From 8b88665b8cd74a832c7b8a249bcdcbb44e5f095d Mon Sep 17 00:00:00 2001
From: Bastian de Byl <bastian.debyl@meltwater.com>
Date: Fri, 15 Jul 2022 15:20:37 -0400
Subject: [PATCH] dependabot-1 Major linting fixes, code cleanup

---
 .errcheck_excludes                            |  3 ++-
 .golangci.yml                                 |  9 ++++++--
 Makefile                                      |  2 +-
 archive/archive.go                            |  6 ++---
 archive/gzip/gzip.go                          | 19 +++++++++++----
 archive/gzip/gzip_test.go                     |  2 +-
 archive/tar/tar.go                            | 17 +++++++-------
 archive/tar/tar_test.go                       |  2 +-
 archive/zstd/zstd.go                          | 22 ++++++++++++------
 archive/zstd/zstd_test.go                     |  2 +-
 cache/cache.go                                |  3 +--
 cache/flusher.go                              |  5 ++--
 cache/rebuilder.go                            | 11 ++++-----
 cache/restorer.go                             |  7 +++---
 go.mod                                        |  3 +--
 go.sum                                        |  6 ++---
 internal/io.go                                |  2 +-
 internal/logger.go                            |  3 ++-
 internal/plugin/plugin.go                     |  9 ++++----
 internal/plugin/plugin_test.go                |  2 +-
 key/generator/metadata.go                     | 22 ++++++++++++++----
 key/generator/metadata_test.go                |  2 +-
 main.go                                       | 12 +++++-----
 storage/backend/azure/azure.go                | 11 +++++----
 storage/backend/azure/azure_test.go           |  2 +-
 storage/backend/backend.go                    |  5 ++--
 storage/backend/filesystem/filesystem.go      | 12 ++++++----
 storage/backend/filesystem/filesystem_test.go |  2 +-
 storage/backend/gcs/gcs.go                    | 19 ++++++++++-----
 storage/backend/gcs/gcs_test.go               |  2 +-
 storage/backend/s3/s3.go                      | 10 ++++----
 storage/backend/s3/s3_test.go                 |  2 +-
 storage/backend/sftp/sftp.go                  | 16 +++++++++----
 storage/backend/sftp/sftp_test.go             |  2 +-
 storage/storage.go                            | 23 +++++++++++++++----
 35 files changed, 170 insertions(+), 107 deletions(-)

diff --git a/.errcheck_excludes b/.errcheck_excludes
index 97b97714..9ae86417 100644
--- a/.errcheck_excludes
+++ b/.errcheck_excludes
@@ -1 +1,2 @@
-(github.com/go-kit/kit/log.Logger).Log
+(github.com/go-kit/log.Logger).Log
+b.logger.Log
diff --git a/.golangci.yml b/.golangci.yml
index 31a4a3b3..f1b8d7e8 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -6,11 +6,17 @@ run:
   tests: false
   modules-download-mode: vendor
   timeout: 5m
+  skip-dirs:
+    - test
 
 linters:
   enable-all: true
   disable:
+    - exhaustivestruct
+    - exhaustruct
     - goerr113
+    - ireturn
+    - maintidx
     - varnamelen
 
 linters-settings:
@@ -20,5 +26,4 @@ linters-settings:
     line-length: 120
   funlen:
     lines: 70
-    statements: 40
-
+    statements: 40
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 6fbfcc62..0de33d31 100644
--- a/Makefile
+++ b/Makefile
@@ -132,7 +132,7 @@ test-e2e: $(GOTEST) ; $(info $(M) running test-e2e )
 lint: ## Runs golangci-lint analysis
 lint:
 	# Check .golangci.yml for configuration
-	$(Q) $(GOLANGCI_LINT) run -v --enable-all --skip-dirs tmp -c .golangci.yml
+	$(Q) $(GOLANGCI_LINT) run -v --skip-dirs tmp -c .golangci.yml
 
 .PHONY: fix
 fix: ## Runs golangci-lint fix
diff --git a/archive/archive.go b/archive/archive.go
index 6174a297..8a277688 100644
--- a/archive/archive.go
+++ b/archive/archive.go
@@ -4,12 +4,11 @@ import (
 	"compress/flate"
 	"io"
 
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/archive/gzip"
 	"github.com/meltwater/drone-cache/archive/tar"
 	"github.com/meltwater/drone-cache/archive/zstd"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
 )
 
 const (
@@ -51,6 +50,7 @@ func FromFormat(logger log.Logger, root string, format string, opts ...Option) A
 		return zstd.New(logger, root, options.skipSymlinks, options.compressionLevel)
 	default:
 		level.Error(logger).Log("msg", "unknown archive format", "format", format)
+
 		return tar.New(logger, root, options.skipSymlinks) // DefaultArchiveFormat
 	}
 }
diff --git a/archive/gzip/gzip.go b/archive/gzip/gzip.go
index d874e27b..c1cf4c7f 100644
--- a/archive/gzip/gzip.go
+++ b/archive/gzip/gzip.go
@@ -5,10 +5,9 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/archive/tar"
 	"github.com/meltwater/drone-cache/internal"
-
-	"github.com/go-kit/kit/log"
 )
 
