add initial version of Grafana updater

grafana-watcher/updater/updater.go

@@ -0,0 +1,86 @@
+package updater
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/coreos/kube-prometheus/grafana-watcher/grafana"
+)
+
+type Updater interface {
+	OnModify() error
+}
+
+type GrafanaDashboardUpdater struct {
+	client grafana.DashboardsInterface
+	glob   string
+}
+
+func NewGrafanaDashboardUpdater(c grafana.DashboardsInterface, g string) Updater {
+	return &GrafanaDashboardUpdater{
+		client: c,
+		glob:   g,
+	}
+}
+
+func (u *GrafanaDashboardUpdater) OnModify() error {
+	err := u.deleteAllDashboards()
+	if err != nil {
+		return err
+	}
+	err = u.createDashboardsFromFiles()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (u *GrafanaDashboardUpdater) deleteAllDashboards() error {
+	log.Println("Retrieving existing dashboards")
+	searchResults, err := u.client.Search()
+	if err != nil {
+		return err
+	}
+
+	log.Printf("Deleting %d dashboards\n", len(searchResults))
+	for _, d := range searchResults {
+		log.Println("Deleting dashboard:", d.Slug())
+
+		err := u.client.Delete(d.Slug())
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (u *GrafanaDashboardUpdater) createDashboardsFromFiles() error {
+	filePaths, err := filepath.Glob(u.glob)
+	if err != nil {
+		return err
+	}
+
+	for _, fp := range filePaths {
+		u.createDashboardFromFile(fp)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (u *GrafanaDashboardUpdater) createDashboardFromFile(filePath string) error {
+	log.Println("Creating dashboard from:", filePath)
+
+	f, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return u.client.Create(f)
+}