Fix linter errors (#5442)

* Remove unused symbols

* Fix bodycloser linter errors

* Fix errcheck linter errors

* Fix staticcheck linter errors

* Use default configuration for nakedret linter

* Fix various linter errors

.golangci.yml

@@ -124,10 +124,6 @@ linters-settings:
     # Select the Go version to target. The default is '1.13'.
     go: "1.22.7"
 
-  nakedret:
-    # make an issue if func has more lines of code than this setting and it has naked returns; default is 30
-    max-func-lines: 0
-
   nolintlint:
     # Enable to ensure that nolint directives are all used. Default is true.
     allow-unused: false

dev-tools/mage/check.go

@@ -24,7 +24,7 @@ import (
 // It checks the file permissions of python test cases and YAML files.
 // It checks .go source files using 'go vet'.
 func Check() error {
-	fmt.Println(">> check: Checking source code for common problems") //nolint:forbidigo // it's ok to use fmt.println in mage
+	fmt.Println(">> check: Checking source code for common problems")
 
 	mg.Deps(GoVet, CheckYAMLNotExecutable, devtools.CheckNoChanges)
 
@@ -69,7 +69,7 @@ func GoVet() error {
 
 // CheckLicenseHeaders checks license headers in .go files.
 func CheckLicenseHeaders() error {
-	fmt.Println(">> fmt - go-licenser: Checking for missing headers") //nolint:forbidigo // it's ok to use fmt.println in mage
+	fmt.Println(">> fmt - go-licenser: Checking for missing headers")
 	mg.Deps(InstallGoLicenser)
 
 	licenser := gotool.Licenser

dev-tools/mage/gotool/go.go

@@ -210,10 +210,6 @@ func runVGo(cmd string, args *Args) error {
 	}, cmd, args)
 }
 
-func runGo(cmd string, args *Args) error {
-	return execGoWith(sh.RunWith, cmd, args)
-}
-
 func execGoWith(
 	fn func(map[string]string, string, ...string) error,
 	cmd string, args *Args,

dev-tools/mage/kubernetes/kubectl.go

@@ -96,23 +96,3 @@ func kubectlIn(env map[string]string, stdout, stderr io.Writer, input string, ar
 
 	return c.Run()
 }
-
-func kubectlStart(env map[string]string, stdout, stderr io.Writer, args ...string) (*exec.Cmd, error) {
-	c := exec.Command("kubectl", args...)
-	c.Env = os.Environ()
-	for k, v := range env {
-		c.Env = append(c.Env, k+"="+v)
-	}
-	c.Stdout = stdout
-	c.Stderr = stderr
-	c.Stdin = nil
-
-	if mg.Verbose() {
-		fmt.Println("exec:", "kubectl", strings.Join(args, " "))
-	}
-
-	if err := c.Start(); err != nil {
-		return nil, err
-	}
-	return c, nil
-}

dev-tools/mage/target/common/package.go

@@ -48,7 +48,11 @@ func PackageSystemTests() error {
 	parent := filepath.Dir(targetFile)
 	if !fileExists(parent) {
 		fmt.Printf(">> creating parent dir: %s", parent)
-		os.Mkdir(parent, 0750)
+		err = os.Mkdir(parent, 0750)
+		if err != nil {
+			fmt.Printf(">> %s", err)
+			return err
+		}
 	}
 
 	err = devtools.Tar(systemTestsDir, targetFile)

internal/pkg/agent/application/monitoring/processes_cloud_test.go

@@ -90,6 +90,7 @@ func TestExpectedCloudProcessID(t *testing.T) {
 	}
 
 	for _, tc := range testcases {
+		tc := tc // make a copy to avoid implicit memory aliasing
 		t.Run(tc.name, func(t *testing.T) {
 			assert.Equal(t, tc.id, expectedCloudProcessID(&tc.component))
 		})
@@ -142,6 +143,7 @@ func TestMatchesCloudProcessID(t *testing.T) {
 	}
 
 	for _, tc := range testcases {
+		tc := tc // make a copy to avoid implicit memory aliasing
 		t.Run(tc.name, func(t *testing.T) {
 			assert.Equal(t, tc.matches, matchesCloudProcessID(&tc.component, tc.processID))
 		})

internal/pkg/agent/application/upgrade/artifact/download/headers_rtt_test.go

@@ -29,7 +29,7 @@ func TestAddingHeaders(t *testing.T) {
 	rtt := WithHeaders(c.Transport, Headers)
 
 	c.Transport = rtt
-	resp, err := c.Get(server.URL)
+	resp, err := c.Get(server.URL) //nolint:noctx // this is fine in tests
 	require.NoError(t, err)
 	b, err := io.ReadAll(resp.Body)
 	defer resp.Body.Close()

internal/pkg/agent/errors/error_test.go

@@ -64,7 +64,8 @@ func TestErrorsWrap(t *testing.T) {
 	ew := fmt.Errorf("wrapper: %w", ce)
 	outer := New(ew)
 
-	outerCustom, ok := outer.(Error)
+	var outerCustom Error
+	ok := errors.As(outer, &outerCustom)
 	if !ok {
 		t.Error("expected Error")
 		return
@@ -109,7 +110,8 @@ func TestErrors(t *testing.T) {
 
 	for _, tc := range cases {
 		actualErr := New(tc.args...)
-		agentErr, ok := actualErr.(Error)
+		var agentErr Error
+		ok := errors.As(actualErr, &agentErr)
 		if !ok {
 			t.Errorf("[%s] expected Error", tc.id)
 			continue
@@ -151,7 +153,8 @@ func TestMetaFold(t *testing.T) {
 	err3 := New("level3", err2, M("key1", "level3"), M("key3", "level3"))
 	err4 := New("level4", err3)
 
