CDN Traffic Anomaly Diagnosis

Diagnose CDN traffic/bandwidth anomalies: "traffic suddenly increased", "bandwidth spiked last night", "CDN bill jumped, suspect traffic theft", "is someone hotlinking my resources", "locate the abnormal time window".

Core approach: confirm identity and target domain, pull bps/flow/QPS usage data for the requested time window, compute a baseline (mean/median), locate anomalous intervals by peak/baseline comparison, then run offline-log forensics on the anomalous window (four-dimension Top statistics, 13 theft-abuse rules, T1~T6 scenario classification) and output a structured conclusion with evidence-based suggestions.

Absolute Rules

1. ABSOLUTE PROHIBITION (read-only enforcement): Under NO circumstances may you generate, write, or execute any command/script calling a mutating API — e.g. StopCdnDomain, DeleteCdnDomain, SetDomainServerCertificate, Modify*, RefreshObjectCaches, PushObjectCache, or any configuration change. This includes scripts "for the user to run manually". If the user asks to stop a domain, block hotlinkers, or change configuration, only output the manual remediation workflow and declare this skill is read-only.
2. ABSOLUTE PROHIBITION (credential handling): Never read, print, or pass AK/SK/STS tokens explicitly. Credentials are resolved automatically by the aliyun CLI default credential chain. Never accept AK/SK from the user or from another script.
3. NO FABRICATION: Every conclusion must be grounded in data actually returned by the usage-data APIs. If a query fails or returns empty, record it and state the limitation — never invent traffic numbers.
4. EXECUTION RULE FOR ERRORS: On any API error, log [WARN] <Code>: <Message> to stderr and continue with the remaining queries — never silently skip or abort the whole diagnosis. The final report is still produced with the data at hand. Exception — critical domain/account-level errors (InvalidDomain.NotFound, InvalidAccessKeyId.NotFound, CdnServiceNotFound): every remaining query for the same target would fail identically, so the script short-circuits them (fail fast — one failed call instead of a full failed sweep) and reports the first critical error with its actionable guidance.

Observability

All OpenAPI calls (invoked through the aliyun CLI) include:

• User-Agent: --user-agent AlibabaCloud-Agent-Skills/{SKILL_NAME}/{session-id}/skill-version/{skill-version} (skill-version resolves from the SKILL_VERSION env var, else references/manifest.json)
• SKILL_NAME: alibabacloud-cdn-traffic-anomaly
• session-id: 32-character hex string generated per diagnostic session (one uuid.uuid4().hex per script run) and attached to every CLI command in the same run.