 // Archive implements archive for gzip.
@@ -34,17 +33,27 @@ func (a *Archive) Create(srcs []string, w io.Writer) (int64, error) {
 
 	defer internal.CloseWithErrLogf(a.logger, gw, "gzip writer")
 
-	return tar.New(a.logger, a.root, a.skipSymlinks).Create(srcs, gw)
+	wBytes, err := tar.New(a.logger, a.root, a.skipSymlinks).Create(srcs, gw)
+	if err != nil {
+		return 0, fmt.Errorf("writing create archive bytes: %w", err)
+	}
+
+	return wBytes, nil
 }
 
 // Extract reads content from the given archive reader and restores it to the destination, returns written bytes.
 func (a *Archive) Extract(dst string, r io.Reader) (int64, error) {
 	gr, err := gzip.NewReader(r)
 	if err != nil {
-		return 0, err
+		return 0, fmt.Errorf("create archive extractor: %w", err)
 	}
 
 	defer internal.CloseWithErrLogf(a.logger, gr, "gzip reader")
 
-	return tar.New(a.logger, a.root, a.skipSymlinks).Extract(dst, gr)
+	eBytes, err := tar.New(a.logger, a.root, a.skipSymlinks).Extract(dst, gr)
+	if err != nil {
+		return 0, fmt.Errorf("extracting archive bytes: %w", err)
+	}
+
+	return eBytes, nil
 }
diff --git a/archive/gzip/gzip_test.go b/archive/gzip/gzip_test.go
index 91e81ed3..3903a4db 100644
--- a/archive/gzip/gzip_test.go
+++ b/archive/gzip/gzip_test.go
@@ -9,7 +9,7 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 
 	"github.com/meltwater/drone-cache/archive/tar"
 	"github.com/meltwater/drone-cache/test"
diff --git a/archive/tar/tar.go b/archive/tar/tar.go
index 1896b1ef..ab5130f5 100644
--- a/archive/tar/tar.go
+++ b/archive/tar/tar.go
@@ -10,11 +10,10 @@ import (
 	"strings"
 
 	"github.com/go-kit/log"
-
 	"github.com/meltwater/drone-cache/internal"
 )
 
-const defaultDirPermission = 0755
+const defaultDirPermission = 0o755
 
 var (
 	// ErrSourceNotReachable means that given source is not reachable.
@@ -57,7 +56,7 @@ func (a *Archive) Create(srcs []string, w io.Writer) (int64, error) {
 	return written, nil
 }
 
-// nolint: lll
+// nolint: lll, cyclop
 func writeToArchive(tw *tar.Writer, root string, skipSymlinks bool, written *int64) func(string, os.FileInfo, error) error {
 	return func(path string, fi os.FileInfo, err error) error {
 		if err != nil {
@@ -146,7 +145,7 @@ func createSymlinkHeader(fi os.FileInfo, path string) (*tar.Header, error) {
 	return h, nil
 }
 
-func writeFileToArchive(tw io.Writer, path string) (n int64, err error) {
+func writeFileToArchive(tw io.Writer, path string) (int64, error) {
 	f, err := os.Open(path)
 	if err != nil {
 		return 0, fmt.Errorf("open file <%s>, %w", path, err)
@@ -163,6 +162,7 @@ func writeFileToArchive(tw io.Writer, path string) (n int64, err error) {
 }
 
 // Extract reads content from the given archive reader and restores it to the destination, returns written bytes.
+// nolint: cyclop
 func (a *Archive) Extract(dst string, r io.Reader) (int64, error) {
 	var (
 		written int64
@@ -173,7 +173,7 @@ func (a *Archive) Extract(dst string, r io.Reader) (int64, error) {
 		h, err := tr.Next()
 
 		switch {
-		case err == io.EOF: // if no more files are found return
+		case errors.Is(err, io.EOF): // if no more files are found return
 			return written, nil
 		case err != nil: // return any other error
 			return written, fmt.Errorf("tar reader <%v>, %w", err, ErrArchiveNotReadable)
@@ -241,7 +241,7 @@ func extractDir(h *tar.Header, target string) error {
 	return nil
 }
 
-func extractRegular(h *tar.Header, tr io.Reader, target string) (n int64, err error) {
+func extractRegular(h *tar.Header, tr io.Reader, target string) (int64, error) {
 	f, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR, os.FileMode(h.Mode))
 	if err != nil {
 		return 0, fmt.Errorf("open extracted file for writing <%s>, %w", target, err)
@@ -282,9 +282,8 @@ func extractLink(h *tar.Header, target string) error {
 }
 
 func unlink(path string) error {
-	_, err := os.Lstat(path)
-	if err == nil {
-		return os.Remove(path)
+	if _, err := os.Lstat(path); err == nil {
+		return fmt.Errorf("error with unlinking: %w", os.Remove(path))
 	}
 
 	return nil
diff --git a/archive/tar/tar_test.go b/archive/tar/tar_test.go
index c9a36881..6506c449 100644
--- a/archive/tar/tar_test.go
+++ b/archive/tar/tar_test.go
@@ -9,7 +9,7 @@ import (
 
