dsproxy: move http client variable back

After refactoring to be able to mock the client in
a test, the client wasn't a global variable anymore.
This change moves the client back to being a package-
level variable.

pkg/api/pluginproxy/ds_proxy.go

@@ -27,6 +27,7 @@ import (
 var (
 	logger     = log.New("data-proxy-log")
 	tokenCache = map[string]*jwtToken{}
+	client     = newHTTPClient()
 )
 
 type jwtToken struct {
@@ -36,16 +37,15 @@ type jwtToken struct {
 }
 
 type DataSourceProxy struct {
-	ds         *m.DataSource
-	ctx        *m.ReqContext
-	targetUrl  *url.URL
-	proxyPath  string
-	route      *plugins.AppPluginRoute
-	plugin     *plugins.DataSourcePlugin
-	httpClient HttpClient
+	ds        *m.DataSource
+	ctx       *m.ReqContext
+	targetUrl *url.URL
+	proxyPath string
+	route     *plugins.AppPluginRoute
+	plugin    *plugins.DataSourcePlugin
 }
 
-type HttpClient interface {
+type httpClient interface {
 	Do(req *http.Request) (*http.Response, error)
 }
 
@@ -58,10 +58,13 @@ func NewDataSourceProxy(ds *m.DataSource, plugin *plugins.DataSourcePlugin, ctx
 		ctx:       ctx,
 		proxyPath: proxyPath,
 		targetUrl: targetURL,
-		httpClient: &http.Client{
-			Timeout:   time.Second * 30,
-			Transport: &http.Transport{Proxy: http.ProxyFromEnvironment},
-		},
+	}
+}
+
+func newHTTPClient() httpClient {
+	return &http.Client{
+		Timeout:   time.Second * 30,
+		Transport: &http.Transport{Proxy: http.ProxyFromEnvironment},
 	}
 }
 
@@ -341,7 +344,7 @@ func (proxy *DataSourceProxy) getAccessToken(data templateData) (string, error)
 	getTokenReq.Header.Add("Content-Type", "application/x-www-form-urlencoded")
 	getTokenReq.Header.Add("Content-Length", strconv.Itoa(len(params.Encode())))
 
-	resp, err := proxy.httpClient.Do(getTokenReq)
+	resp, err := client.Do(getTokenReq)
 	if err != nil {
 		return "", err
 	}

pkg/api/pluginproxy/ds_proxy_test.go

@@ -165,7 +165,8 @@ func TestDSRouteRule(t *testing.T) {
 					json, err := ioutil.ReadFile("./test-data/access-token-1.json")
 					So(err, ShouldBeNil)
 
-					proxy1 := NewDataSourceProxyWithMock(ds, plugin, ctx, "pathwithtoken1", json)
+					client = newFakeHTTPClient(json)
+					proxy1 := NewDataSourceProxy(ds, plugin, ctx, "pathwithtoken1")
 					proxy1.route = plugin.Routes[0]
 					proxy1.applyRoute(req)
 
@@ -178,7 +179,8 @@ func TestDSRouteRule(t *testing.T) {
 						So(err, ShouldBeNil)
 
 						req, _ := http.NewRequest("GET", "http://localhost/asd", nil)
-						proxy2 := NewDataSourceProxyWithMock(ds, plugin, ctx, "pathwithtoken2", json2)
+						client = newFakeHTTPClient(json2)
+						proxy2 := NewDataSourceProxy(ds, plugin, ctx, "pathwithtoken2")
 						proxy2.route = plugin.Routes[1]
 						proxy2.applyRoute(req)
 
@@ -192,7 +194,8 @@ func TestDSRouteRule(t *testing.T) {
 						Convey("third call to first route should add cached access token", func() {
 							req, _ := http.NewRequest("GET", "http://localhost/asd", nil)
 
-							proxy3 := NewDataSourceProxyWithMock(ds, plugin, ctx, "pathwithtoken1", []byte{})
+							client = newFakeHTTPClient([]byte{})
+							proxy3 := NewDataSourceProxy(ds, plugin, ctx, "pathwithtoken1")
 							proxy3.route = plugin.Routes[0]
 							proxy3.applyRoute(req)
 
@@ -322,11 +325,11 @@ func TestDSRouteRule(t *testing.T) {
 	})
 }
 
-type HttpClientStub struct {
+type httpClientStub struct {
 	fakeBody []byte
 }
 
-func (c *HttpClientStub) Do(req *http.Request) (*http.Response, error) {
+func (c *httpClientStub) Do(req *http.Request) (*http.Response, error) {
 	bodyJSON, _ := simplejson.NewJson(c.fakeBody)
 	_, passedTokenCacheTest := bodyJSON.CheckGet("expires_on")
 	So(passedTokenCacheTest, ShouldBeTrue)
@@ -340,17 +343,8 @@ func (c *HttpClientStub) Do(req *http.Request) (*http.Response, error) {
 	return resp, nil
 }
 
-func NewDataSourceProxyWithMock(ds *m.DataSource, plugin *plugins.DataSourcePlugin, ctx *m.ReqContext, proxyPath string, fakeBody []byte) *DataSourceProxy {
-	targetURL, _ := url.Parse(ds.Url)
-
-	return &DataSourceProxy{
-		ds:        ds,
-		plugin:    plugin,
-		ctx:       ctx,
-		proxyPath: proxyPath,
-		targetUrl: targetURL,
-		httpClient: &HttpClientStub{
-			fakeBody: fakeBody,
-		},
+func newFakeHTTPClient(fakeBody []byte) httpClient {
+	return &httpClientStub{
+		fakeBody: fakeBody,
 	}
 }