/api/alerting/rule/{id}, then query the same metric over the same window in ES|QL to confirm the rule is describing a real change rather than a threshold that is set too tight.

Guidelines

  • Work the signal hierarchy in order and stop when the evidence supports a verdict. Do not run every query in this document on every request.

  • Anchor to SLO status and burn rate when SLOs exist. When they do not, fall back to alerts, ML anomalies, throughput, latency, error rate, dependencies, infrastructure, and logs — and say that no SLO covers the service.

  • Use the Alerting API for active-alert state. Never query .alerts* indices for it. Always evaluate both service-scoped rules and rules with no params.serviceName.

  • Fetch alerting rules unnarrowed and filter client-side. _find cannot filter on params, tag search drops rules that do not follow a naming convention, and executionStatus.status:active returns only rules that are firing right now — each of those silently hides the all-services rules the bullet above requires.

  • Always use the user's time range. Compare every metric against the immediately preceding window of equal length — absolute numbers without a baseline do not support a verdict.

  • Zero rows is missing data. Say which signal is unavailable rather than treating silence as a pass.

  • Scope every query by service.name and a bounded @timestamp range, and cap output with LIMIT. Prefer coarse buckets when only a trend is needed.

  • Prefer event.outcome == "failure" for failed spans; status.code == "Error" is equivalent on OTel traces but is null on successes, so it cannot be counted directly.

  • Filter server-side traffic with kind == "Server" when measuring a service's own throughput and latency, so client spans do not double-count.

  • Treat log.level and severity_text as hints, never as filters you rely on. On real OTel data most log records carry no level at all and those that do disagree on case and vocabulary (INFO, Information, SEVERE, Normal). In particular never write log.level == "error" — the lowercase ECS vocabulary is not what the OTel SDKs emit, so it returns zero rows with no error even on a service that is logging errors, and reports the service healthy. Use the normalized numeric severity_number >= 17 if you need a severity predicate at all.

  • Logs explain; they do not decide. Never issue a verdict whose only support is log content.

  • Do not invent field names. If a field might not exist in this deployment, confirm the data stream exists with GET /_resolve/index/{pattern} before building on it.

  • Establish where the service runs before checking saturation. Kubernetes and host telemetry share no field names, so a Kubernetes query against a VM-hosted service returns zero rows and says nothing about whether it is saturated.

  • Pass --drop-null-columns on POST /_query when a result is mostly empty columns. Infrastructure metrics are sparse by nature — limit utilization is absent wherever no limit is declared — and the flag collapses the noise while listing the suppressed column names under all_columns, so nothing is hidden.

Operations

HTTP API (shorthand)elastic CLI command
GET /elastic es info
POST /_queryelastic es esql query --format tsv --query '<esql>'
GET /_resolve/index/{pattern}elastic es indices resolve-index --name '<pattern>'
GET /_ml/anomaly_detectorselastic es ml get-jobs
GET /_ml/anomaly_detectors/_statselastic es ml get-job-stats
GET /_ml/anomaly_detectors/{id}/results/recordselastic es ml get-records --job-id '<id>'
GET kbn:/api/observability/sloselastic kb slo find-slos-op --space-id '<space>' --kql-query '<kql>'
GET kbn:/api/observability/slos/{id}elastic kb slo get-slo-op --space-id '<space>' --slo-id '<id>'
GET kbn:/api/alerting/rules/_findelastic kb alerting get-alerting-rules-find --filter '<filter>'
GET kbn:/api/alerting/rule/{id}elastic kb alerting get-alerting-rule-id --id '<id>'
GET kbn:/api/apm/services/{serviceName}/annotation/searchelastic kb apm-annotations get-annotation --service-name '<service>' --environment '<env>' --start '<iso8601>' --end '<iso8601>'

The SLO find command takes a KQL query string because that is the API's contract; it is not an exception to the ES|QL rule for data queries.

The annotation search route rejects a request that omits environment, so pass ENVIRONMENT_ALL when the service's environment is not known. Only the search direction is in scope: this skill is read-only, so the companion create-annotation operation is deliberately not bound.

