chore(lint): fix linter issues

- Adapted error comparison according to linter recommendation
- Disabled noctx linting for http request where canceling makes no sense
- Disabled nilerror linting where nil error is returned on purpose
- Disabled makezero linter where slice is explicitly deepcopied

integration/integration_test.go

@@ -714,18 +714,18 @@ func TestExitCodePropagation(t *testing.T) {
 }
 
 type fileDiff struct {
-	Name string
-	Size int
+	Name string `json:"Name"`
+	Size int    `json:"Size"`
 }
 
 type fileDiffResult struct {
-	Adds []fileDiff
-	Dels []fileDiff
+	Adds []fileDiff `json:"Adds"`
+	Dels []fileDiff `json:"Dels"`
 }
 
 type metaDiffResult struct {
-	Adds []string
-	Dels []string
+	Adds []string `json:"Adds"`
+	Dels []string `json:"Dels"`
 }
 
 type diffOutput struct {

pkg/buildcontext/https.go

@@ -49,7 +49,7 @@ func (h *HTTPSTar) UnpackTarFromBuildContext() (directory string, err error) {
 
 	// Download tar file from remote https server
 	// and save it into the target tar file
-	resp, err := http.Get(h.context)
+	resp, err := http.Get(h.context) //nolint:noctx
 	if err != nil {
 		return
 	}

pkg/cache/errors.go

@@ -16,15 +16,13 @@ limitations under the License.
 
 package cache
 
+import "errors"
+
 // IsAlreadyCached returns true if the supplied error is of the type AlreadyCachedErr
 // otherwise it returns false.
 func IsAlreadyCached(err error) bool {
-	switch err.(type) {
-	case AlreadyCachedErr:
-		return true
-	}
-
-	return false
+	var e AlreadyCachedErr
+	return errors.As(err, &e)
 }
 
 // AlreadyCachedErr is returned when the Docker image requested for caching is already
@@ -39,13 +37,9 @@ func (a AlreadyCachedErr) Error() string {
 
 // IsNotFound returns true if the supplied error is of the type NotFoundErr
 // otherwise it returns false.
-func IsNotFound(e error) bool {
-	switch e.(type) {
-	case NotFoundErr:
-		return true
-	}
-
-	return false
+func IsNotFound(err error) bool {
+	var e NotFoundErr
+	return errors.As(err, &e)
 }
 
 // NotFoundErr is returned when the requested Docker image is not present in the cache.
@@ -59,13 +53,9 @@ func (e NotFoundErr) Error() string {
 
 // IsExpired returns true if the supplied error is of the type ExpiredErr
 // otherwise it returns false.
-func IsExpired(e error) bool {
-	switch e.(type) {
-	case ExpiredErr:
-		return true
-	}
-
-	return false
+func IsExpired(err error) bool {
+	var e ExpiredErr
+	return errors.As(err, &e)
 }
 
 // ExpiredErr is returned when the requested Docker image is present in the cache, but is

pkg/commands/copy_test.go

@@ -375,7 +375,7 @@ func Test_resolveIfSymlink(t *testing.T) {
 	for i, c := range cases {
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
 			res, e := resolveIfSymlink(c.destPath)
-			if e != c.err {
+			if !errors.Is(e, c.err) {
 				t.Errorf("%s: expected %v but got %v", c.destPath, c.err, e)
 			}
 

pkg/commands/volume.go

@@ -54,7 +54,7 @@ func (v *VolumeCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.
 		if _, err := os.Stat(volume); os.IsNotExist(err) {
 			logrus.Infof("Creating directory %s", volume)
 			if err := os.MkdirAll(volume, 0755); err != nil {
-				return fmt.Errorf("could not create directory for volume %s: %s", volume, err)
+				return fmt.Errorf("could not create directory for volume %s: %w", volume, err)
 			}
 		}
 	}

pkg/dockerfile/buildargs.go

@@ -55,7 +55,8 @@ func (b *BuildArgs) ReplacementEnvs(envs []string) []string {
 	resultEnv := make([]string, len(envs))
 	copy(resultEnv, envs)
 	filtered := b.FilterAllowed(envs)
-	return append(resultEnv, filtered...)
+	// Disable makezero linter, since the previous make is paired with a same sized copy
+	return append(resultEnv, filtered...) //nolint:makezero
 }
 
