Allow setting a timeout for request handling

This is a high-level timeout for the http.Handler application code,
not a low-level network timeout.

serverutil/http.go

@@ -26,6 +26,7 @@ var gracefulShutdownTimeout = 3 * time.Second
 type ServerConfig struct {
 	TLS                 *TLSServerConfig `yaml:"tls"`
 	MaxInflightRequests int              `yaml:"max_inflight_requests"`
+	RequestTimeoutSecs  int              `yaml:"request_timeout"`
 	TrustedForwarders   []string         `yaml:"trusted_forwarders"`
 }
 
@@ -60,11 +61,18 @@ func (config *ServerConfig) buildHTTPServer(h http.Handler) (*http.Server, error
 		}
 	}
 
+	// Wrap the handler with a TimeoutHandler if 'request_timeout'
+	// is set.
+	h = addDefaultHandlers(h)
+	if config.RequestTimeoutSecs > 0 {
+		h = http.TimeoutHandler(h, time.Duration(config.RequestTimeoutSecs)*time.Second, "")
+	}
+
 	// These are not meant to be external-facing servers, so we
 	// can be generous with the timeouts to keep the number of
 	// reconnections low.
 	return &http.Server{
-		Handler:      defaultHandler(h),
+		Handler:      h,
 		ReadTimeout:  30 * time.Second,
 		WriteTimeout: 30 * time.Second,
 		IdleTimeout:  600 * time.Second,
@@ -134,7 +142,7 @@ func Serve(h http.Handler, config *ServerConfig, addr string) error {
 	return nil
 }
 
-func defaultHandler(h http.Handler) http.Handler {
+func addDefaultHandlers(h http.Handler) http.Handler {
 	root := http.NewServeMux()
 
 	// Add an endpoint for HTTP health checking probes.