feat: Add the --format option to the finch version command (#926)

Currently, the `finch version` command does not support the `--format`
option.

However, a feature request has been submitted in the following issue to
add the `--format` option to the `finch version` command.

- #199

Therefore, this fix introduces the `--format` option to the `finch
version` command.

Issue #, if available: #199 

*Description of changes:* Details are described in this commit message.

*Testing done:* Yes



- [x] I've reviewed the guidance in CONTRIBUTING.md


#### License Acceptance

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Signed-off-by: Hayato Kiwata <[email protected]>

cmd/finch/version.go

@@ -4,19 +4,48 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"text/template"
 
 	"github.com/spf13/cobra"
 
 	"github.com/runfinch/finch/pkg/command"
 	"github.com/runfinch/finch/pkg/flog"
 	"github.com/runfinch/finch/pkg/lima"
+	"github.com/runfinch/finch/pkg/templates"
 	"github.com/runfinch/finch/pkg/version"
 )
 
+const defaultVersionTemplate = `{{with .Client -}}
+Client:
+ Version:	{{.Version}}
+ GitCommit:	{{.GitCommit}}
+ {{with .NerdctlClient -}}
+ OS/Arch:	{{.Os}}/{{.Arch}}
+ nerdctl:
+  Version:	{{.Version}}
+  GitCommit:	{{.GitCommit}}
+ {{- range $component := .Components}}
+ {{$component.Name}}:
+  Version:	{{.Version}}
+  GitCommit:	{{.Details.GitCommit}}
+ {{- end}}
+ {{- end}}
+{{- end}}
+
+{{with .Server -}}
+Server:
+{{- range $component := .Components}}
+ {{$component.Name}}:
+  Version:	{{.Version}}
+  GitCommit:	{{.Details.GitCommit}}
+{{- end}}
+{{- end}}`
+
 func newVersionCommand(limaCmdCreator command.LimaCmdCreator, logger flog.Logger, stdOut io.Writer) *cobra.Command {
 	versionCommand := &cobra.Command{
 		Use:   "version",
@@ -25,6 +54,8 @@ func newVersionCommand(limaCmdCreator command.LimaCmdCreator, logger flog.Logger
 		RunE:  newVersionAction(limaCmdCreator, logger, stdOut).runAdapter,
 	}
 
+	versionCommand.Flags().StringP("format", "f", "", "Format the output using the given Go template, e.g, '{{json .}}'")
+
 	return versionCommand
 }
 
@@ -40,6 +71,19 @@ type NerdctlVersionOutput struct {
 	Server NerdctlServerOutput `json:"Server"`
 }
 
+// FinchVersionOutput captures the finch version.
+type FinchVersionOutput struct {
+	Client ClientVersionOutput `json:"Client"`
+	Server NerdctlServerOutput `json:"Server"`
+}
+
+// ClientVersionOutput captures the commit ID for finch and the nerdctl Client output.
+type ClientVersionOutput struct {
+	Version       string              `json:"Version"`
+	GitCommit     string              `json:"GitCommit"`
+	NerdctlClient NerdctlClientOutput `json:"NerdctlClient"`
+}
+
 // NerdctlClientOutput captures the nerdctl Client output.
 type NerdctlClientOutput struct {
 	Version    string                    `json:"Version"`
@@ -50,11 +94,6 @@ type NerdctlClientOutput struct {
 	Components []NerdctlComponentsOutput `json:"Components"`
 }
 
-// NerdctlServerOutput captures the nerdctl Server output.
-type NerdctlServerOutput struct {
-	Components []NerdctlComponentsOutput `json:"Components"`
-}
-
 // NerdctlComponentsOutput captures the nerdctl components output.
 type NerdctlComponentsOutput struct {
 	Name    string `json:"Name"`
@@ -64,23 +103,75 @@ type NerdctlComponentsOutput struct {
 	}
 }
 
+// NerdctlServerOutput captures the nerdctl Server output.
+type NerdctlServerOutput struct {
+	Components []NerdctlComponentsOutput `json:"Components"`
+}
+
 func newVersionAction(creator command.LimaCmdCreator, logger flog.Logger, stdOut io.Writer) *versionAction {
 	return &versionAction{creator: creator, logger: logger, stdOut: stdOut}
 }
 