Files

references/apm-signals.md

APM Signals

ES|QL patterns for the trace- and metric-derived signals used in triage: throughput, latency, error rate, dependency health, subpopulation correlation, ML anomalies, and infrastructure saturation. Every query here was executed against Elasticsearch 9.6.0 with live OpenTelemetry data. Run them with POST /_query.

Scoping rules

  • Filter by service.name and a bounded @timestamp range on every query.

  • Add kind == "Server" when measuring a service's own throughput and latency. Without it, client spans emitted by the same service are counted as inbound traffic and both the rate and the percentiles are wrong.

  • duration on OTel spans is in nanoseconds. Divide by 1000000.0 for milliseconds.

  • Prefer event.outcome == "failure" to identify failed spans. status.code == "Error" marks the same spans but is null on successful ones, so aggregating it requires a CASE.

  • Cap every query with LIMIT. Choose a bucket size that yields roughly 20-50 buckets over the window.

Throughput, latency, and error rate over time

FROM traces-*.otel-*
| WHERE service.name == "frontend" AND kind == "Server"
  AND @timestamp >= NOW() - 1 hour
| STATS requests = COUNT(*),
        failures = COUNT(*) WHERE event.outcome == "failure",
        p95_ms = ROUND(PERCENTILE(duration, 95) / 1000000.0, 2)
    BY bucket = BUCKET(@timestamp, 5 minute)
| EVAL error_rate = ROUND(COALESCE(failures, 0)::double / requests, 4)
| SORT bucket DESC
| LIMIT 500

COALESCE matters: COUNT(*) WHERE ... returns null, not 0, when nothing matches, and a null error rate reads as missing data rather than as zero failures.

Current window against the prior window

A single window of absolute numbers does not support a verdict. Split one query into two comparable windows:

FROM traces-*.otel-*
| WHERE service.name == "frontend" AND kind == "Server"
  AND @timestamp >= NOW() - 2 hours
| EVAL window = CASE(@timestamp >= NOW() - 1 hour, "current", "previous")
| STATS requests = COUNT(*),
        avg_ms = ROUND(AVG(duration) / 1000000.0, 2),
        p95_ms = ROUND(PERCENTILE(duration, 95) / 1000000.0, 2),
        p99_ms = ROUND(PERCENTILE(duration, 99) / 1000000.0, 2),
        failures = COUNT(*) WHERE event.outcome == "failure"
    BY window
| EVAL error_rate = ROUND(COALESCE(failures, 0)::double / requests, 4)
| KEEP window, requests, avg_ms, p95_ms, p99_ms, error_rate

Reading it:

  • p99 up, p50/avg flat — a tail problem. A subset of requests is affected; go to subpopulation correlation.

  • All percentiles up together — a whole-service change: a deploy, a saturated resource, or a slow dependency on the hot path.

  • Requests down sharply, error rate flat — the callers stopped calling. The change is upstream, not here.

  • Requests up and latency up — load-driven. Check saturation before blaming code.

Error rate by route

Localize errors to a route before going deeper:

FROM traces-*.otel-*
| WHERE service.name == "checkout" AND kind == "Server"
  AND @timestamp >= NOW() - 1 hour
| STATS requests = COUNT(*),
        failures = COUNT(*) WHERE event.outcome == "failure"
    BY span.name
| EVAL error_rate = ROUND(COALESCE(failures, 0)::double / requests, 4)
| WHERE requests >= 20
| SORT error_rate DESC
| LIMIT 20

transaction.name is available on transaction documents and is often coarser (for example the HTTP method); span.name carries the operation. Group by whichever is populated for the service at hand.

Dependency health

Downstream call volume, latency, and failure rate come from the 1-minute dependency rollup:

FROM metrics-service_destination.1m.otel-*
| WHERE service.name == "frontend" AND @timestamp >= NOW() - 1 hour
| STATS calls = SUM(span.destination.service.response_time.count),
        total_us = SUM(span.destination.service.response_time.sum.us),
        failed = SUM(span.destination.service.response_time.count) WHERE event.outcome == "failure"
    BY span.destination.service.resource
| EVAL avg_ms = ROUND(total_us / calls / 1000.0, 2),
       failure_rate = ROUND(COALESCE(failed, 0)::double / calls, 4)
| KEEP span.destination.service.resource, calls, avg_ms, failure_rate
| SORT calls DESC
| LIMIT 20

Zero rows is a finding, not a pass. A service with no rows in metrics-service_destination.1m.otel-* is not APM-instrumented for dependencies. Report insufficient dependency data and give the verdict from the signals that do exist. Never translate an empty dependency result into "upstreams are healthy".

