Add structured logging for HTTP server errors

proxy/log.go

@@ -0,0 +1,21 @@
+package proxy
+
+import (
+	stdlog "log"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	// HTTP server type identifiers for logging
+	logtagFieldHTTPServer = "http-server"
+	logtagValueHTTPS      = "https"
+	logtagValueACME       = "acme"
+	logtagValueDebug      = "debug"
+)
+
+// newHTTPServerLogger creates a standard library logger that writes to logrus
+// with the specified server type field.
+func newHTTPServerLogger(logger *log.Logger, serverType string) *stdlog.Logger {
+	return stdlog.New(logger.WithField(logtagFieldHTTPServer, serverType).WriterLevel(log.WarnLevel), "", 0)
+}