Add alwaysDisplayed option to datasource plugins, this will allow it to show up…

Add alwaysDisplayed option to datasource plugins, this will allow it to show up as an option to select when adding queries to a panel without actually adding it as a datasource.

pkg/api/frontendsettings.go

@@ -102,18 +102,14 @@ func getFrontendSettingsMap(c *middleware.Context) (map[string]interface{}, erro
 		datasources[ds.Name] = dsMap
 	}
 
-	// add grafana backend data source
-	grafanaDatasourceMeta, _ := plugins.DataSources["grafana"]
-	datasources["-- Grafana --"] = map[string]interface{}{
-		"type": "grafana",
-		"name": "-- Grafana --",
-		"meta": grafanaDatasourceMeta,
-	}
-
-	// add mixed backend data source
-	datasources["-- Mixed --"] = map[string]interface{}{
-		"type": "mixed",
-		"meta": plugins.DataSources["mixed"],
+	for _, ds := range plugins.DataSources {
+		if ds.AlwaysDisplay {
+			datasources[ds.Name] = map[string]interface{}{
+				"type": ds.Type,
+				"name": ds.Name,
+				"meta": plugins.DataSources[ds.Id],
+			}
+		}
 	}
 
 	if defaultDatasource == "" {

pkg/plugins/datasource_plugin.go

@@ -4,12 +4,13 @@ import "encoding/json"
 
 type DataSourcePlugin struct {
 	FrontendPluginBase
-	Annotations bool   `json:"annotations"`
-	Metrics     bool   `json:"metrics"`
-	Alerting    bool   `json:"alerting"`
-	BuiltIn     bool   `json:"builtIn"`
-	Mixed       bool   `json:"mixed"`
-	App         string `json:"app"`
+	Annotations   bool   `json:"annotations"`
+	Metrics       bool   `json:"metrics"`
+	Alerting      bool   `json:"alerting"`
+	BuiltIn       bool   `json:"builtIn"`
+	Mixed         bool   `json:"mixed"`
+	AlwaysDisplay bool   `json:"alwaysDisplay"`
+	App           string `json:"app"`
 }
 
 func (p *DataSourcePlugin) Load(decoder *json.Decoder, pluginDir string) error {

public/app/plugins/datasource/grafana/plugin.json

 {
   "type": "datasource",
-  "name": "Grafana",
+  "name": "-- Grafana --",
   "id": "grafana",
 
   "builtIn": true,
   "annotations": true,
+  "alwaysDisplay": true,
   "metrics": true
 }

public/app/plugins/datasource/mixed/plugin.json

 {
   "type": "datasource",
-  "name": "Mixed datasource",
+  "name": "-- Mixed --",
   "id": "mixed",
 
   "builtIn": true,
   "mixed": true,
+  "alwaysDisplay": true,
   "metrics": true
 }