fix(kubernetes): correct handling of kubectl stderr (#61)

Always shows stderr from kubectl in case an error occurs

Author: sh0rez

pkg/kubernetes/errors.go

@@ -3,11 +3,12 @@ package kubernetes
 import "fmt"
 
 type ErrorNotFound struct {
-	resource string
+	name string
+	kind string
 }
 
 func (e ErrorNotFound) Error() string {
-	return fmt.Sprintf(`error from server (NotFound): secrets "%s" not found`, e.resource)
+	return fmt.Sprintf(`error from server (NotFound): %s "%s" not found`, e.kind, e.name)
 }
 
 type ErrorMissingConfig struct {

pkg/kubernetes/kubectl.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"regexp"
 	"strings"
 
 	"github.com/Masterminds/semver"
@@ -39,6 +40,7 @@ func (k Kubectl) Version() (client, server semver.Version, err error) {
 	)
 	var buf bytes.Buffer
 	cmd.Stdout = &buf
+	cmd.Stderr = os.Stderr
 	if err := cmd.Run(); err != nil {
 		return zero, zero, err
 	}
@@ -57,6 +59,7 @@ func (k *Kubectl) setupContext() error {
 	cmd := exec.Command("kubectl", "config", "view", "-o", "json")
 	cfgJSON := bytes.Buffer{}
 	cmd.Stdout = &cfgJSON
+	cmd.Stderr = os.Stderr
 	if err := cmd.Run(); err != nil {
 		return err
 	}
@@ -115,9 +118,9 @@ func (k Kubectl) Get(namespace, kind, name string) (map[string]interface{}, erro
 	cmd.Stderr = &serr
 	if err := cmd.Run(); err != nil {
 		if strings.HasPrefix(serr.String(), "Error from server (NotFound)") {
-			return nil, ErrorNotFound{name}
+			return nil, ErrorNotFound{kind, name}
 		}
-		fmt.Println(serr.String())
+		fmt.Print(serr.String())
 		return nil, err
 	}
 	var obj map[string]interface{}
@@ -196,6 +199,7 @@ func (k Kubectl) Diff(yaml string) (*string, error) {
 	cmd := exec.Command("kubectl", argv...)
 	raw := bytes.Buffer{}
 	cmd.Stdout = &raw
+	cmd.Stderr = FilteredErr{regexp.MustCompile(`exit status \d`)}
 
 	stdin, err := cmd.StdinPipe()
 	if err != nil {

pkg/kubernetes/util.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 )
 
 func diff(name, is, should string) (string, error) {
@@ -44,3 +45,16 @@ func diff(name, is, should string) (string, error) {
 
 	return out, nil
 }
+
+// FilteredErr is a filtered Stderr. If one of the regular expressions match, the current input is discarded.
+type FilteredErr []*regexp.Regexp
+
+func (r FilteredErr) Write(p []byte) (n int, err error) {
+	for _, re := range r {
+		if re.Match(p) {
+			// silently discard
+			return len(p), nil
+		}
+	}
+	return os.Stderr.Write(p)
+}