add global datasource proxy timeout setting

closes grafana#5699

pkg/api/pluginproxy/ds_proxy.go

@@ -54,7 +54,7 @@ func NewDataSourceProxy(ds *m.DataSource, plugin *plugins.DataSourcePlugin, ctx
 
 func newHTTPClient() httpClient {
 	return &http.Client{
-		Timeout:   time.Second * 30,
+		Timeout:   time.Duration(setting.DataProxyTimeout) * time.Second,
 		Transport: &http.Transport{Proxy: http.ProxyFromEnvironment},
 	}
 }

pkg/setting/setting.go

@@ -77,6 +77,7 @@ var (
 	SocketPath         string
 	RouterLogging      bool
 	DataProxyLogging   bool
+	DataProxyTimeout   int
 	StaticRootPath     string
 	EnableGzip         bool
 	EnforceDomain      bool
@@ -583,6 +584,7 @@ func (cfg *Cfg) Load(args *CommandLineArgs) error {
 	// read data proxy settings
 	dataproxy := iniFile.Section("dataproxy")
 	DataProxyLogging = dataproxy.Key("logging").MustBool(false)
+	DataProxyTimeout = dataproxy.Key("timeout").MustInt(30)
 
 	// read security settings
 	security := iniFile.Section("security")