 	"github.com/meltwater/drone-cache/test"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 )
 
 var (
diff --git a/archive/zstd/zstd.go b/archive/zstd/zstd.go
index a92034d0..b28164bc 100644
--- a/archive/zstd/zstd.go
+++ b/archive/zstd/zstd.go
@@ -4,12 +4,10 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/go-kit/log"
 	"github.com/klauspost/compress/zstd"
-
 	"github.com/meltwater/drone-cache/archive/tar"
 	"github.com/meltwater/drone-cache/internal"
-
-	"github.com/go-kit/kit/log"
 )
 
 // Archive implements archive for zstd.
@@ -30,22 +28,32 @@ func New(logger log.Logger, root string, skipSymlinks bool, compressionLevel int
 func (a *Archive) Create(srcs []string, w io.Writer) (int64, error) {
 	zw, err := zstd.NewWriter(w, zstd.WithEncoderLevel(zstd.EncoderLevelFromZstd(a.compressionLevel)))
 	if err != nil {
-		return 0, fmt.Errorf("create archive writer, %w", err)
+		return 0, fmt.Errorf("zstd create archive writer, %w", err)
 	}
 
 	defer internal.CloseWithErrLogf(a.logger, zw, "zstd writer")
 
-	return tar.New(a.logger, a.root, a.skipSymlinks).Create(srcs, zw)
+	wBytes, err := tar.New(a.logger, a.root, a.skipSymlinks).Create(srcs, zw)
+	if err != nil {
+		return 0, fmt.Errorf("zstd create archive, %w", err)
+	}
+
+	return wBytes, nil
 }
 
 // Extract reads content from the given archive reader and restores it to the destination, returns written bytes.
 func (a *Archive) Extract(dst string, r io.Reader) (int64, error) {
 	zr, err := zstd.NewReader(r)
 	if err != nil {
-		return 0, err
+		return 0, fmt.Errorf("zstd create extract archive reader, %w", err)
 	}
 
 	defer internal.CloseWithErrLogf(a.logger, zr.IOReadCloser(), "zstd reader")
 
-	return tar.New(a.logger, a.root, a.skipSymlinks).Extract(dst, zr)
+	eBytes, err := tar.New(a.logger, a.root, a.skipSymlinks).Extract(dst, zr)
+	if err != nil {
+		return 0, fmt.Errorf("zstd extract archive, %w", err)
+	}
+
+	return eBytes, nil
 }
diff --git a/archive/zstd/zstd_test.go b/archive/zstd/zstd_test.go
index 22b3a172..b5f0805a 100644
--- a/archive/zstd/zstd_test.go
+++ b/archive/zstd/zstd_test.go
@@ -8,7 +8,7 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 
 	"github.com/meltwater/drone-cache/archive/tar"
 	"github.com/meltwater/drone-cache/test"
diff --git a/cache/cache.go b/cache/cache.go
index e8a18f04..3694d7b8 100644
--- a/cache/cache.go
+++ b/cache/cache.go
@@ -4,8 +4,7 @@ package cache
 import (
 	"time"
 
-	"github.com/go-kit/kit/log"
-
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/archive"
 	"github.com/meltwater/drone-cache/key"
 	"github.com/meltwater/drone-cache/storage"
diff --git a/cache/flusher.go b/cache/flusher.go
index 458c2e0c..f2d4e0bb 100644
--- a/cache/flusher.go
+++ b/cache/flusher.go
@@ -4,11 +4,10 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/storage"
 	"github.com/meltwater/drone-cache/storage/backend"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
 )
 
 type flusher struct {
diff --git a/cache/rebuilder.go b/cache/rebuilder.go
index e655bb9c..45430306 100644
--- a/cache/rebuilder.go
+++ b/cache/rebuilder.go
@@ -8,14 +8,13 @@ import (
 	"sync"
 	"time"
 
+	"github.com/dustin/go-humanize"
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/archive"
 	"github.com/meltwater/drone-cache/internal"
 	"github.com/meltwater/drone-cache/key"
 	"github.com/meltwater/drone-cache/storage"
-
-	"github.com/dustin/go-humanize"
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
 )
 
 type rebuilder struct {
@@ -133,7 +132,7 @@ func (r rebuilder) rebuild(src, dst string) error {
 			level.Error(r.logger).Log("msg", "pr close", "err", err)
 		}
 
-		return err
+		return fmt.Errorf("rebuilder rebuild put file, %w", err)
 	}
 
 	level.Debug(r.logger).Log(
@@ -165,5 +164,5 @@ func (r rebuilder) generateKey(parts ...string) (string, error) {
 		}
 	}
 
-	return "", err
+	return "", fmt.Errorf("rebuilder generate key, %w", err)
 }
diff --git a/cache/restorer.go b/cache/restorer.go
index dc5ed709..bf8552a7 100644
--- a/cache/restorer.go
+++ b/cache/restorer.go
@@ -7,9 +7,8 @@ import (
 	"sync"
 	"time"
 
