command/validate: validates templates

command/validate/commang.go

+package validate
+
+import (
+	"flag"
+	"fmt"
+	"github.com/mitchellh/packer/packer"
+	"io/ioutil"
+	"log"
+	"strings"
+)
+
+type Command byte
+
+func (Command) Help() string {
+	return strings.TrimSpace(helpString)
+}
+
+func (c Command) Run(env packer.Environment, args []string) int {
+	var cfgSyntaxOnly bool
+
+	cmdFlags := flag.NewFlagSet("validate", flag.ContinueOnError)
+	cmdFlags.Usage = func() { env.Ui().Say(c.Help()) }
+	cmdFlags.BoolVar(&cfgSyntaxOnly, "syntax-only", false, "check syntax only")
+	if err := cmdFlags.Parse(args); err != nil {
+		return 1
+	}
+
+	args = cmdFlags.Args()
+	if len(args) != 1 {
+		cmdFlags.Usage()
+		return 1
+	}
+
+	// Read the file into a byte array so that we can parse the template
+	log.Printf("Reading template: %s", args[0])
+	tplData, err := ioutil.ReadFile(args[0])
+	if err != nil {
+		env.Ui().Error(fmt.Sprintf("Failed to read template file: %s", err))
+		return 1
+	}
+
+	// Parse the template into a machine-usable format
+	log.Println("Parsing template...")
+	tpl, err := packer.ParseTemplate(tplData)
+	if err != nil {
+		env.Ui().Error(fmt.Sprintf("Failed to parse template: %s", err))
+		return 1
+	}
+
+	if cfgSyntaxOnly {
+		env.Ui().Say("Syntax-only check passed. Everything looks okay.")
+		return 0
+	}
+
+	errs := make([]error, 0)
+
+	// The component finder for our builds
+	components := &packer.ComponentFinder{
+		Builder:     env.Builder,
+		Hook:        env.Hook,
+		Provisioner: env.Provisioner,
+	}
+
+	// Otherwise, get all the builds
+	buildNames := tpl.BuildNames()
+	builds := make([]packer.Build, len(buildNames))
+	for i, buildName := range buildNames {
+		var err error
+		builds[i], err = tpl.Build(buildName, components)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("Build '%s': %s", buildName, err))
+		}
+	}
+
+	if len(errs) > 0 {
+		err = &packer.MultiError{errs}
+		env.Ui().Error(fmt.Sprintf("Template validation failed. %s", err))
+		return 1
+	}
+
+	env.Ui().Say("Template validated successfully.")
+	return 0
+}
+
+func (Command) Synopsis() string {
+	return "check that a template is valid"
+}

command/validate/help.go

+package validate
+
+const helpString = `
+Usage: packer validate TEMPLATE
+
+  Checks the template is valid by parsing the template and also
+  checking the configuration with the various builders, provisioners, etc.
+
+  If it is not valid, the errors will be shown and the command will exit
+  with a non-zero exit status. If it is valid, it will exit with a zero
+  exit status.
+
+Options:
+
+  -syntax-only        Only check syntax. Do not verify config of the template.
+`

config.go

@@ -23,7 +23,8 @@ const defaultConfig = `
 	},
 
 	"commands": {
-		"build": "packer-command-build"
+		"build": "packer-command-build",
+		"validate": "packer-command-validate"
 	},
 
 	"provisioners": {

plugin/command-validate/main.go

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