Cluster C2: API Debugging
Common API auth header mistakes
Authentication failures often look like backend bugs but start at the request edge: malformed Authorization headers, missing prefixes, stale signatures, or token strings encoded with the wrong strategy. This page gives a practical way to isolate header-level issues before escalating to service owners.
High-frequency failure patterns
- Bearer token sent without the
Bearerprefix. - Whitespace or line breaks introduced while copying secrets from dashboards.
- Timestamp skew in signed requests causing immediate signature invalidation.
- Header key casing mismatch in custom gateway or proxy transformations.
- Double-encoding query or body values used in HMAC canonical strings.
Debug checklist before escalation
- Capture raw outgoing request headers from client or edge logs.
- Verify token structure and expiration manually before replaying requests.
- Rebuild the request with a deterministic tool so hidden mutations are visible.
- Compare canonical payload, timestamp, nonce, and signature inputs one-by-one.
- Only escalate after you can reproduce the failure with minimal deterministic inputs.
Team-level prevention controls
Add preflight checks in local tooling and CI for token format, header presence, and signing prerequisites. Keep one trusted request fixture per auth scheme and run it whenever client SDK or gateway config changes. In incident playbooks, require responders to capture both raw request and canonical signing inputs so root cause analysis is fast and reproducible.
Practical input/output example
Validate the Authorization header structure before escalating token issues.
Input
Authorization: eyJhbGciOiJIUzI1NiJ9...
Output
Authorization: Bearer eyJhbGciOiJIUzI1NiJ9...