 // AddMetaArgs adds the supplied args map to b's allowedMetaArgs

pkg/dockerfile/dockerfile.go

@@ -40,7 +40,7 @@ func ParseStages(opts *config.KanikoOptions) ([]instructions.Stage, []instructio
 	var d []uint8
 	match, _ := regexp.MatchString("^https?://", opts.DockerfilePath)
 	if match {
-		response, e := http.Get(opts.DockerfilePath)
+		response, e := http.Get(opts.DockerfilePath) //nolint:noctx
 		if e != nil {
 			return nil, nil, e
 		}

pkg/executor/push_test.go

@@ -127,7 +127,7 @@ func TestHeaderAdded(t *testing.T) {
 				os.Setenv("UPSTREAM_CLIENT_TYPE", test.upstream)
 				defer func() { os.Unsetenv("UPSTREAM_CLIENT_TYPE") }()
 			}
-			req, err := http.NewRequest("GET", "dummy", nil)
+			req, err := http.NewRequest("GET", "dummy", nil) //nolint:noctx
 			if err != nil {
 				t.Fatalf("culd not create a req due to %s", err)
 			}

pkg/snapshot/snapshot.go

@@ -17,6 +17,7 @@ limitations under the License.
 package snapshot
 
 import (
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -262,7 +263,7 @@ func addParentDirectories(t util.Tar, addedPaths map[string]bool, path string) e
 // filesWithLinks returns the symlink and the target path if its exists.
 func filesWithLinks(path string) ([]string, error) {
 	link, err := util.GetSymLink(path)
-	if err == util.ErrNotSymLink {
+	if errors.Is(err, util.ErrNotSymLink) {
 		return []string{path}, nil
 	} else if err != nil {
 		return nil, err
@@ -272,7 +273,7 @@ func filesWithLinks(path string) ([]string, error) {
 		link = filepath.Join(filepath.Dir(path), link)
 	}
 	if _, err := os.Stat(link); err != nil {
-		return []string{path}, nil
+		return []string{path}, nil //nolint:nilerr
 	}
 	return []string{path, link}, nil
 }

pkg/snapshot/snapshot_test.go

@@ -76,7 +76,7 @@ func TestSnapshotFSFileChange(t *testing.T) {
 	actualFiles := []string{}
 	for {
 		hdr, err := tr.Next()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			break
 		}
 
@@ -166,7 +166,7 @@ func TestSnapshotFSChangePermissions(t *testing.T) {
 	foundFiles := []string{}
 	for {
 		hdr, err := tr.Next()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			break
 		}
 		foundFiles = append(foundFiles, hdr.Name)
@@ -249,7 +249,7 @@ func TestEmptySnapshotFS(t *testing.T) {
 	}
 	tr := tar.NewReader(f)
 
-	if _, err := tr.Next(); err != io.EOF {
+	if _, err := tr.Next(); !errors.Is(err, io.EOF) {
 		t.Fatal("no files expected in tar, found files.")
 	}
 }
@@ -560,7 +560,7 @@ func TestSnapshotOmitsUnameGname(t *testing.T) {
 	tr := tar.NewReader(f)
 	for {
 		hdr, err := tr.Next()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			break
 		}
 		if err != nil {
@@ -637,7 +637,7 @@ func listFilesInTar(path string) ([]string, error) {
 	var files []string
 	for {
 		hdr, err := tr.Next()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			break
 		}
 		if err != nil {

pkg/util/command_util.go

@@ -291,7 +291,7 @@ func IsSrcRemoteFileURL(rawurl string) bool {
 	if err != nil {
 		return false
 	}
-	_, err = http.Get(rawurl)
+	_, err = http.Get(rawurl) //nolint:noctx
 	return err == nil
 }
 

pkg/util/fs_util.go

@@ -167,7 +167,7 @@ func GetFSFromLayers(root string, layers []v1.Layer, opts ...FSOpt) ([]string, e
 		tr := tar.NewReader(r)
 		for {
 			hdr, err := tr.Next()
-			if err == io.EOF {
+			if errors.Is(err, io.EOF) {
 				break
 			}
 
