Plugins Proxy: Allow using {{ .URL }} inside "routes" section in plugin.json (#80858)

Signed-off-by: Slach <bloodjazman@gmail.com>
Co-authored-by: Andres Martinez Gotor <andres.mgotor@gmail.com>

pkg/api/pluginproxy/ds_proxy_test.go

@@ -158,6 +158,36 @@ func TestDataSourceProxy_routeRule(t *testing.T) {
 			assert.Equal(t, "http://localhost/asd", req.URL.String())
 		})
 
+		t.Run("When matching route path and has setting url", func(t *testing.T) {
+			ctx, req := setUp()
+			proxy, err := setupDSProxyTest(t, ctx, ds, routes, "api/common/some/method")
+			require.NoError(t, err)
+			proxy.matchedRoute = &plugins.Route{
+				Path: "api/common",
+				URL:  "{{.URL}}",
+				Headers: []plugins.Header{
+					{Name: "x-header", Content: "my secret {{.SecureJsonData.key}}"},
+				},
+				URLParams: []plugins.URLParam{
+					{Name: "{{.JsonData.queryParam}}", Content: "{{.SecureJsonData.key}}"},
+				},
+			}
+
+			dsInfo := DSInfo{
+				ID:       ds.ID,
+				Updated:  ds.Updated,
+				JSONData: jd,
+				DecryptedSecureJSONData: map[string]string{
+					"key": "123",
+				},
+				URL: "https://dynamic.grafana.com",
+			}
+			ApplyRoute(proxy.ctx.Req.Context(), req, proxy.proxyPath, proxy.matchedRoute, dsInfo, proxy.cfg)
+
+			assert.Equal(t, "https://dynamic.grafana.com/some/method?apiKey=123", req.URL.String())
+			assert.Equal(t, "my secret 123", req.Header.Get("x-header"))
+		})
+
 		t.Run("When matching route path and has dynamic body", func(t *testing.T) {
 			ctx, req := setUp()
 			proxy, err := setupDSProxyTest(t, ctx, ds, routes, "api/body")