For a service-map-style view of which services call which, aggregate the destination rollup across services:

FROM metrics-service_destination.1m.otel-*
| WHERE @timestamp >= NOW() - 1 hour
| STATS calls = SUM(span.destination.service.response_time.count)
    BY service.name, span.destination.service.resource
| SORT calls DESC
| LIMIT 50

Subpopulation correlation

Replaces the correlations technique that previously required a bespoke script. When only part of the traffic is slow or failing, the question is: which attribute value is over-represented in the affected set relative to the population as a whole?

Compute the overall rate and the per-attribute rate in one query, using FORK so both come back from a single call. FORK is GA on Serverless; on Stack it is preview in 9.1-9.3 and GA from 9.4, and it does not parse below 9.1. Where it is unavailable, run the two branches as two queries and compute the lift yourself — FORK saves a round trip here, nothing more:

FROM traces-*.otel-*
| WHERE service.name == "frontend" AND kind == "Server"
  AND @timestamp >= NOW() - 3 hours
| EVAL affected = CASE(duration > 100000000, 1, 0)
| FORK (STATS total = COUNT(*), affected = SUM(affected) | EVAL scope = "overall", attribute_value = "*")
       (STATS total = COUNT(*), affected = SUM(affected) BY attribute_value = transaction.name | EVAL scope = "by-attribute")
| EVAL rate = ROUND(affected::double / total, 4)
| KEEP scope, attribute_value, total, affected, rate
| SORT rate DESC
| LIMIT 20

The SORT and LIMIT here apply to both branches combined, so on a service with more than twenty distinct transaction.name values the overall row competes with the per-attribute rows and can be pushed out of the result — leaving you the subpopulations with no baseline to compare them against. Raise the LIMIT above the expected cardinality, or read the baseline from the separate error-rate query instead. This is the same combined-limit behaviour that silently drops whole branches in the log funnel; it is worth knowing wherever FORK is followed by a limit.

Swap the affected expression for the symptom under investigation:

  • Failures: EVAL affected = CASE(event.outcome == "failure", 1, 0)

  • Slow requests: EVAL affected = CASE(duration > 100000000, 1, 0) — duration is the field Elastic writes on OTel-native spans, in nanoseconds (the value above is 100 ms; OpenTelemetry itself carries only start and end timestamps). The APM-compatibility fields span.duration.us and transaction.duration.us are microseconds. Pick the threshold from the p95 of the healthy window, not from a round number, and convert before reporting: a 3 000 000 000 ns span is three seconds, not three thousand.

Repeat the query once per candidate attribute, changing only the BY attribute_value = ... clause. Columns with the same name must have the same type in every FORK branch, and the overall branch fixes attribute_value as a keyword with "*" — so cast any key that is not a keyword, or the query is rejected with conflicting data types in FORK branches: BY attribute_value = http.response.status_code::string. Candidates worth testing, in the order they usually pay off:

service.version · k8s.pod.name · host.name · k8s.deployment.name · container.id · cloud.region · cloud.availability_zone · service.environment · span.name · transaction.name · http.response.status_code::string · then the service's own request-scoped attributes — whatever the application sets on its spans (a SKU, tenant, plan, customer tier, feature flag), usually under attributes.*. A fault keyed on one of those is invisible to every infrastructure attribute above.

What makes an attribute correlated

An attribute value is correlated when all three hold:

  1. Lift. Its rate is meaningfully higher than the overall rate — roughly 2x or more. Small differences on a busy service are noise.

  2. Volume. It has enough events to be stable. Discard groups below about 20 events; a single failure out of three requests is a 33% rate and means nothing.

  3. Concentration. It accounts for a substantial share of the total affected events. An attribute with a 90% failure rate that explains 4 of 500 failures is a curiosity, not the cause. Measure the share on the service that sets the attribute: one slow request produces one slow span per hop, so across several services a request-scoped attribute appears to cover a fraction of the affected spans while covering all of them on the service where it originates.