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/archive"
 	"github.com/meltwater/drone-cache/internal"
 	"github.com/meltwater/drone-cache/key"
@@ -134,5 +133,5 @@ func (r restorer) generateKey(parts ...string) (string, error) {
 		}
 	}
 
-	return "", err
+	return "", fmt.Errorf("restorer generate key, %w", err)
 }
diff --git a/go.mod b/go.mod
index a0407a44..1b2c85ed 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,6 @@ require (
 	github.com/Azure/azure-storage-blob-go v0.15.0
 	github.com/aws/aws-sdk-go v1.44.55
 	github.com/dustin/go-humanize v1.0.0
-	github.com/go-kit/kit v0.12.0
 	github.com/go-kit/log v0.2.1
 	github.com/google/go-cmp v0.5.8
 	github.com/klauspost/compress v1.15.8
@@ -40,7 +39,7 @@ require (
 	github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 // indirect
 	go.opencensus.io v0.23.0 // indirect
 	golang.org/x/net v0.0.0-20220708220712-1185a9018129 // indirect
-	golang.org/x/sys v0.0.0-20220712014510-0a85c31ab51e // indirect
+	golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/xerrors v0.0.0-20220609144429-65e65417b02f // indirect
 	google.golang.org/appengine v1.6.7 // indirect
diff --git a/go.sum b/go.sum
index c30d8f39..7f68ebd1 100644
--- a/go.sum
+++ b/go.sum
@@ -121,8 +121,6 @@ github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeME
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
-github.com/go-kit/kit v0.12.0 h1:e4o3o3IsBfAKQh5Qbbiqyfu97Ku7jrO/JbohvztANh4=
-github.com/go-kit/kit v0.12.0/go.mod h1:lHd+EkCZPIwYItmGDDRdhinkzX2A1sj+M9biaEaizzs=
 github.com/go-kit/log v0.2.1 h1:MRVx0/zhvdseW+Gza6N9rVzU/IVzaeE1SFI4raAhmBU=
 github.com/go-kit/log v0.2.1/go.mod h1:NwTd00d/i8cPZ3xOwwiv2PO5MOcx78fFErGNcVmBjv0=
 github.com/go-logfmt/logfmt v0.5.1 h1:otpy5pqBCBZ1ng9RQ0dPu4PN7ba75Y/aA+UpowDyNVA=
@@ -476,8 +474,8 @@ golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220610221304-9f5ed59c137d/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220615213510-4f61da869c0c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220624220833-87e55d714810/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220712014510-0a85c31ab51e h1:NHvCuwuS43lGnYhten69ZWqi2QOj/CiDNcKbVqwVoew=
-golang.org/x/sys v0.0.0-20220712014510-0a85c31ab51e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 h1:JGgROgKl9N8DuW20oFS5gxc+lE67/N3FcwmBPMe7ArY=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
diff --git a/internal/io.go b/internal/io.go
index 8c4e6b8e..2947161d 100644
--- a/internal/io.go
+++ b/internal/io.go
@@ -58,5 +58,5 @@ func closeIo(closer io.Closer) error {
 		return nil
 	}
 
-	return err
+	return fmt.Errorf("error closing io.Closer: %w", err)
 }
diff --git a/internal/logger.go b/internal/logger.go
index daeab819..c3707c26 100644
--- a/internal/logger.go
+++ b/internal/logger.go
@@ -43,6 +43,7 @@ func NewLogger(logLevel, logFormat, name string) log.Logger {
 
 	logger = level.NewFilter(logger, lvl)
 	logger = log.With(logger, "name", name)
+	logger = log.With(logger, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller)
 
-	return log.With(logger, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller)
+	return logger
 }
diff --git a/internal/plugin/plugin.go b/internal/plugin/plugin.go
index a31600f0..7879d752 100644
--- a/internal/plugin/plugin.go
+++ b/internal/plugin/plugin.go
@@ -7,6 +7,8 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/archive"
 	"github.com/meltwater/drone-cache/cache"
 	"github.com/meltwater/drone-cache/internal/metadata"
@@ -14,9 +16,6 @@ import (
 	keygen "github.com/meltwater/drone-cache/key/generator"
 	"github.com/meltwater/drone-cache/storage"
 	"github.com/meltwater/drone-cache/storage/backend"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
 )
 
 // Error recognized error from plugin.
@@ -42,7 +41,7 @@ func New(logger log.Logger) *Plugin {
 }
 
 // Exec entry point of Plugin, where the magic happens.
-func (p *Plugin) Exec() error { // nolint:funlen
+func (p *Plugin) Exec() error { // nolint: funlen,cyclop
 	cfg := p.Config
 
