Using the tracing middleware

[klaus-nji-vi]

Do we have additional literature on the tracing functionality? I see the request ID middleware which extracts the request-id from an X-Request-ID header. My questions regarding usage of this library include:

1. What if the X-Request-ID header is not present, does the middleware create a new one?
2. If the request ID needs to be propagated beyond the bounds of a specific service, how should this be done?
3. How does the library enable exporting of the trace to sinks such as Amazon X-ray, Elasticsearch etc?

[aldas]

Best source would be to check what that middleware does - Request ID middleware is very small so there should not be a problem to understand what is going on

echo/middleware/request_id.go

Lines 61 to 70 in 63c62bc

	rid := req.Header.Get(config.TargetHeader)
	if rid == "" {
	rid = config.Generator()
	}
	res.Header().Set(config.TargetHeader, rid)
	if config.RequestIDHandler != nil {
	config.RequestIDHandler(c, rid)
	}
	return next(c)

So if header we are targeting does not exists in header middleware will generate new value for it and set it for response (res) header.
Configuration object allows you to add custom function that is executed with that extracted ID and current request context - this allows you do set that id to context, add additional headers or whatever you need.