An attribute that shows high lift and covers most of the affected events is the localization. On live data, frontend server spans grouped by route gave a 3.8% slow rate for POST against a 0.9% overall rate — a 4x lift covering half the slow requests, which localizes the problem to write paths.

Two traps:

  • Cardinality artifacts. Attributes near-unique per request (trace ID, user ID, session ID) always look correlated. Only test attributes shared by many events.

  • Proxy attributes. If a single pod is running the only instance of a bad version, k8s.pod.name and service.version both light up. Prefer the explanation with a mechanism — a version rollout beats a pod name — and check whether the attribute values move together.

When no attribute shows lift, the degradation is uniform across the population. That is itself a result: report that the problem is service-wide and look at dependencies or infrastructure instead of hunting for a slice — but only after the service's own request-scoped attributes have been tested. No lift on route, status, instance and version says the split is not by where the request ran; on live data a fault confined to one product SKU showed a flat 4–9% slow rate against 6% overall on every infrastructure attribute and 100% on the SKU attribute.

ML anomalies

Anomaly detection describes deviation from a learned baseline, not from a target, so it corroborates and time-bounds a finding rather than setting the verdict.

  1. GET /_ml/anomaly_detectors — find jobs whose configuration references the service.

  2. GET /_ml/anomaly_detectors/_stats — confirm the job state is opened and the datafeed is running. A stopped job produces no records, which is not the same as no anomaly. Report the job as unavailable in that case.

  3. GET /_ml/anomaly_detectors/{id}/results/records — read scored records. Treat record_score at or above 75 as significant, 50-75 as worth corroborating, below 50 as background.

Use the anomaly's start time to narrow the trace and log windows in the rest of the triage.

Infrastructure saturation

Read the resource attributes off the service's own spans first, so infrastructure is scoped to the instances actually serving traffic:

FROM traces-*.otel-*
| WHERE service.name == "cart" AND @timestamp >= NOW() - 1 hour
| STATS spans = COUNT(*) BY k8s.pod.name, k8s.namespace.name, host.name
| SORT spans DESC
| LIMIT 20

That result decides which branch to take, and the branch matters because the two paths share no field names. Pod and namespace attributes mean the service is Kubernetes-hosted and the kubeletstats fields apply. A populated host.name with no pod attributes means the service runs on a VM or a bare host, where every k8s.* field is empty — read the host metrics instead. Do not conclude that a service is unsaturated because the Kubernetes query returned nothing.

Kubernetes-hosted services

Check limit utilization per container for the pods that serve the traffic:

FROM metrics-kubeletstatsreceiver.otel-*
| WHERE @timestamp >= NOW() - 1 hour AND k8s.namespace.name == "otel-demo"
| STATS cpu_limit_pct = ROUND(MAX(k8s.container.cpu_limit_utilization) * 100, 1),
        mem_limit_pct = ROUND(MAX(k8s.container.memory_limit_utilization) * 100, 1)
    BY k8s.pod.name, k8s.container.name
| SORT mem_limit_pct DESC
| LIMIT 20

Memory limit utilization approaching 100% precedes OOM kills; sustained CPU limit utilization at 100% means throttling, which shows up in APM as latency without any error-rate change. Container restarts and OOM events are also visible in logs-k8seventsreceiver.otel-* when the Kubernetes events receiver is deployed — absence of that data stream means the receiver is not installed, not that no restarts happened.

The container-level fields are the measure to use, and the pod-level pair k8s.pod.cpu_limit_utilization / k8s.pod.memory_limit_utilization is not a substitute for them. See Container-level against pod-level limit utilization below for what separates them and why the container fields are the default. observability-k8s-investigation applies the same rule.

k8s.container.cpu_limit_utilization and k8s.container.memory_limit_utilization are only populated when the container declares the corresponding limit. A null result means no limit is set, not that the container is idle.