 	// 1. Check parameters
@@ -125,6 +124,7 @@ func (p *Plugin) Exec() error { // nolint:funlen
 	if cfg.Rebuild {
 		if err := c.Rebuild(p.Config.Mount); err != nil {
 			level.Debug(p.logger).Log("err", fmt.Sprintf("%+v\n", err))
+
 			return Error(fmt.Sprintf("[IMPORTANT] build cache, %+v\n", err))
 		}
 	}
@@ -132,6 +132,7 @@ func (p *Plugin) Exec() error { // nolint:funlen
 	if cfg.Restore {
 		if err := c.Restore(p.Config.Mount); err != nil {
 			level.Debug(p.logger).Log("err", fmt.Sprintf("%+v\n", err))
+
 			return Error(fmt.Sprintf("[IMPORTANT] restore cache, %+v\n", err))
 		}
 	}
diff --git a/internal/plugin/plugin_test.go b/internal/plugin/plugin_test.go
index 6d832a92..0935c245 100644
--- a/internal/plugin/plugin_test.go
+++ b/internal/plugin/plugin_test.go
@@ -20,7 +20,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/session"
 	awss3 "github.com/aws/aws-sdk-go/service/s3"
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 	pkgsftp "github.com/pkg/sftp"
 	"golang.org/x/crypto/ssh"
 	"google.golang.org/api/option"
diff --git a/key/generator/metadata.go b/key/generator/metadata.go
index 48885917..478d5bfa 100644
--- a/key/generator/metadata.go
+++ b/key/generator/metadata.go
@@ -11,13 +11,16 @@ import (
 	"text/template"
 	"time"
 
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/internal"
 	"github.com/meltwater/drone-cache/internal/metadata"
 )
 
+const (
+	EpochNumBase = 10
+)
+
 // Metadata implements a key generator that uses a template engine to generate keys from give metadata.
 type Metadata struct {
 	logger log.Logger
@@ -35,7 +38,7 @@ func NewMetadata(logger log.Logger, tmpl string, data metadata.Metadata) *Metada
 		data:   data,
 		funcMap: template.FuncMap{
 			"checksum": checksumFunc(logger),
-			"epoch":    func() string { return strconv.FormatInt(time.Now().Unix(), 10) },
+			"epoch":    func() string { return strconv.FormatInt(time.Now().Unix(), EpochNumBase) },
 			"arch":     func() string { return runtime.GOARCH },
 			"os":       func() string { return runtime.GOOS },
 		},
@@ -69,13 +72,19 @@ func (g *Metadata) Generate(_ ...string) (string, error) {
 // Check checks if template is parsable.
 func (g *Metadata) Check() error {
 	_, err := g.parseTemplate()
+
 	return err
 }
 
 // Helpers
 
 func (g *Metadata) parseTemplate() (*template.Template, error) {
-	return template.New("cacheKey").Funcs(g.funcMap).Parse(g.tmpl)
+	tmpl, err := template.New("cacheKey").Funcs(g.funcMap).Parse(g.tmpl)
+	if err != nil {
+		return &template.Template{}, fmt.Errorf("parse template failed, %w", err)
+	}
+
+	return tmpl, nil
 }
 
 func checksumFunc(logger log.Logger) func(string) string {
@@ -83,12 +92,14 @@ func checksumFunc(logger log.Logger) func(string) string {
 		path, err := filepath.Abs(filepath.Clean(p))
 		if err != nil {
 			level.Error(logger).Log("cache key template/checksum could not find file")
+
 			return ""
 		}
 
 		f, err := os.Open(path)
 		if err != nil {
 			level.Error(logger).Log("cache key template/checksum could not open file")
+
 			return ""
 		}
 
@@ -97,6 +108,7 @@ func checksumFunc(logger log.Logger) func(string) string {
 		str, err := readerHasher(f)
 		if err != nil {
 			level.Error(logger).Log("cache key template/checksum could not generate hash")
+
 			return ""
 		}
 
diff --git a/key/generator/metadata_test.go b/key/generator/metadata_test.go
index 71a9d60b..9662bc39 100644
--- a/key/generator/metadata_test.go
+++ b/key/generator/metadata_test.go
@@ -4,7 +4,7 @@ import (
 	"testing"
 	"text/template"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/internal/metadata"
 	"github.com/meltwater/drone-cache/test"
 )
diff --git a/main.go b/main.go
index a948836d..5f0251a6 100644
--- a/main.go
+++ b/main.go
@@ -2,9 +2,12 @@ package main
 
 import (
 	"errors"
+	"fmt"
 	stdlog "log"
 	"os"
 
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/archive"
 	"github.com/meltwater/drone-cache/internal"
 	"github.com/meltwater/drone-cache/internal/metadata"
@@ -16,9 +19,6 @@ import (
 	"github.com/meltwater/drone-cache/storage/backend/gcs"
 	"github.com/meltwater/drone-cache/storage/backend/s3"
 	"github.com/meltwater/drone-cache/storage/backend/sftp"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
 	"github.com/urfave/cli/v2"
 )
 
@@ -483,7 +483,7 @@ func main() {
 
 // nolint:funlen
 func run(c *cli.Context) error {
-	var logLevel = c.String("log.level")
+	logLevel := c.String("log.level")
 	if c.Bool("debug") {
 		logLevel = internal.LogLevelDebug
 	}
@@ -599,7 +599,7 @@ func run(c *cli.Context) error {
 		// If it is exit-code enabled, always exit with error.
 		level.Warn(logger).Log("msg", "silent fails disabled, exiting with status code on error")
 
