Improve error output

* initial debug output when using `helm --debug`
* output stderr from child commands in case of an error
* Remove spurios output of error to stdout

Author: databus23

cmd/helm3.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"os/exec"
 	"strconv"
+	"strings"
 )
 
 func getRelease(release, namespace string) ([]byte, error) {
@@ -13,7 +14,7 @@ func getRelease(release, namespace string) ([]byte, error) {
 		args = append(args, "--namespace", namespace)
 	}
 	cmd := exec.Command(os.Getenv("HELM_BIN"), args...)
-	return cmd.Output()
+	return outputWithRichError(cmd)
 }
 
 func getHooks(release, namespace string) ([]byte, error) {
@@ -22,7 +23,7 @@ func getHooks(release, namespace string) ([]byte, error) {
 		args = append(args, "--namespace", namespace)
 	}
 	cmd := exec.Command(os.Getenv("HELM_BIN"), args...)
-	return cmd.Output()
+	return outputWithRichError(cmd)
 }
 
 func getRevision(release string, revision int, namespace string) ([]byte, error) {
@@ -31,7 +32,7 @@ func getRevision(release string, revision int, namespace string) ([]byte, error)
 		args = append(args, "--namespace", namespace)
 	}
 	cmd := exec.Command(os.Getenv("HELM_BIN"), args...)
-	return cmd.Output()
+	return outputWithRichError(cmd)
 }
 
 func getChart(release, namespace string) (string, error) {
@@ -40,7 +41,7 @@ func getChart(release, namespace string) (string, error) {
 		args = append(args, "--namespace", namespace)
 	}
 	cmd := exec.Command(os.Getenv("HELM_BIN"), args...)
-	out, err := cmd.Output()
+	out, err := outputWithRichError(cmd)
 	if err != nil {
 		return "", err
 	}
@@ -87,11 +88,12 @@ func (d *diffCmd) template() ([]byte, error) {
 	args := []string{"template", d.release, d.chart}
 	args = append(args, flags...)
 	cmd := exec.Command(os.Getenv("HELM_BIN"), args...)
-	return cmd.Output()
+	return outputWithRichError(cmd)
 }
 
 func (d *diffCmd) existingValues(f *os.File) error {
 	cmd := exec.Command(os.Getenv("HELM_BIN"), "get", "values", d.release, "--all")
+	DebugPrint("Executing %s", strings.Join(cmd.Args, " "))
 	defer f.Close()
 	cmd.Stdout = f
 	return cmd.Run()

cmd/helpers.go

@@ -3,7 +3,9 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
+	"strings"
 
 	flag "github.com/spf13/pflag"
 	"k8s.io/client-go/util/homedir"
@@ -31,6 +33,15 @@ func isHelm3() bool {
 	return os.Getenv("TILLER_HOST") == ""
 }
 
+func isDebug() bool {
+	return os.Getenv("HELM_DEBUG") == "true"
+}
+func DebugPrint(format string, a ...interface{}) {
+	if isDebug() {
+		fmt.Printf(format+"\n", a...)
+	}
+}
+
 func addCommonCmdOptions(f *flag.FlagSet) {
 	settings.AddFlagsTLS(f)
 	settings.InitTLS(f)
@@ -71,3 +82,12 @@ func expandTLSPaths() {
 	settings.TLSCertFile = os.ExpandEnv(settings.TLSCertFile)
 	settings.TLSKeyFile = os.ExpandEnv(settings.TLSKeyFile)
 }
+
+func outputWithRichError(cmd *exec.Cmd) ([]byte, error) {
+	DebugPrint("Executing %s", strings.Join(cmd.Args, " "))
+	output, err := cmd.Output()
+	if exitError, ok := err.(*exec.ExitError); ok {
+		return output, fmt.Errorf("%s: %s", exitError.Error(), string(exitError.Stderr))
+	}
+	return output, err
+}

cmd/upgrade.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"os/exec"
 	"strings"
 
 	"github.com/spf13/cobra"
@@ -111,7 +110,7 @@ func (d *diffCmd) runHelm3() error {
 	releaseManifest, err := getRelease(d.release, d.namespace)
 
 	var newInstall bool
-	if err != nil && strings.Contains(string(err.(*exec.ExitError).Stderr), "release: not found") {
+	if err != nil && strings.Contains(err.Error(), "release: not found") {
 		if d.allowUnreleased {
 			fmt.Printf("********************\n\n\tRelease was not present in Helm.  Diff will show entire contents as new.\n\n********************\n")
 			err = nil
@@ -122,12 +121,12 @@ func (d *diffCmd) runHelm3() error {
 
 	}
 	if err != nil {
-		return err
+		return fmt.Errorf("Failed to get release %s in namespace %s: %s", d.release, d.namespace, err)
 	}
 
 	installManifest, err := d.template()
 	if err != nil {
-		return err
+		return fmt.Errorf("Failed to render chart: %s", err)
 	}
 
 	currentSpecs := make(map[string]*manifest.MappingResult)

main.go

@@ -1,15 +1,13 @@
 package main
 
 import (
-	"fmt"
 	"os"
 
 	"github.com/databus23/helm-diff/cmd"
 )
 
 func main() {
 	if err := cmd.New().Execute(); err != nil {
-		fmt.Println(err)
 		switch e := err.(type) {
 		case cmd.Error:
 			os.Exit(e.Code)