These two fields fail in two different ways, and only one of them returns null. Where the receiver emits the metric, an undeclared limit gives null per the paragraph above. Where the metric is not enabled at all, the field is absent from the mapping and the query above fails with HTTP 400 Unknown column rather than returning null. On a Stack 9.4.4 cluster k8s.container.memory_limit_utilization was absent from metrics-kubeletstatsreceiver.otel-* entirely while k8s.container.cpu_limit_utilization was present, so the query above returned Unknown column [k8s.container.memory_limit_utilization], did you mean [k8s.container.cpu_limit_utilization]? — and both fields were present on a Serverless comparator, so this is a collector-configuration difference rather than a flavour one. Run GET /_field_caps on the two field names before building the query, and drop whichever is unmapped rather than reading the error as missing data.

Two fall-backs, in order of preference:

  • k8s.pod.cpu.node.utilization and k8s.pod.memory.node.utilization express consumption as a fraction of node capacity and are emitted regardless of whether limits are declared. They answer "is this pod a heavy tenant of its node?" rather than "is this pod at its own ceiling." Both were populated on the Stack cluster above and returned sensible values where the container-level fields were unusable.

  • container.cpu.usage and container.memory.usage give absolute consumption, which is only interpretable against a baseline for the same workload. container.memory.usage is itself absent on some collector builds — the Stack cluster above carried container.memory.working_set instead — so confirm which of the two exists before using it.

Both fall-backs sit on the pod-level documents, not the container-level ones, so query them grouped by k8s.pod.name rather than by k8s.container.name.

Saturation is the mechanism, not the verdict. When the finding is a restart loop, an OOM kill to confirm, node pressure, an admission failure, or a stuck rollout, stop here and hand off to the observability-k8s-investigation skill, which owns workload, node, and control-plane diagnosis.

Container-level against pod-level limit utilization

Both field families exist in the kubeletstats receiver and they are not interchangeable. The receiver emits them on separate documents in the same data stream: pod-level fields appear on documents that carry no k8s.container.name, and container-level fields appear only on documents that do. A STATS ... BY k8s.container.name therefore returns null for every pod-level field, and the reverse holds too. Measured over one hour on a live 9.6.0 cluster: of 42,240 documents without a container name, 360 carried k8s.pod.cpu_limit_utilization and none carried k8s.container.cpu_limit_utilization; of 18,240 documents with a container name, 900 carried the container field and none carried the pod field.

Availability differs as well. Container-level utilization is emitted for each container that declares the limit, while the pod-level aggregate requires every container in the pod to declare it. Across two live clusters over three hours, no pod carried the pod-level field without also carrying the container-level one, while 27 pods carried the container-level field with the pod-level field absent — every one of them a multi-container pod in which only some containers declared limits.

ClusterContainer level onlyBoth levelsNeitherPod level only
forge-factory (Serverless)187440
k8s-demo (Serverless)96400
Stack 9.4.4, CPU03190
Stack 9.4.4, memory00184

The "pod level only: 0" column does not generalize. On the Stack cluster the container-level memory field was not mapped at all, so four pods carried pod-level memory limit utilization with no container-level counterpart — the case both Serverless clusters showed zero of. Where the container-level field exists it remains the right default, because a limit is enforced per container and the container form is emitted per container that declares one. But "available strictly more often" is a property of those two Serverless deployments, not a rule: check which of the two families is mapped before choosing, and be prepared for the pod-level field to be the only one available. Use the pod-level fields when the question really is about the pod as a whole — total pod consumption against the sum of its containers' limits — or when the container-level field is absent, and in either case say which level the number came from.

Host-based services

For a service on a VM or bare host with the OTel hostmetrics receiver collecting, saturation comes from metrics-hostmetricsreceiver.otel-*. CPU utilization there is reported per state, so busy CPU is derived from the idle state rather than read directly:

FROM metrics-hostmetricsreceiver.otel-*
| WHERE host.name == "prod-app-01" AND @timestamp >= NOW() - 1 hour
| STATS cpu_idle = AVG(system.cpu.utilization) WHERE state == "idle",
        mem_used_pct = ROUND(MAX(system.memory.utilization) * 100, 1) WHERE state == "used",
        load_1m = ROUND(MAX(`system.cpu.load_average.1m`), 2),
        cores = MAX(system.cpu.logical.count)
    BY host.name
| EVAL cpu_busy_pct = ROUND((1 - cpu_idle) * 100, 1)
| KEEP host.name, cpu_busy_pct, mem_used_pct, load_1m, cores
| SORT cpu_busy_pct DESC
| LIMIT 20

Two syntax points that cause silent wrong answers. system.cpu.utilization and system.memory.utilization are both broken out by a state dimension, so an unfiltered AVG averages across idle, user, system, wait, and steal and means nothing. And system.cpu.load_average.1m needs backticks in ES|QL, because the 1m segment starts with a digit; without them the query fails to parse.

