Merge pull request #53880 from wackxu/kubeconfig

Automatic merge from submit-queue (batch tested with PRs 51423, 53880). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

prevent the same path load multiple times

**What this PR does / why we need it**:

prevent the same path load multiple times，if there are several same path, we only load one time

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #53723

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```

staging/src/k8s.io/client-go/tools/clientcmd/config.go

@@ -68,7 +68,9 @@ func (o *PathOptions) GetEnvVarFiles() []string {
 		return []string{}
 	}
 
-	return filepath.SplitList(envVarValue)
+	fileList := filepath.SplitList(envVarValue)
+	// prevent the same path load multiple times
+	return deduplicate(fileList)
 }
 
 func (o *PathOptions) GetLoadingPrecedence() []string {

staging/src/k8s.io/client-go/tools/clientcmd/loader.go

@@ -139,7 +139,9 @@ func NewDefaultClientConfigLoadingRules() *ClientConfigLoadingRules {
 
 	envVarFiles := os.Getenv(RecommendedConfigPathEnvVar)
 	if len(envVarFiles) != 0 {
-		chain = append(chain, filepath.SplitList(envVarFiles)...)
+		fileList := filepath.SplitList(envVarFiles)
+		// prevent the same path load multiple times
+		chain = append(chain, deduplicate(fileList)...)
 
 	} else {
 		chain = append(chain, RecommendedHomeFile)
@@ -615,3 +617,17 @@ func MakeRelative(path, base string) (string, error) {
 	}
 	return path, nil
 }
+
+// deduplicate removes any duplicated values and returns a new slice, keeping the order unchanged
+func deduplicate(s []string) []string {
+	encountered := map[string]bool{}
+	ret := make([]string, 0)
+	for i := range s {
+		if encountered[s[i]] {
+			continue
+		}
+		encountered[s[i]] = true
+		ret = append(ret, s[i])
+	}
+	return ret
+}

staging/src/k8s.io/client-go/tools/clientcmd/loader_test.go

@@ -592,3 +592,30 @@ func Example_mergingEverythingNoConflicts() {
 	//   user:
 	//     token: red-token
 }
+
+func TestDeduplicate(t *testing.T) {
+	testCases := []struct {
+		src    []string
+		expect []string
+	}{
+		{
+			src:    []string{"a", "b", "c", "d", "e", "f"},
+			expect: []string{"a", "b", "c", "d", "e", "f"},
+		},
+		{
+			src:    []string{"a", "b", "c", "b", "e", "f"},
+			expect: []string{"a", "b", "c", "e", "f"},
+		},
+		{
+			src:    []string{"a", "a", "b", "b", "c", "b"},
+			expect: []string{"a", "b", "c"},
+		},
+	}
+
+	for _, testCase := range testCases {
+		get := deduplicate(testCase.src)
+		if !reflect.DeepEqual(get, testCase.expect) {
+			t.Errorf("expect: %v, get: %v", testCase.expect, get)
+		}
+	}
+}