Invalid character 'm' looking for beginning of value

[bgins]

While investigating our error handling, I uncovered an issue reporting HTTPErrors in response to posts to the solver.

Our HTTPError is defined here:

lilypad/pkg/http/utils.go

Lines 41 to 44 in d30b6d8

	type HTTPError struct {
	Message string
	StatusCode int
	}

It's a wrapper around an error message that let's us add a status code.

When handling a POST, a handler may return an HTTPError or a plain error:

lilypad/pkg/http/utils.go

Lines 246 to 257 in d30b6d8

	data, err := handler(requestBody, res, req)
	if err != nil {
	log.Error().
	Str("method POST", req.URL.String()).
	Err(err).
	Msgf("")
	httpError, ok := err.(HTTPError)
	if ok {
	http.Error(res, httpError.Error(), httpError.StatusCode)
	} else {
	http.Error(res, err.Error(), http.StatusInternalServerError)
	}

When using an HTTPError, we take the provided status code or otherwise report a 500 http.StatusInternalServerError status code.

The set up for triggering this error is a bit contrived, but likely reveals an underlying issue where we will fail to correctly report errors.

Start the chain and solver. Comment out the line of code where we add a user header in our clients:

lilypad/pkg/http/utils.go

Line 106 in d30b6d8

req.Header.Add(X_LILYPAD_USER_HEADER, userPayload)

Start a resource provider. It should immediately fail with this error:

Error: invalid character 'm' looking for beginning of value

We handle this error when we check for the user header in the solver:

lilypad/pkg/http/utils.go

Lines 118 to 124 in d30b6d8

	userHeader := req.Header.Get(X_LILYPAD_USER_HEADER)
	if userHeader == "" {
	return "", HTTPError{
	Message: "missing user header",
	StatusCode: http.StatusUnauthorized,
	}
	}

Stop the solver. Change the status code in the user header check to http.StatusInternalServerError.

Run the resource provider again and it will not fail with the invalid character error. Instead, it will retry attempts to contact the solver and eventually fail when the max retries are reached.

You may also want to reduce the number of retries to speed up the process:

lilypad/pkg/http/utils.go

Line 415 in d30b6d8

retryClient.RetryMax = 10