-	resultingErr, ok := err4.(Error)
+	var resultingErr Error
+	ok := errors.As(err4, &resultingErr)
 	if !ok {
 		t.Fatal("error is not Error")
 	}
@@ -186,7 +189,8 @@ func TestMetaCallDoesNotModifyCollection(t *testing.T) {
 	err3 := New("level3", err2, M("key1", "level3"), M("key3", "level3"))
 	err4 := New("level4", err3)
 
-	resultingErr, ok := err4.(agentError)
+	var resultingErr agentError
+	ok := errors.As(err4, &resultingErr)
 	if !ok {
 		t.Fatal("error is not Error")
 	}

internal/pkg/fleetapi/uploader/uploader_test.go

@@ -135,6 +135,12 @@ func Test_retrySender_Send(t *testing.T) {
 				assert.Equal(t, tc.err, err)
 				assert.Equal(t, tc.status, resp.StatusCode)
 			}
+			defer func() {
+				if resp != nil && resp.Body != nil {
+					err := resp.Body.Close()
+					assert.NoError(t, err)
+				}
+			}()
 			sender.AssertExpectations(t)
 		})
 	}
@@ -166,6 +172,12 @@ func Test_retrySender_bodyValidation(t *testing.T) {
 		wait: backoff,
 	}
 	resp, err := c.Send(context.Background(), "POST", "/", nil, nil, bytes.NewReader([]byte("abcd")))
+	defer func() {
+		if resp != nil && resp.Body != nil {
+			err := resp.Body.Close()
+			assert.NoError(t, err)
+		}
+	}()
 	require.NoError(t, err)
 	assert.Equal(t, resp.StatusCode, 200)
 	assert.Equal(t, []byte("abcd"), body1)

pkg/component/runtime/service_command.go

@@ -55,24 +55,22 @@ func executeCommand(ctx context.Context, log *logger.Logger, binaryPath string,
 	// channel for the last error message from the stderr output
 	errch := make(chan string, 1)
 	ctxStderr := contextio.NewReader(ctx, proc.Stderr)
-	if ctxStderr != nil {
-		go func() {
-			var errText string
-			scanner := bufio.NewScanner(ctxStderr)
-			for scanner.Scan() {
-				line := scanner.Text()
-				if len(line) > 0 {
-					txt := strings.TrimSpace(line)
-					if len(txt) > 0 {
-						errText = txt
-						// Log error output line
-						log.Error(errText)
-					}
+	go func() {
+		var errText string
+		scanner := bufio.NewScanner(ctxStderr)
+		for scanner.Scan() {
+			line := scanner.Text()
+			if len(line) > 0 {
+				txt := strings.TrimSpace(line)
+				if len(txt) > 0 {
+					errText = txt
+					// Log error output line
+					log.Error(errText)
 				}
 			}
-			errch <- errText
-		}()
-	}
+		}
+		errch <- errText
+	}()
 
 	procState := <-proc.Wait()
 	if errors.Is(ctx.Err(), context.DeadlineExceeded) {

pkg/control/v1/client/dial.go

@@ -18,7 +18,7 @@ import (
 )
 
 func dialContext(ctx context.Context) (*grpc.ClientConn, error) {
-	return grpc.DialContext(
+	return grpc.DialContext( //nolint:staticcheck // Only the deprecated version allows this call to be blocking
 		ctx,
 		strings.TrimPrefix(control.Address(), "unix://"),
 		grpc.WithTransportCredentials(insecure.NewCredentials()),

pkg/control/v1/client/dial_windows.go

@@ -19,7 +19,7 @@ import (
 )
 
 func dialContext(ctx context.Context) (*grpc.ClientConn, error) {
-	return grpc.DialContext(
+	return grpc.DialContext( //nolint:staticcheck // Only the deprecated version allows this call to be blocking
 		ctx,
 		control.Address(),
 		grpc.WithTransportCredentials(insecure.NewCredentials()),

pkg/control/v2/client/dial.go

@@ -21,7 +21,7 @@ func dialContext(ctx context.Context, address string, maxMsgSize int, opts ...gr
 		grpc.WithContextDialer(dialer),
 		grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(maxMsgSize)),
 	)
-	return grpc.DialContext(ctx, address, opts...)
+	return grpc.DialContext(ctx, address, opts...) //nolint:staticcheck // Only the deprecated version allows this call to be blocking
 }
 
 func dialer(ctx context.Context, addr string) (net.Conn, error) {

pkg/control/v2/client/dial_windows.go

@@ -23,7 +23,7 @@ func dialContext(ctx context.Context, address string, maxMsgSize int, opts ...gr
 		grpc.WithContextDialer(dialer),
 		grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(maxMsgSize)),
 	)
-	return grpc.DialContext(ctx, address, opts...)
+	return grpc.DialContext(ctx, address, opts...) //nolint:staticcheck // Only the deprecated version allows this call to be blocking
 }
 
 func dialer(ctx context.Context, addr string) (net.Conn, error) {

testing/upgradetest/upgrader.go

@@ -516,7 +516,7 @@ func WaitHealthyAndVersion(ctx context.Context, f *atesting.Fixture, versionInfo
 			// If we're in an upgrade process, the versions might not match
 			// so we wait to see if we get to a stable version
 			if errors.Is(err, ErrVerMismatch) {
-				logger.Logf("version mismatch, ignoring it, time until timeout: %s", deadline.Sub(time.Now()))
+				logger.Logf("version mismatch, ignoring it, time until timeout: %s", time.Until(deadline))
 				continue
 			}
 			if err == nil {