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Custom Error Handling with Sentry in Fiber v3

This recipe demonstrates production-ready error handling and monitoring patterns in Fiber v3 integrated with Sentry:

  1. Per-Request Sentry Hub: Leverages official github.com/gofiber/contrib/v3/sentry middleware to clone a dedicated Sentry Hub for each request with deep-copied request data. The user ID comes from the client-supplied X-User-ID header and is not authenticated; in a real app, take it from your auth middleware instead.
  2. Selective Error Reporting: Custom fiber.ErrorHandler captures internal server errors (status >= 500) to Sentry while avoiding alert noise from expected client errors (4xx, such as validation failures or 404s). For 5xx responses the client only gets the generic status text; the error details stay in Sentry.
  3. Panic Recovery: Catches unexpected runtime panics, forwards the fatal stack trace to Sentry, and returns a graceful 500 JSON response to the client.
  4. Sentry Event ID Correlation: Injects the Sentry event_id into error responses so clients can reference specific incident IDs in support inquiries or logs.

Project Structure​

.
├── go.mod
├── go.sum
├── main.go
├── main_test.go
└── README.md

Running the Recipe​

Set your SENTRY_DSN environment variable and run:

export SENTRY_DSN="https://[email protected]/project-id"
go run main.go

The application starts on port :3000. On Ctrl+C (or SIGTERM) it shuts down gracefully and flushes pending Sentry events before exiting.

1. Normal Request (200 OK)​

curl -i http://localhost:3000/

Returns:

{"message":"Fiber with Sentry Error Handling","status":"ok"}

2. Client-Side Error (400 Bad Request)​

Expected client errors return clean JSON without triggering Sentry issues:

curl -i http://localhost:3000/users/invalid

Returns HTTP 400:

{"error":"invalid user id provided","status":400}

3. Server-Side Error (500 Internal Server Error)​

Unhandled internal exceptions are captured in Sentry with the full error message, while the client gets a generic message and the event_id:

curl -i -H "X-User-ID: user-42" http://localhost:3000/error

Returns HTTP 500:

{
  "error": "Internal Server Error",
  "event_id": "4b6840742f104d49a239be9b6b797b5e",
  "status": 500
}

4. Runtime Panic Recovery​

Unexpected panics are caught by SentryRecover(), reported with stack traces to Sentry, and resolved safely:

curl -i -H "X-User-ID: user-admin" http://localhost:3000/panic

Returns HTTP 500:

{
  "error": "Internal Server Error",
  "event_id": "9a1f28b4929841f2bb0da93510e19034",
  "status": 500
}

Running Tests​

Run the unit test suite (utilizing Sentry's in-memory mock transport):

go test -v ./...