refactor: move from io/ioutil to io and os packages (#5266)

The io/ioutil package has been deprecated as of Go 1.16 [1]. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.

[1]: https://golang.org/doc/go1.16#ioutil
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

pkg/apiserver/authentication/identityprovider/aliyunidaas/idaas.go

@@ -19,7 +19,7 @@ package aliyunidaas
 import (
 	"encoding/json"
 	"errors"
-	"io/ioutil"
+	"io"
 	"net/http"
 
 	"github.com/mitchellh/mapstructure"
@@ -134,7 +134,7 @@ func (a *aliyunIDaaS) IdentityExchangeCallback(req *http.Request) (identityprovi
 		return nil, err
 	}
 
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, err
 	}

pkg/apiserver/authentication/identityprovider/github/github.go

@@ -20,7 +20,7 @@ import (
 	"context"
 	"crypto/tls"
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"time"
 
@@ -190,7 +190,7 @@ func (g *github) IdentityExchangeCallback(req *http.Request) (identityprovider.I
 		return nil, err
 	}
 
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, err
 	}

pkg/apiserver/authentication/identityprovider/ldap/ldap.go

@@ -21,7 +21,7 @@ import (
 	"crypto/x509"
 	"encoding/base64"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"time"
 
 	"github.com/go-ldap/ldap"
@@ -186,7 +186,7 @@ func (l *ldapProvider) newConn() (*ldap.Conn, error) {
 	var err error
 	// Load CA cert
 	if l.RootCA != "" {
-		if caCert, err = ioutil.ReadFile(l.RootCA); err != nil {
+		if caCert, err = os.ReadFile(l.RootCA); err != nil {
 			klog.Error(err)
 			return nil, err
 		}

pkg/apiserver/authentication/identityprovider/ldap/ldap_test.go

@@ -17,7 +17,6 @@ limitations under the License.
 package ldap
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -74,7 +73,7 @@ func TestLdapProvider_Authenticate(t *testing.T) {
 	if configFile == "" {
 		t.Skip("Skipped")
 	}
-	options, err := ioutil.ReadFile(configFile)
+	options, err := os.ReadFile(configFile)
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/apiserver/authentication/identityprovider/oidc/oidc.go

@@ -23,7 +23,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 
 	"kubesphere.io/kubesphere/pkg/utils/sliceutil"
@@ -251,7 +251,7 @@ func (o *oidcProvider) IdentityExchangeCallback(req *http.Request) (identityprov
 			if err != nil {
 				return nil, fmt.Errorf("failed to fetch userinfo: %v", err)
 			}
-			data, err := ioutil.ReadAll(resp.Body)
+			data, err := io.ReadAll(resp.Body)
 			if err != nil {
 				return nil, fmt.Errorf("failed to fetch userinfo: %v", err)
 			}