-		return err
+		return fmt.Errorf("status code exit, %w", err)
 	}
 
 	var e plugin.Error
@@ -610,5 +610,5 @@ func run(c *cli.Context) error {
 		return nil
 	}
 
-	return err
+	return fmt.Errorf("uncaught error, %w", err)
 }
diff --git a/storage/backend/azure/azure.go b/storage/backend/azure/azure.go
index 9b53bf59..66289ece 100644
--- a/storage/backend/azure/azure.go
+++ b/storage/backend/azure/azure.go
@@ -9,9 +9,8 @@ import (
 	"net/url"
 
 	"github.com/Azure/azure-storage-blob-go/azblob"
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/internal"
 )
 
@@ -65,6 +64,7 @@ func New(l log.Logger, c Config) (*Backend, error) {
 
 	_, err = containerURL.Create(ctx, azblob.Metadata{}, azblob.PublicAccessNone)
 	if err != nil {
+		// nolint: errorlint
 		ret, ok := err.(azblob.StorageError)
 		if !ok {
 			return nil, fmt.Errorf("azure, unexpected error, %w", err)
@@ -79,7 +79,7 @@ func New(l log.Logger, c Config) (*Backend, error) {
 }
 
 // Get writes downloaded content to the given writer.
-func (b *Backend) Get(ctx context.Context, p string, w io.Writer) (err error) {
+func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 	errCh := make(chan error)
 
 	go func() {
@@ -87,9 +87,11 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) (err error) {
 
 		blobURL := b.containerURL.NewBlockBlobURL(p)
 
+		// nolint: lll
 		resp, err := blobURL.Download(ctx, 0, azblob.CountToEnd, azblob.BlobAccessConditions{}, false, azblob.ClientProvidedKeyOptions{})
 		if err != nil {
 			errCh <- fmt.Errorf("get the object, %w", err)
+
 			return
 		}
 
@@ -106,6 +108,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) (err error) {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
diff --git a/storage/backend/azure/azure_test.go b/storage/backend/azure/azure_test.go
index 7983a35f..50c51cc1 100644
--- a/storage/backend/azure/azure_test.go
+++ b/storage/backend/azure/azure_test.go
@@ -11,7 +11,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/test"
 )
 
diff --git a/storage/backend/backend.go b/storage/backend/backend.go
index 3f6d622a..ebe1b98d 100644
--- a/storage/backend/backend.go
+++ b/storage/backend/backend.go
@@ -7,9 +7,8 @@ import (
 	"io"
 	"time"
 
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/storage/backend/azure"
 	"github.com/meltwater/drone-cache/storage/backend/filesystem"
 	"github.com/meltwater/drone-cache/storage/backend/gcs"
diff --git a/storage/backend/filesystem/filesystem.go b/storage/backend/filesystem/filesystem.go
index 8552f9ee..19debf86 100644
--- a/storage/backend/filesystem/filesystem.go
+++ b/storage/backend/filesystem/filesystem.go
@@ -9,13 +9,12 @@ import (
 	"path/filepath"
 	"strings"
 
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/internal"
 )
 
-const defaultFileMode = 0755
+const defaultFileMode = 0o755
 
 // Backend is an file system implementation of the Backend.
 type Backend struct {
@@ -54,6 +53,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 		rc, err := os.Open(path)
 		if err != nil {
 			errCh <- fmt.Errorf("get the object, %w", err)
+
 			return
 		}
 
@@ -62,6 +62,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 		_, err = io.Copy(w, rc)
 		if err != nil {
 			errCh <- fmt.Errorf("copy the object, %w", err)
+
 			return
 		}
 	}()
@@ -70,6 +71,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
@@ -94,6 +96,7 @@ func (b *Backend) Put(ctx context.Context, p string, r io.Reader) error {
 		w, err := os.Create(path)
 		if err != nil {
 			errCh <- fmt.Errorf("create cache file, %w", err)
+
 			return
 		}
 
@@ -112,6 +115,7 @@ func (b *Backend) Put(ctx context.Context, p string, r io.Reader) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
diff --git a/storage/backend/filesystem/filesystem_test.go b/storage/backend/filesystem/filesystem_test.go
index fec22939..16602e04 100644
--- a/storage/backend/filesystem/filesystem_test.go
+++ b/storage/backend/filesystem/filesystem_test.go
@@ -7,7 +7,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/test"
 )
 
diff --git a/storage/backend/gcs/gcs.go b/storage/backend/gcs/gcs.go
index c3e86f5a..f48257dc 100644
--- a/storage/backend/gcs/gcs.go
+++ b/storage/backend/gcs/gcs.go
@@ -3,16 +3,16 @@ package gcs
 import (
 	"context"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"strings"
 
