sentry_log.go

package indexer

import (
	"errors"
	"io"

	"github.com/ethereum/go-ethereum/log"
	"github.com/getsentry/sentry-go"
)

var jsonFmt = log.JSONFormat()

// SentryStreamHandler creates a log.Handler that behaves similarly to
// log.StreamHandler, however it writes any log with severity greater than or
// equal to log.LvlError to Sentry. In that case, the passed log.Record is
// encoded using JSON rather than the default terminal output, so that it can be
// captured for debugging in the Sentry dashboard.
func SentryStreamHandler(wr io.Writer, fmtr log.Format) log.Handler {
	h := log.FuncHandler(func(r *log.Record) error {
		_, err := wr.Write(fmtr.Format(r))
		// If this record's severity is log.LvlError or higher,
		// serialize the record using JSON and write it to Sentry. We
		// also capture the error message separately so that it's easy
		// to parse what the error is in the dashboard.
		//
		// NOTE: The log.Lvl* constants are defined in reverse order of
		// their severity, i.e. zero (log.LvlCrit) is the highest
		// severity.
		if r.Lvl <= log.LvlError {
			sentry.WithScope(func(scope *sentry.Scope) {
				scope.SetExtra("context", jsonFmt.Format(r))
				sentry.CaptureException(errors.New(r.Msg))
			})
		}
		return err
	})
	return log.LazyHandler(log.SyncHandler(h))
}