This query is executed and confirmed on Stack 9.4.4: it returned cpu_busy_pct 4.4, mem_used_pct 22.2, load_1m 1.4 and cores 8 for a live host, so the 1 - idle derivation, the per-aggregate WHERE inside STATS, and the backticked load-average field all behave as written on Stack.

Reading it: a host has no enforced ceiling the way a container does, so the pressure signal is cpu_busy_pct near 100 sustained, load_1m above cores, or mem_used_pct high enough that the kernel is reclaiming. Load average above core count with moderate busy CPU means processes are queueing on something other than CPU — usually disk or a lock.

For a full disk, system.filesystem.utilization lives in the same data stream only when the collector's filesystem scraper is enabled, which is not the default in every distribution. On the Stack 9.4.4 cluster above, _field_caps for system.filesystem.* over metrics-hostmetricsreceiver.otel-* returned nothing at all while every system.cpu.*, system.memory.*, system.disk.* and system.network.* field was present — so naming it fails the query with Unknown column rather than returning no rows. Where it is absent, system.disk.io_time and system.disk.pending_operations are usually collected and answer the I/O-saturation question, though not the capacity one.

When the host is monitored by the Elastic Agent system integration rather than the hostmetrics receiver, the equivalents are system.cpu.total.norm.pct in metrics-system.cpu-* and system.memory.actual.used.pct in metrics-system.memory-*. Both are already normalized fractions of capacity, so the 1 - idle derivation is not needed. These two names remain documentation-derived: the Stack cluster used to validate the rest of this file had no System integration installed — GET /_resolve/index/metrics-system.* returned zero indices and zero data streams, and both field names were absent from _field_caps across all of metrics-* — so they have not been executed against data. Note also that the two collection paths do not share field names, so a query written for one returns Unknown column against the other rather than empty results. Confirm which path exists with GET /_resolve/index/metrics-system.*,metrics-hostmetricsreceiver.* before building on either.

Aggregate rollups

metrics-service_summary.1m.otel-* is the cheapest way to enumerate which services reported telemetry in a window, which distinguishes "healthy" from "not reporting":

FROM metrics-service_summary.1m.otel-*
| WHERE @timestamp >= NOW() - 1 hour
| STATS docs = COUNT(*) BY service.name
| SORT docs DESC
| LIMIT 50

metrics-service_transaction.1m.otel-* and metrics-transaction.1m.otel-* hold pre-aggregated transaction latency as histogram and summary fields (transaction.duration.histogram, transaction.duration.summary). They are cheaper than raw spans over long windows; raw traces-*.otel-* remains the right source when the investigation needs per-request attributes for correlation.

For OTel application metrics, the TS (time series) command produces more efficient queries than FROM. It is GA on Serverless; on Stack it is preview in 9.2 and GA in 9.4, so on anything below 9.4 use FROM with BUCKET over the same data stream. TS also rejects COUNT(*) — count a specific field instead.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs Node.js

The author says: Requires the `elastic` CLI (>= 0.2) with Elasticsearch and Kibana contexts on the same cluster. Base floor is Elasticsearch 8.11+ or Serverless. Three ES|QL features need more, each with a fallback at its point of use: `FORK` (Stack GA 9.4), `CATEGORIZE` (Stack GA 9.1, Platinum licence) and `TS` (Stack GA 9.4); all are GA on Serverless. Reads APM/OTel traces, metrics and logs, the Kibana SLO and Alerting APIs, and the Elasticsearch ML APIs. Read-only.

Security

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Attribution and licence

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elastic/agent-skills · skills/observability/sre-triage · commit 09d879d
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  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
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