-	"github.com/meltwater/drone-cache/internal"
-
 	gcstorage "cloud.google.com/go/storage"
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/meltwater/drone-cache/internal"
 	"golang.org/x/oauth2/google"
 	"google.golang.org/api/option"
 )
@@ -80,6 +80,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 		r, err := obj.NewReader(ctx)
 		if err != nil {
 			errCh <- fmt.Errorf("get the object, %w", err)
+
 			return
 		}
 
@@ -95,6 +96,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
@@ -136,6 +138,7 @@ func (b *Backend) Put(ctx context.Context, p string, r io.Reader) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
@@ -160,8 +163,9 @@ func (b *Backend) Exists(ctx context.Context, p string) (bool, error) {
 		}
 
 		attrs, err := obj.Attrs(ctx)
-		if err != nil && err != gcstorage.ErrObjectNotExist {
+		if err != nil && !errors.Is(err, gcstorage.ErrObjectNotExist) {
 			resCh <- &result{err: fmt.Errorf("get the object attrs, %w", err)}
+
 			return
 		}
 
@@ -172,6 +176,7 @@ func (b *Backend) Exists(ctx context.Context, p string) (bool, error) {
 	case res := <-resCh:
 		return res.val, res.err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return false, ctx.Err()
 	}
 }
@@ -181,12 +186,14 @@ func (b *Backend) Exists(ctx context.Context, p string) (bool, error) {
 func setAuthenticationMethod(l log.Logger, c Config, opts []option.ClientOption) []option.ClientOption {
 	if c.APIKey != "" {
 		opts = append(opts, option.WithAPIKey(c.APIKey))
+
 		return opts
 	}
 
 	creds, err := credentials(l, c)
 	if err == nil {
 		opts = append(opts, option.WithCredentials(creds))
+
 		return opts
 	}
 
@@ -211,7 +218,7 @@ func credentials(l log.Logger, c Config) (*google.Credentials, error) {
 
 	creds, err = google.FindDefaultCredentials(ctx, gcstorage.ScopeFullControl)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("gcs credentials not found, %w", err)
 	}
 
 	return creds, nil
diff --git a/storage/backend/gcs/gcs_test.go b/storage/backend/gcs/gcs_test.go
index a7b02e0c..aec9c7e7 100644
--- a/storage/backend/gcs/gcs_test.go
+++ b/storage/backend/gcs/gcs_test.go
@@ -14,7 +14,7 @@ import (
 	"time"
 
 	gcstorage "cloud.google.com/go/storage"
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/test"
 	"google.golang.org/api/option"
 )
diff --git a/storage/backend/s3/s3.go b/storage/backend/s3/s3.go
index 7ed3c53e..6d5140ed 100644
--- a/storage/backend/s3/s3.go
+++ b/storage/backend/s3/s3.go
@@ -13,9 +13,8 @@ import (
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/aws/aws-sdk-go/service/s3/s3manager"
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/meltwater/drone-cache/internal"
 )
 
@@ -98,6 +97,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 		out, err := b.client.GetObjectWithContext(ctx, in)
 		if err != nil {
 			errCh <- fmt.Errorf("get the object, %w", err)
+
 			return
 		}
 
@@ -113,6 +113,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
@@ -149,6 +150,7 @@ func (b *Backend) Exists(ctx context.Context, p string) (bool, error) {
 
 	out, err := b.client.HeadObjectWithContext(ctx, in)
 	if err != nil {
+		// nolint: errorlint
 		if awsErr, ok := err.(awserr.Error); ok && awsErr.Code() == s3.ErrCodeNoSuchKey || awsErr.Code() == "NotFound" {
 			return false, nil
 		}
@@ -169,7 +171,6 @@ func assumeRole(l log.Logger, c *aws.Config, roleArn string) credentials.Value {
 		DisableSSL:                    c.DisableSSL,
 		CredentialsChainVerboseErrors: aws.Bool(true),
 	})
-
 	if err != nil {
 		level.Error(l).Log("msg", "s3 backend", "assume-role", err.Error())
 	}
@@ -177,7 +178,6 @@ func assumeRole(l log.Logger, c *aws.Config, roleArn string) credentials.Value {
 	creds, err := stscreds.NewCredentials(sess, roleArn, func(p *stscreds.AssumeRoleProvider) {
 		p.RoleSessionName = "drone-cache"
 	}).Get()
-
 	if err != nil {
 		level.Error(l).Log("msg", "s3 backend", "assume-role", err.Error())
 	}
diff --git a/storage/backend/s3/s3_test.go b/storage/backend/s3/s3_test.go
index b2e183e1..668078e8 100644
--- a/storage/backend/s3/s3_test.go
+++ b/storage/backend/s3/s3_test.go
@@ -14,7 +14,7 @@ import (
 	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3"
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 
 	"github.com/meltwater/drone-cache/test"
 )
diff --git a/storage/backend/sftp/sftp.go b/storage/backend/sftp/sftp.go
index 48c38c31..d0fd3559 100644
--- a/storage/backend/sftp/sftp.go
+++ b/storage/backend/sftp/sftp.go
@@ -9,12 +9,11 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/meltwater/drone-cache/internal"
 	"github.com/pkg/sftp"
 	"golang.org/x/crypto/ssh"
-
-	"github.com/meltwater/drone-cache/internal"
 )
 
