Add a function for querying remote Alertmanager version

alertmanager/version.go

@@ -0,0 +1,50 @@
+package alertmanager
+
+import (
+	"github.com/cloudflare/unsee/config"
+	"github.com/cloudflare/unsee/transport"
+
+	log "github.com/Sirupsen/logrus"
+)
+
+// AlertmanagerVersion is what api/v1/status returns, we only use it to check
+// version, so we skip all other keys (except for status)
+type alertmanagerVersion struct {
+	Status string `json:"status"`
+	Data   struct {
+		VersionInfo struct {
+			Version string `json:"version"`
+		} `json:"versionInfo"`
+	} `json:"data"`
+}
+
+// GetVersion returns version information of the remote Alertmanager endpoint
+func GetVersion() string {
+	// if everything fails assume Alertmanager is at latest possible version
+	defaultVersion := "999.0.0"
+
+	url, err := transport.JoinURL(config.Config.AlertmanagerURI, "api/v1/status")
+	if err != nil {
+		log.Errorf("Failed to join url '%s' and path 'api/v1/status': %s", config.Config.AlertmanagerURI, err.Error())
+		return defaultVersion
+	}
+	ver := alertmanagerVersion{}
+	err = transport.GetJSONFromURL(url, config.Config.AlertmanagerTimeout, &ver)
+	if err != nil {
+		log.Errorf("%s request failed: %s", url, err.Error())
+		return defaultVersion
+	}
+
+	if ver.Status != "success" {
+		log.Errorf("Request to %s returned status %s", url, ver.Status)
+		return defaultVersion
+	}
+
+	if ver.Data.VersionInfo.Version == "" {
+		log.Error("No version information in Alertmanager API")
+		return defaultVersion
+	}
+
+	log.Infof("Remote Alertmanager version: %s", ver.Data.VersionInfo.Version)
+	return ver.Data.VersionInfo.Version
+}