@@ -221,7 +221,7 @@ func DeleteFilesystem() error {
 	return filepath.Walk(config.RootDir, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			// ignore errors when deleting.
-			return nil
+			return nil //nolint:nilerr
 		}
 
 		if CheckIgnoreList(path) {
@@ -270,7 +270,7 @@ func UnTar(r io.Reader, dest string) ([]string, error) {
 	tr := tar.NewReader(r)
 	for {
 		hdr, err := tr.Next()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			break
 		}
 		if err != nil {
@@ -450,7 +450,7 @@ func DetectFilesystemIgnoreList(path string) error {
 	for {
 		line, err := reader.ReadString('\n')
 		logrus.Tracef("Read the following line from %s: %s", path, line)
-		if err != nil && err != io.EOF {
+		if err != nil && !errors.Is(err, io.EOF) {
 			return err
 		}
 		lineArr := strings.Split(line, " ")
@@ -604,7 +604,7 @@ func AddVolumePathToIgnoreList(path string) {
 //     - destination will have permissions of 0600
 //     - If remote file has HTTP Last-Modified header, we set the mtime of the file to that timestamp
 func DownloadFileToDest(rawurl, dest string, uid, gid int64) error {
-	resp, err := http.Get(rawurl)
+	resp, err := http.Get(rawurl) //nolint:noctx
 	if err != nil {
 		return err
 	}

pkg/util/tar_util.go

@@ -80,7 +80,7 @@ func (t *Tar) Close() {
 func (t *Tar) AddFileToTar(p string) error {
 	i, err := os.Lstat(p)
 	if err != nil {
-		return fmt.Errorf("Failed to get file info for %s: %s", p, err)
+		return fmt.Errorf("Failed to get file info for %s: %w", p, err)
 	}
 	linkDst := ""
 	if i.Mode()&os.ModeSymlink != 0 {
@@ -156,7 +156,7 @@ func writeSecurityXattrToToFile(path string, hdr *tar.Header) error {
 	}
 	if capability, ok := hdr.Xattrs[securityCapabilityXattr]; ok {
 		err := system.Lsetxattr(path, securityCapabilityXattr, []byte(capability), 0)
-		if err != nil && !errors.Is(err, syscall.EOPNOTSUPP) && err != system.ErrNotSupportedPlatform {
+		if err != nil && !errors.Is(err, syscall.EOPNOTSUPP) && !errors.Is(err, system.ErrNotSupportedPlatform) {
 			return errors.Wrapf(err, "failed to write %q attribute to %q", securityCapabilityXattr, path)
 		}
 	}
@@ -170,7 +170,7 @@ func readSecurityXattrToTarHeader(path string, hdr *tar.Header) error {
 		hdr.Xattrs = make(map[string]string)
 	}
 	capability, err := system.Lgetxattr(path, securityCapabilityXattr)
-	if err != nil && !errors.Is(err, syscall.EOPNOTSUPP) && err != system.ErrNotSupportedPlatform {
+	if err != nil && !errors.Is(err, syscall.EOPNOTSUPP) && !errors.Is(err, system.ErrNotSupportedPlatform) {
 		return errors.Wrapf(err, "failed to read %q attribute from %q", securityCapabilityXattr, path)
 	}
 	if capability != nil {

pkg/util/util.go

@@ -30,6 +30,7 @@ import (
 	"time"
 
 	"github.com/minio/highwayhash"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 )
@@ -195,7 +196,7 @@ func Lgetxattr(path string, attr string) ([]byte, error) {
 	dest := make([]byte, 128)
 	sz, errno := unix.Lgetxattr(path, attr, dest)
 
-	for errno == unix.ERANGE {
+	for errors.Is(errno, unix.ERANGE) {
 		// Buffer too small, use zero-sized buffer to get the actual size
 		sz, errno = unix.Lgetxattr(path, attr, []byte{})
 		if errno != nil {
@@ -206,7 +207,7 @@ func Lgetxattr(path string, attr string) ([]byte, error) {
 	}
 
 	switch {
-	case errno == unix.ENODATA:
+	case errors.Is(errno, unix.ENODATA):
 		return nil, nil
 	case errno != nil:
 		return nil, errno

testutil/util.go

@@ -107,7 +107,7 @@ func checkErr(shouldErr bool, err error) error {
 		return fmt.Errorf("Expected error, but returned none")
 	}
 	if err != nil && !shouldErr {
-		return fmt.Errorf("Unexpected error: %s", err)
+		return fmt.Errorf("Unexpected error: %w", err)
 	}
 	return nil
 }