Chore: Refactor Prometheus custom query parameters middleware (#34814)

Following #34473 refactor to use url.ParseQuery in the Prometheus 
custom query parameter middleware.

Ref #34473

pkg/tsdb/prometheus/custom_query_params_middleware.go

@@ -1,12 +1,11 @@
 package prometheus
 
 import (
-	"fmt"
 	"net/http"
 	"net/url"
-	"strings"
 
 	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana/pkg/infra/log"
 )
 
 const (
@@ -14,7 +13,7 @@ const (
 	customQueryParametersKey            = "customQueryParameters"
 )
 
-func customQueryParametersMiddleware() sdkhttpclient.Middleware {
+func customQueryParametersMiddleware(logger log.Logger) sdkhttpclient.Middleware {
 	return sdkhttpclient.NamedMiddlewareFunc(customQueryParametersMiddlewareName, func(opts sdkhttpclient.Options, next http.RoundTripper) http.RoundTripper {
 		customQueryParamsVal, exists := opts.CustomOptions[customQueryParametersKey]
 		if !exists {
@@ -25,22 +24,20 @@ func customQueryParametersMiddleware() sdkhttpclient.Middleware {
 			return next
 		}
 
+		values, err := url.ParseQuery(customQueryParams)
+		if err != nil {
+			logger.Error("Failed to parse custom query parameters, skipping middleware", "error", err)
+			return next
+		}
+
 		return sdkhttpclient.RoundTripperFunc(func(req *http.Request) (*http.Response, error) {
-			params := url.Values{}
-			for _, param := range strings.Split(customQueryParams, "&") {
-				parts := strings.Split(param, "=")
-				if len(parts) == 1 {
-					// This is probably a mistake on the users part in defining the params but we don't want to crash.
-					params.Add(parts[0], "")
-				} else {
-					params.Add(parts[0], parts[1])
+			q := req.URL.Query()
+			for k, keyValues := range values {
+				for _, value := range keyValues {
+					q.Add(k, value)
 				}
 			}
-			if req.URL.RawQuery != "" {
-				req.URL.RawQuery = fmt.Sprintf("%s&%s", req.URL.RawQuery, params.Encode())
-			} else {
-				req.URL.RawQuery = params.Encode()
-			}
+			req.URL.RawQuery = q.Encode()
 
 			return next.RoundTrip(req)
 		})

pkg/tsdb/prometheus/custom_query_params_middleware_test.go

@@ -2,9 +2,12 @@ package prometheus
 
 import (
 	"net/http"
+	"net/url"
+	"strings"
 	"testing"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/stretchr/testify/require"
 )
 
@@ -16,7 +19,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("Without custom query parameters set should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware()
+		mw := customQueryParametersMiddleware(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{}, finalRoundTripper)
 		require.NotNil(t, rt)
 		middlewareName, ok := mw.(httpclient.MiddlewareName)
@@ -36,7 +39,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("Without custom query parameters set as string should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware()
+		mw := customQueryParametersMiddleware(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				customQueryParametersKey: 64,
@@ -60,7 +63,7 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 	})
 
 	t.Run("With custom query parameters set as empty string should not apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware()
+		mw := customQueryParametersMiddleware(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				customQueryParametersKey: "",
@@ -83,8 +86,32 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 		require.Equal(t, "http://test.com/query?hello=name", req.URL.String())
 	})
 
-	t.Run("With custom query parameters set as string should apply middleware", func(t *testing.T) {
-		mw := customQueryParametersMiddleware()
+	t.Run("With custom query parameters set as invalid query string should not apply middleware", func(t *testing.T) {
+		mw := customQueryParametersMiddleware(log.New("test"))
+		rt := mw.CreateMiddleware(httpclient.Options{
+			CustomOptions: map[string]interface{}{
+				customQueryParametersKey: "custom=%%abc&test=abc",
+			},
+		}, finalRoundTripper)
+		require.NotNil(t, rt)
+		middlewareName, ok := mw.(httpclient.MiddlewareName)
+		require.True(t, ok)
+		require.Equal(t, customQueryParametersMiddlewareName, middlewareName.MiddlewareName())
+
+		req, err := http.NewRequest(http.MethodGet, "http://test.com/query?hello=name", nil)
+		require.NoError(t, err)
+		res, err := rt.RoundTrip(req)
+		require.NoError(t, err)
+		require.NotNil(t, res)
+		if res.Body != nil {
+			require.NoError(t, res.Body.Close())
+		}
+
+		require.Equal(t, "http://test.com/query?hello=name", req.URL.String())
+	})
+
+	t.Run("With custom query parameters set should apply middleware for request URL containing query parameters ", func(t *testing.T) {
+		mw := customQueryParametersMiddleware(log.New("test"))
 		rt := mw.CreateMiddleware(httpclient.Options{
 			CustomOptions: map[string]interface{}{
 				customQueryParametersKey: "custom=par/am&second=f oo",
@@ -104,6 +131,36 @@ func TestCustomQueryParametersMiddleware(t *testing.T) {
 			require.NoError(t, res.Body.Close())
 		}
 
-		require.Equal(t, "http://test.com/query?hello=name&custom=par%2Fam&second=f+oo", req.URL.String())
+		require.True(t, strings.HasPrefix(req.URL.String(), "http://test.com/query?"))
+
+		q := req.URL.Query()
+		require.Len(t, q, 3)
+		require.Equal(t, "name", url.QueryEscape(q.Get("hello")))
+		require.Equal(t, "par%2Fam", url.QueryEscape(q.Get("custom")))
+		require.Equal(t, "f+oo", url.QueryEscape(q.Get("second")))
+	})
+
+	t.Run("With custom query parameters set should apply middleware for request URL not containing query parameters", func(t *testing.T) {
+		mw := customQueryParametersMiddleware(log.New("test"))
+		rt := mw.CreateMiddleware(httpclient.Options{
+			CustomOptions: map[string]interface{}{
+				customQueryParametersKey: "custom=par/am&second=f oo",
+			},
+		}, finalRoundTripper)
+		require.NotNil(t, rt)
+		middlewareName, ok := mw.(httpclient.MiddlewareName)
+		require.True(t, ok)
+		require.Equal(t, customQueryParametersMiddlewareName, middlewareName.MiddlewareName())
+
+		req, err := http.NewRequest(http.MethodGet, "http://test.com/query", nil)
+		require.NoError(t, err)
+		res, err := rt.RoundTrip(req)
+		require.NoError(t, err)
+		require.NotNil(t, res)
+		if res.Body != nil {
+			require.NoError(t, res.Body.Close())
+		}
+
+		require.Equal(t, "http://test.com/query?custom=par%2Fam&second=f+oo", req.URL.String())
 	})
 }

pkg/tsdb/prometheus/prometheus.go

@@ -37,7 +37,7 @@ type PrometheusExecutor struct {
 //nolint: staticcheck // plugins.DataPlugin deprecated
 func New(provider httpclient.Provider) func(*models.DataSource) (plugins.DataPlugin, error) {
 	return func(dsInfo *models.DataSource) (plugins.DataPlugin, error) {
-		transport, err := dsInfo.GetHTTPTransport(provider, customQueryParametersMiddleware())
+		transport, err := dsInfo.GetHTTPTransport(provider, customQueryParametersMiddleware(plog))
 		if err != nil {
 			return nil, err
 		}