code that verifies the Docker daemon connection before adding

controller/node.go

@@ -58,19 +58,19 @@ func PostNode(c *gin.Context) {
 	node.CA = in.CA
 	node.Arch = "linux_amd64"
 
+	err = engine.Allocate(node)
+	if err != nil {
+		c.String(http.StatusBadRequest, err.Error())
+		return
+	}
+
 	err = model.InsertNode(db, node)
 	if err != nil {
 		c.AbortWithStatus(http.StatusInternalServerError)
 		return
 	}
 
-	ok := engine.Allocate(node)
-	if !ok {
-		c.AbortWithStatus(http.StatusInternalServerError)
-	} else {
-		c.IndentedJSON(http.StatusOK, node)
-	}
-
+	c.IndentedJSON(http.StatusOK, node)
 }
 
 func DeleteNode(c *gin.Context) {

engine/engine.go

@@ -26,7 +26,7 @@ type Engine interface {
 	Cancel(int64, int64, *model.Node) error
 	Stream(int64, int64, *model.Node) (io.ReadCloser, error)
 	Deallocate(*model.Node)
-	Allocate(*model.Node) bool
+	Allocate(*model.Node) error
 	Subscribe(chan *Event)
 	Unsubscribe(chan *Event)
 }
@@ -124,9 +124,23 @@ func (e *engine) Unsubscribe(c chan *Event) {
 	e.bus.unsubscribe(c)
 }
 
-func (e *engine) Allocate(node *model.Node) bool {
-	log.Infof("registered docker daemon %s", node.Addr)
-	return e.pool.allocate(node)
+func (e *engine) Allocate(node *model.Node) error {
+
+	// run the full build!
+	client, err := newDockerClient(node.Addr, node.Cert, node.Key, node.CA)
+	if err != nil {
+		log.Errorf("error creating docker client %s. %s.", node.Addr, err)
+		return err
+	}
+	version, err := client.Version()
+	if err != nil {
+		log.Errorf("error connecting to docker daemon %s. %s.", node.Addr, err)
+		return err
+	}
+
+	log.Infof("registered docker daemon %s running version %s", node.Addr, version.Version)
+	e.pool.allocate(node)
+	return nil
 }
 
 func (e *engine) Deallocate(n *model.Node) {

static/styles_gen/style.css

@@ -423,7 +423,7 @@ body.login div.alert { position: fixed; top: 0px; left: 0px; right: 0px; line-he
 
 .tt-open { position: absolute; top: 34px; left: 0px; z-index: 100; display: none; background: #FFF; min-width: 100%; border: 1px solid #eee; border-radius: 0px; }
 
-.tt-selectable:hover, .tt-cursor { background: #f4f4f4; }
+.tt-selectable:hover, .tt-cursor { background: #eff1f5; }
 
 .tt-selectable { padding: 1rem 0.75rem; cursor: pointer; display: flex; }