-func (va *versionAction) runAdapter(_ *cobra.Command, _ []string) error {
-	return va.run()
+func (va *versionAction) runAdapter(cmd *cobra.Command, _ []string) error {
+	format, err := cmd.Flags().GetString("format")
+	if err != nil {
+		return err
+	}
+
+	return va.run(format)
 }
 
-func (va *versionAction) run() error {
-	if err := va.printVersion(); err != nil {
+func (va *versionAction) run(format string) error {
+	if err := va.printVersion(format); err != nil {
 		fmt.Fprintf(va.stdOut, "Finch version:\t%s\n", version.Version)
 		return err
 	}
 	return nil
 }
 
-func (va *versionAction) printVersion() error {
+func newVersionTemplate(templateFormat string) (*template.Template, error) {
+	switch templateFormat {
+	case "":
+		templateFormat = defaultVersionTemplate
+	case templates.JSONFormatKey:
+		templateFormat = templates.JSONFormat
+	}
+
+	tmpl := templates.New("version")
+	tmpl, err := tmpl.Parse(templateFormat)
+	if err != nil {
+		return nil, err
+	}
+
+	return tmpl, nil
+}
+
+func createFinchVersionOutput(nerdctlVersion NerdctlVersionOutput) FinchVersionOutput {
+	var finchVersionOutput FinchVersionOutput
+
+	finchVersionOutput.Client.Version = version.Version
+	finchVersionOutput.Client.GitCommit = version.GitCommit
+	finchVersionOutput.Client.NerdctlClient = nerdctlVersion.Client
+	finchVersionOutput.Server = nerdctlVersion.Server
+
+	return finchVersionOutput
+}
+
+func (va *versionAction) showVersionMessage(tmpl *template.Template, nerdctlVersion NerdctlVersionOutput) error {
+	var b bytes.Buffer
+
+	finchVersionOutput := createFinchVersionOutput(nerdctlVersion)
+	if err := tmpl.Execute(&b, finchVersionOutput); err != nil {
+		return err
+	}
+	if _, err := fmt.Fprintln(va.stdOut, b.String()); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (va *versionAction) printVersion(format string) error {
 	status, err := lima.GetVMStatus(va.creator, va.logger, limaInstanceName)
 	if err != nil {
 		return fmt.Errorf("failed to get VM status: %w", err)
@@ -102,24 +193,13 @@ func (va *versionAction) printVersion() error {
 		return fmt.Errorf("failed to JSON-unmarshal the nerdctl version output: %w", err)
 	}
 
-	fmt.Fprintf(va.stdOut, "Client:\n")
-	fmt.Fprintf(va.stdOut, " Version:\t%s\n", version.Version)
-	fmt.Fprintf(va.stdOut, " OS/Arch:\t%s/%s\n", nerdctlVersion.Client.Os, nerdctlVersion.Client.Arch)
-	fmt.Fprintf(va.stdOut, " GitCommit:\t%s\n", version.GitCommit)
-	fmt.Fprintf(va.stdOut, " nerdctl:\n")
-	fmt.Fprintf(va.stdOut, "  Version:\t%s\n", nerdctlVersion.Client.Version)
-	fmt.Fprintf(va.stdOut, "  GitCommit:\t%s\n", nerdctlVersion.Client.GitCommit)
-	for _, compo := range nerdctlVersion.Client.Components {
-		fmt.Fprintf(va.stdOut, " %s:\n", compo.Name)
-		fmt.Fprintf(va.stdOut, "  Version:\t%s\n", compo.Version)
-		fmt.Fprintf(va.stdOut, "  GitCommit:\t%s\n", compo.Details.GitCommit)
+	tmpl, err := newVersionTemplate(format)
+	if err != nil {
+		return err
 	}
-	fmt.Fprintf(va.stdOut, "\n")
-	fmt.Fprintf(va.stdOut, "Server:\n")
-	for _, compo := range nerdctlVersion.Server.Components {
-		fmt.Fprintf(va.stdOut, " %s:\n", compo.Name)
-		fmt.Fprintf(va.stdOut, "  Version:\t%s\n", compo.Version)
-		fmt.Fprintf(va.stdOut, "  GitCommit:\t%s\n", compo.Details.GitCommit)
+	err = va.showVersionMessage(tmpl, nerdctlVersion)
+	if err != nil {
+		return err
 	}
 
 	return nil