[fix]: enhance kubelet package impl

pkg/kubelet/kubelet_pod_lister.go

@@ -37,8 +37,9 @@ const (
 )
 
 var (
-	podURL string
-	client http.Client
+	podURL      string
+	client      http.Client
+	bearerToken string
 )
 
 func init() {
@@ -55,29 +56,49 @@ func init() {
 	client = http.Client{}
 }
 
-func httpGet(url string) (*http.Response, error) {
-	objToken, err := os.ReadFile(saPath)
+func loadToken(path string) (string, error) {
+	objToken, err := os.ReadFile(path)
 	if err != nil {
-		return nil, fmt.Errorf("failed to read from %q: %v", saPath, err)
+		return "", fmt.Errorf("failed to read from %q: %v", path, err)
 	}
-	token := string(objToken)
+	return "Bearer " + string(objToken), nil
+}
 
-	var bearer = "Bearer " + token
+func doFetchPod(url string) (*http.Response, error) {
 	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, http.NoBody)
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Add("Authorization", bearer)
+	req.Header.Add("Authorization", bearerToken)
 	resp, err := client.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get response from %q: %v", url, err)
 	}
 	return resp, err
 }
 
+func httpGet(path, url string) (*http.Response, error) {
+	var err error
+	if bearerToken == "" {
+		bearerToken, err = loadToken(path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read from %q: %v", path, err)
+		}
+	}
+	resp, err := doFetchPod(url)
+	if resp != nil && resp.StatusCode > 399 && resp.StatusCode < 500 { // if response in 4xx retry once
+		bearerToken, err = loadToken(path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read from %q: %v", path, err)
+		}
+		resp, err = doFetchPod(url)
+	}
+	return resp, err
+}
+
 // ListPods obtains PodList
 func (k *KubeletPodLister) ListPods() (*[]corev1.Pod, error) {
-	resp, err := httpGet(podURL)
+	resp, err := httpGet(saPath, podURL)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get response: %v", err)
 	}

pkg/kubelet/kubelet_pod_lister_test.go

@@ -0,0 +1,124 @@
+/*
+Copyright 2024.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kubelet
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"sync"
+	"testing"
+
+	. "github.com/onsi/gomega"
+)
+
+func TestDoFetchPod(t *testing.T) {
+	g := NewWithT(t)
+	svr := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "dummy")
+	}))
+	defer svr.Close()
+	res, err := doFetchPod(svr.URL)
+	g.Expect(err).NotTo(HaveOccurred())
+	defer res.Body.Close()
+	g.Expect(res.StatusCode).To(Equal(http.StatusOK))
+	bearerToken = "dummy"
+	res, err = httpGet("", svr.URL)
+	g.Expect(err).NotTo(HaveOccurred())
+	defer res.Body.Close()
+	g.Expect(res.StatusCode).To(Equal(http.StatusOK))
+}
+
+func TestDoFetchPodWithError(t *testing.T) {
+	g := NewWithT(t)
+	svr := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "dummy")
+	}))
+	res, err := doFetchPod(svr.URL)
+	g.Expect(err).To(HaveOccurred())
+	g.Expect(res).To(BeNil())
+	if res != nil {
+		defer res.Body.Close()
+	}
+	res, err = httpGet("", svr.URL)
+	if res != nil {
+		defer res.Body.Close()
+	}
+	g.Expect(err).To(HaveOccurred())
+	g.Expect(res).To(BeNil())
+}
+
+func TestLoadToken(t *testing.T) {
+	g := NewWithT(t)
+	tmpDir, err := os.MkdirTemp("", "kepler-tmp-")
+	g.Expect(err).NotTo(HaveOccurred())
+	defer os.RemoveAll(tmpDir)
+
+	TokenFile, err := os.CreateTemp(tmpDir, "kubeletToken")
+	g.Expect(err).NotTo(HaveOccurred())
+	_, err = TokenFile.WriteString("token")
+	g.Expect(err).NotTo(HaveOccurred())
+	TokenFile.Close()
+
+	token, err := loadToken(TokenFile.Name())
+	g.Expect(err).NotTo(HaveOccurred())
+	g.Expect(token).To(Equal("Bearer token"))
+
+	var once sync.Once
+	svr := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		once.Do(func() {
+			w.WriteHeader(http.StatusUnauthorized)
+		})
+		fmt.Fprintf(w, "dummy")
+	}))
+	defer svr.Close()
+
+	res, err := httpGet(TokenFile.Name(), svr.URL)
+	g.Expect(err).NotTo(HaveOccurred())
+	defer res.Body.Close()
+	g.Expect(res.StatusCode).To(Equal(http.StatusOK))
+}
+
+func TestHttpGet(t *testing.T) {
+	g := NewWithT(t)
+	tmpDir, err := os.MkdirTemp("", "kepler-tmp-")
+	g.Expect(err).NotTo(HaveOccurred())
+	defer os.RemoveAll(tmpDir)
+
+	TokenFile, err := os.CreateTemp(tmpDir, "kubeletToken")
+	g.Expect(err).NotTo(HaveOccurred())
+	_, err = TokenFile.WriteString("token")
+	g.Expect(err).NotTo(HaveOccurred())
+	TokenFile.Close()
+
+	bearerToken = ""
+	g.Expect(bearerToken).To(Equal("")) // need this to pass lint
+	var once sync.Once
+	svr := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		once.Do(func() {
+			w.WriteHeader(http.StatusUnauthorized)
+		})
+		fmt.Fprintf(w, "dummy")
+	}))
+	defer svr.Close()
+
+	res, err := httpGet(TokenFile.Name(), svr.URL)
+	g.Expect(err).NotTo(HaveOccurred())
+	defer res.Body.Close()
+	g.Expect(res.StatusCode).To(Equal(http.StatusOK))
+}