Logging API Traffic Without Storing Secrets

Useful API logs should explain what happened without preserving everything that crossed the network. Start with a narrow goal: identify failed requests, measure latency, and follow retries without recording credentials or private conversations. The walkthrough below builds a small, testable logging policy rather than relying on developers to remember what to remove.

Choose the request details you actually need

1. Write down the questions your logs must answer. Did the request succeed? How long did it take? Which operation failed? Then define an allowlist: the exact fields your logger may accept. OpenTelemetry recommends data minimization and notes that its tooling cannot automatically determine what is sensitive in your application. ([opentelemetry.io](https://opentelemetry.io/docs/security/handling-sensitive-data/))

• Record a timestamp, an application-generated request identifier, the HTTP method, and a normalized route name.
• Record the response status, elapsed time, retry count, and a controlled error category.
• Include a validated model identifier or token counts only when they serve a defined operational purpose.

For example, design a completion event to say that request req_demo_42 returned status 429 after 800 milliseconds. It should not need the authorization header or prompt to tell that story.

Exclude credentials and conversation content by default

2. Configure your logger to omit authorization headers, API keys, cookies, passwords, and session tokens. OWASP identifies access tokens, authentication passwords, and encryption keys among the data that should not be recorded directly. For this workflow, remove them rather than storing an encrypted copy in the log. ([cheatsheetseries.owasp.org](https://cheatsheetseries.owasp.org/cheatsheets/Logging_Cheat_Sheet.html?utm_source=openai))

Keep request and response bodies disabled by default. Apply that rule to prompts, generated text, tool arguments, and uploaded documents. Use synthetic content when debugging payload structure, rather than temporarily enabling production body capture.

Build safe events before calling the logger

3. Create one logging helper that constructs a new event from approved fields. Do not pass the original request object into it. Validate field types, limit string lengths, and reject unexpected attributes. OpenTelemetry documents attribute deletion and allowlist-based redaction as ways to reduce sensitive telemetry. ([opentelemetry.io](https://opentelemetry.io/docs/security/handling-sensitive-data/))

For your first implementation, make the helper accept only the fields selected in step one. Prefer a route template over an unrestricted URL, and a controlled error category over an arbitrary message. Treat collector-side redaction as a second layer, not permission to send raw secrets into the telemetry pipeline. OpenTelemetry provides collector processors for scrubbing sensitive attributes. ([opentelemetry.io](https://opentelemetry.io/docs/security/config-best-practices/))

Check failures and every intermediate logging layer

4. Inspect exception handlers, SDK debug settings, reverse proxies, tracing integrations, and terminal output. OWASP specifically warns that verbose logging and exception objects can expose request bodies or credentials, including through third-party monitoring integrations. ([owasp.github.io](https://owasp.github.io/www-project-web-security-testing-guide/latest/4-Web_Application_Security_Testing/02-Configuration_and_Deployment_Management/02-Application_Platform_Configuration?utm_source=openai))

Map failures to categories such as authentication_failed, rate_limited, timeout, or upstream_error. For streaming requests, plan one completion event containing duration and outcome instead of logging individual content chunks. Keep retries connected with your application-generated request identifier.

Test secret exclusion with recognizable fake values

5. Send test requests containing unmistakable dummy secrets in headers, query parameters, nested objects, and error-producing inputs. Search every configured destination for those markers, including local output and exported telemetry. Make their absence an automated test requirement.

Repeat the test for unsuccessful requests and logging-system failures. OWASP recommends testing logging mechanisms, checking field definitions, and verifying behavior when logging encounters problems. Never use a real credential as your test marker. ([cheatsheetseries.owasp.org](https://cheatsheetseries.owasp.org/cheatsheets/Logging_Cheat_Sheet.html?utm_source=openai))

Apply the same policy when using a relay

6. If a pay-as-you-go desk for multiple model families fits your application, consider Relay365. Keep the same application-side logging helper around relay calls. Before sending sensitive workloads, review the relay's current retention and data-handling terms; excluding content from your logs does not establish what another service stores. Create a Relay365 account if that workflow suits your needs, and begin with synthetic requests.

Restrict log access and schedule deletion

7. Give log access only to people who need it, protect transmission and storage, and define retention periods for logs and their copies. OWASP recommends restricted access and disposal that accounts for applicable retention obligations. Finish by assigning an owner to review the logging policy whenever integrations change. ([cheatsheetseries.owasp.org](https://cheatsheetseries.owasp.org/cheatsheets/Logging_Cheat_Sheet.html?utm_source=openai))