add example in readme file, and improve logging

README.md

@@ -51,6 +51,14 @@ jobs:
 
 - [bash](https://github.com/ahmetb/kubectx/blob/master/.github/workflows/release.yml)
 
+# Testing the template file
+
+You can test the template file rendering before check-in to the repo by running following command
+```bash
+$ docker run -v /path/to/your/template-file.yaml:/tmp/template-file.yaml rajatjindal/krew-release-bot:v0.0.32 \
+  krew-release-bot template --tag <tag-name> --template-file /tmp/template-file.yaml
+```
+
 # Limitations of krew-release-bot
 - only works for repos hosted on github right now
 - only supports one plugin per git repo right now

cmd/action/template.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/rajatjindal/krew-release-bot/pkg/source"
 	"github.com/sirupsen/logrus"
@@ -17,8 +18,8 @@ var (
 func init() {
 	rootCmd.AddCommand(templateCmd)
 
-	templateCmd.Flags().StringVar(&tagName, "tag-name", "", "tag name to use for templating")
-	templateCmd.MarkFlagRequired("tag-name")
+	templateCmd.Flags().StringVar(&tagName, "tag", "", "tag name to use for templating")
+	templateCmd.MarkFlagRequired("tag")
 
 	templateCmd.Flags().StringVar(&templateFile, "template-file", ".krew.yaml", "template file to use for templating")
 	templateCmd.MarkFlagRequired("template-file")
@@ -39,10 +40,16 @@ var templateCmd = &cobra.Command{
 		}
 
 		_, spec, err := source.ProcessTemplate(templateFile, releaseRequest)
-		if err != nil {
-			logrus.Fatal(err)
+		if err == nil {
+			fmt.Println(string(spec))
+			os.Exit(0)
 		}
 
-		fmt.Println(string(spec))
+		if invalidSpecError, ok := err.(source.InvalidPluginSpecError); ok {
+			fmt.Println(invalidSpecError.Spec)
+			logrus.Fatal(invalidSpecError.Error())
+		}
+
+		logrus.Fatal(err)
 	},
 }

go.sum

@@ -217,6 +217,7 @@ gopkg.in/yaml.v2 v2.2.7/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 k8s.io/apimachinery v0.0.0-20190717022731-0bb8574e0887/go.mod h1:sBJWIJZfxLhp7mRsRyuAE/NfKTr3kXGR1iaqg8O0gJo=
 k8s.io/apimachinery v0.17.0 h1:xRBnuie9rXcPxUkDizUsGvPf1cnlZCFu210op7J7LJo=
 k8s.io/apimachinery v0.17.0/go.mod h1:b9qmWdKlLuU9EBh+06BtLcSf/Mu89rWL33naRxs1uZg=
+k8s.io/apimachinery v0.17.2 h1:hwDQQFbdRlpnnsR64Asdi55GyCaIP/3WQpMmbNBeWr4=
 k8s.io/client-go v7.0.0+incompatible/go.mod h1:7vJpHMYJwNQCWgzmNV+VYUl1zCObLyodBc8nIyt8L5s=
 k8s.io/gengo v0.0.0-20190128074634-0689ccc1d7d6/go.mod h1:ezvh/TsK7cY6rbqRK0oQQ8IAqLxYwwyPxAX1Pzy0ii0=
 k8s.io/klog v0.0.0-20181102134211-b9b56d5dfc92/go.mod h1:Gq+BEi5rUBO/HRz0bTSXDUcqjScdoY3a9IHpCEIOOfk=

pkg/source/template.go

@@ -10,6 +10,16 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+//InvalidPluginSpecError is invalid plugin spec error
+type InvalidPluginSpecError struct {
+	Spec string
+	err  string
+}
+
+func (i InvalidPluginSpecError) Error() string {
+	return i.err
+}
+
 //ProcessTemplate process the .krew.yaml template for the release request
 func ProcessTemplate(templateFile string, values interface{}) (string, []byte, error) {
 	spec, err := RenderTemplate(templateFile, values)
@@ -19,7 +29,10 @@ func ProcessTemplate(templateFile string, values interface{}) (string, []byte, e
 
 	pluginName, err := krew.GetPluginName(spec)
 	if err != nil {
-		return "", nil, fmt.Errorf("failed to get plugin name from processed template.\nerr: %s\n\n\n%s", err.Error(), string(spec))
+		return "", nil, InvalidPluginSpecError{
+			err:  fmt.Sprintf("failed to get plugin name from processed template.\nerr: %s", err.Error()),
+			Spec: string(spec),
+		}
 	}
 
 	return pluginName, spec, nil