command/fix: boilerplate for the fix command

command/fix/command.go

+package fix
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"github.com/mitchellh/packer/packer"
+	"os"
+	"strings"
+)
+
+type Command byte
+
+func (Command) Help() string {
+	return strings.TrimSpace(helpString)
+}
+
+func (c Command) Run(env packer.Environment, args []string) int {
+	cmdFlags := flag.NewFlagSet("fix", flag.ContinueOnError)
+	cmdFlags.Usage = func() { env.Ui().Say(c.Help()) }
+	if err := cmdFlags.Parse(args); err != nil {
+		return 1
+	}
+
+	args = cmdFlags.Args()
+	if len(args) != 1 {
+		cmdFlags.Usage()
+		return 1
+	}
+
+	// Read the file for decoding
+	tplF, err := os.Open(args[0])
+	if err != nil {
+		env.Ui().Error(fmt.Sprintf("Error opening template: %s", err))
+		return 1
+	}
+	defer tplF.Close()
+
+	// Decode the JSON into a generic map structure
+	var templateData map[string]interface{}
+	decoder := json.NewDecoder(tplF)
+	if err := decoder.Decode(&templateData); err != nil {
+		env.Ui().Error(fmt.Sprintf("Error parsing template: %s", err))
+		return 1
+	}
+
+	// Close the file since we're done with that
+	tplF.Close()
+
+	return 0
+}
+
+func (c Command) Synopsis() string {
+	return "fixes templates from old versions of packer"
+}

command/fix/command_test.go

+package fix
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func TestCommand_Impl(t *testing.T) {
+	var raw interface{}
+	raw = new(Command)
+	if _, ok := raw.(packer.Command); !ok {
+		t.Fatalf("must be a Command")
+	}
+}

command/fix/help.go

+package fix
+
+const helpString = `
+Usage: packer fix [options] TEMPLATE
+
+  Reads the JSON template and attempts to fix known backwards
+  incompatibilities. The fixed template will be outputted to standard out.
+
+  If the template cannot be fixed due to an error, the command will exit
+  with a non-zero exit status. Error messages will appear on standard error.
+
+Options:
+
+  -verbose        Output each fix to standard error
+`

config.go

@@ -27,6 +27,7 @@ const defaultConfig = `
 
 	"commands": {
 		"build": "packer-command-build",
+		"fix": "packer-command-fix",
 		"validate": "packer-command-validate"
 	},
 

plugin/command-fix/main.go

+package main
+
+import (
+	"github.com/mitchellh/packer/command/fix"
+	"github.com/mitchellh/packer/packer/plugin"
+)
+
+func main() {
+	plugin.ServeCommand(new(fix.Command))
+}