Fix watch error when http & https are disabled (#3493)

Remove an error in watch reloading that happens when http and https
are both disabled, and use an https address for running watches if
no http addresses are present.

Fixes #3425.

agent/agent.go

@@ -515,8 +515,19 @@ func (a *Agent) serveHTTP(l net.Listener, srv *HTTPServer) error {
 // reloadWatches stops any existing watch plans and attempts to load the given
 // set of watches.
 func (a *Agent) reloadWatches(cfg *config.RuntimeConfig) error {
+	// Stop the current watches.
+	for _, wp := range a.watchPlans {
+		wp.Stop()
+	}
+	a.watchPlans = nil
+
+	// Return if there are no watches now.
+	if len(cfg.Watches) == 0 {
+		return nil
+	}
+
 	// Watches use the API to talk to this agent, so that must be enabled.
-	if len(cfg.HTTPAddrs) == 0 {
+	if len(cfg.HTTPAddrs) == 0 && len(cfg.HTTPSAddrs) == 0 {
 		return fmt.Errorf("watch plans require an HTTP or HTTPS endpoint")
 	}
 
@@ -539,15 +550,15 @@ func (a *Agent) reloadWatches(cfg *config.RuntimeConfig) error {
 		watchPlans = append(watchPlans, wp)
 	}
 
-	// Stop the current watches.
-	for _, wp := range a.watchPlans {
-		wp.Stop()
+	// Determine the primary http(s) endpoint.
+	var netaddr net.Addr
+	if len(cfg.HTTPAddrs) > 0 {
+		netaddr = cfg.HTTPAddrs[0]
+	} else {
+		netaddr = cfg.HTTPSAddrs[0]
 	}
-	a.watchPlans = nil
-
-	// deterine the primary http endpoint
-	addr := cfg.HTTPAddrs[0].String()
-	if cfg.HTTPAddrs[0].Network() == "unix" {
+	addr := netaddr.String()
+	if netaddr.Network() == "unix" {
 		addr = "unix://" + addr
 	}
 

agent/agent_test.go

@@ -1918,3 +1918,49 @@ func TestAgent_GetCoordinate(t *testing.T) {
 	check(true)
 	check(false)
 }
+
+func TestAgent_reloadWatches(t *testing.T) {
+	t.Parallel()
+	a := NewTestAgent(t.Name(), "")
+	defer a.Shutdown()
+
+	// Normal watch with http addr set, should succeed
+	newConf := *a.config
+	newConf.Watches = []map[string]interface{}{
+		{
+			"type":    "key",
+			"key":     "asdf",
+			"handler": "ls",
+		},
+	}
+	if err := a.reloadWatches(&newConf); err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+
+	// Should still succeed with only HTTPS addresses
+	newConf.HTTPSAddrs = newConf.HTTPAddrs
+	newConf.HTTPAddrs = make([]net.Addr, 0)
+	newConf.Watches = []map[string]interface{}{
+		{
+			"type":    "key",
+			"key":     "asdf",
+			"handler": "ls",
+		},
+	}
+	if err := a.reloadWatches(&newConf); err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+
+	// Should fail to reload with no http or https addrs
+	newConf.HTTPSAddrs = make([]net.Addr, 0)
+	newConf.Watches = []map[string]interface{}{
+		{
+			"type":    "key",
+			"key":     "asdf",
+			"handler": "ls",
+		},
+	}
+	if err := a.reloadWatches(&newConf); err == nil || !strings.Contains(err.Error(), "watch plans require an HTTP or HTTPS endpoint") {
+		t.Fatalf("bad: %s", err)
+	}
+}