 // Backend implements storage.Backend for sFTP.
@@ -46,6 +45,7 @@ func New(l log.Logger, c Config) (*Backend, error) {
 	client, err := sftp.NewClient(sshClient)
 	if err != nil {
 		sshClient.Close()
+
 		return nil, fmt.Errorf("unable to connect to ssh with sftp protocol, %w", err)
 	}
 
@@ -73,6 +73,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 		rc, err := b.client.Open(path)
 		if err != nil {
 			errCh <- fmt.Errorf("get the object, %w", err)
+
 			return
 		}
 
@@ -88,6 +89,7 @@ func (b *Backend) Get(ctx context.Context, p string, w io.Writer) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
@@ -104,12 +106,14 @@ func (b *Backend) Put(ctx context.Context, p string, r io.Reader) error {
 		dir := filepath.Dir(path)
 		if err := b.client.MkdirAll(dir); err != nil {
 			errCh <- fmt.Errorf("create directory, %w", err)
+
 			return
 		}
 
 		w, err := b.client.Create(path)
 		if err != nil {
 			errCh <- fmt.Errorf("create cache file, %w", err)
+
 			return
 		}
 
@@ -128,6 +132,7 @@ func (b *Backend) Put(ctx context.Context, p string, r io.Reader) error {
 	case err := <-errCh:
 		return err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return ctx.Err()
 	}
 }
@@ -152,6 +157,7 @@ func (b *Backend) Exists(ctx context.Context, p string) (bool, error) {
 		_, err := b.client.Stat(path)
 		if err != nil && !os.IsNotExist(err) {
 			resCh <- &result{err: fmt.Errorf("check the object exists, %w", err)}
+
 			return
 		}
 		resCh <- &result{val: err == nil}
@@ -161,6 +167,7 @@ func (b *Backend) Exists(ctx context.Context, p string) (bool, error) {
 	case res := <-resCh:
 		return res.val, res.err
 	case <-ctx.Done():
+		// nolint: wrapcheck
 		return false, ctx.Err()
 	}
 }
@@ -173,6 +180,7 @@ func authMethod(c Config) ([]ssh.AuthMethod, error) {
 		return []ssh.AuthMethod{ssh.Password(c.Auth.Password)}, nil
 	case SSHAuthMethodPublicKeyFile:
 		pkAuthMethod, err := readPublicKeyFile(c.Auth.PublicKeyFile)
+
 		return []ssh.AuthMethod{pkAuthMethod}, err
 	default:
 		return nil, errors.New("unknown ssh method (PASSWORD, PUBLIC_KEY_FILE)")
diff --git a/storage/backend/sftp/sftp_test.go b/storage/backend/sftp/sftp_test.go
index cb4a1cf2..6f6b16d0 100644
--- a/storage/backend/sftp/sftp_test.go
+++ b/storage/backend/sftp/sftp_test.go
@@ -12,7 +12,7 @@ import (
 
 	"github.com/meltwater/drone-cache/test"
 
-	"github.com/go-kit/kit/log"
+	"github.com/go-kit/log"
 )
 
 const (
diff --git a/storage/storage.go b/storage/storage.go
index 31d2ca81..358697f3 100644
--- a/storage/storage.go
+++ b/storage/storage.go
@@ -2,12 +2,12 @@ package storage
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"time"
 
+	"github.com/go-kit/log"
 	"github.com/meltwater/drone-cache/storage/backend"
-
-	"github.com/go-kit/kit/log"
 )
 
 const DefaultOperationTimeout = 3 * time.Minute
@@ -48,7 +48,11 @@ func (s *storage) Get(p string, w io.Writer) error {
 	ctx, cancel := context.WithTimeout(context.Background(), s.timeout)
 	defer cancel()
 
-	return s.b.Get(ctx, p, w)
+	if err := s.b.Get(ctx, p, w); err != nil {
+		return fmt.Errorf("storage backend get failure, %w", err)
+	}
+
+	return nil
 }
 
 // Put writes contents of io.Reader to remote storage at given key location.
@@ -56,7 +60,11 @@ func (s *storage) Put(p string, r io.Reader) error {
 	ctx, cancel := context.WithTimeout(context.Background(), s.timeout)
 	defer cancel()
 
-	return s.b.Put(ctx, p, r)
+	if err := s.b.Put(ctx, p, r); err != nil {
+		return fmt.Errorf("storage backend put failure, %w", err)
+	}
+
+	return nil
 }
 
 // Exists checks if object with given key exists in remote storage.
@@ -64,7 +72,12 @@ func (s *storage) Exists(p string) (bool, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), s.timeout)
 	defer cancel()
 
-	return s.b.Exists(ctx, p)
+	ret, err := s.b.Exists(ctx, p)
+	if err != nil {
+		return ret, fmt.Errorf("storage backend exists failure, %w", err)
+	}
+
+	return ret, nil
 }
 
 // List lists contents of the given directory by given key from remote storage.