TRACE_EXPORTER=gofr logs TRACER_URL credentials unredacted on every failed span export #4495

Summary

With TRACE_EXPORTER=gofr, every failed span export logs the raw TRACER_URL, including credentials in its userinfo or query string. The startup log line and the OTel error handler already redact the URL, but the gofr exporter's own export-failure log does not.

Since TRACER_HEADERS is documented as unsupported for the gofr exporter, credentials in the URL are the only way to authenticate it.

Reproduction

A test in package gofr:

• an httptest collector returns 401;
• TRACE_EXPORTER=gofr, TRACER_URL=http://bob:S3CRETPASS@127.0.0.1:<port>/api/spans?api_key=TOPSECRETKEY;
• the test ends one span, then flushes traces.

ERROR failed to post spans on 'http://bob:S3CRETPASS@127.0.0.1:63676/api/spans?api_key=TOPSECRETKEY', unexpected response status code: '401'
ERROR failed to post spans on 'http://REDACTED@127.0.0.1:63676/api/spans?REDACTED', unexpected response status code: '401'

The first line comes from the exporter itself. The second is the same error logged again by the OTel error handler, redacted.

Root cause

pkg/gofr/exporter.go (processSpans, around lines 83-99) builds failed to post spans on '%v' from e.endpoint and logs it through its own logger without redaction. The client.Do error is also logged raw, and it can contain the URL as well.

Suggested fix

• Use exporters.RedactURL(e.endpoint) in the message, and exporters.RedactMessage on the client.Do error.
• Or drop the exporter's own log line, since the returned error is already logged (redacted) by the OTel error handler.
• Add a test asserting the secret does not appear in the logs.