packer: validate minimum version [GH-2310]

command/meta.go

@@ -28,6 +28,7 @@ type Meta struct {
 	CoreConfig *packer.CoreConfig
 	Cache      packer.Cache
 	Ui         packer.Ui
+	Version    string
 
 	// These are set by command-line flags
 	flagBuildExcept []string
@@ -42,6 +43,7 @@ func (m *Meta) Core(tpl *template.Template) (*packer.Core, error) {
 	config := *m.CoreConfig
 	config.Template = tpl
 	config.Variables = m.flagVars
+	config.Version = m.Version
 
 	// Init the core
 	core, err := packer.NewCore(&config)

main.go

@@ -168,6 +168,7 @@ func wrappedMain() int {
 				PostProcessor: config.LoadPostProcessor,
 				Provisioner:   config.LoadProvisioner,
 			},
+			Version: Version,
 		},
 		Cache: cache,
 		Ui:    ui,

packer/core.go

@@ -5,6 +5,7 @@ import (
 	"sort"
 
 	"github.com/hashicorp/go-multierror"
+	"github.com/hashicorp/go-version"
 	"github.com/mitchellh/packer/template"
 	"github.com/mitchellh/packer/template/interpolate"
 )
@@ -17,6 +18,7 @@ type Core struct {
 	components ComponentFinder
 	variables  map[string]string
 	builds     map[string]*template.Builder
+	version    string
 }
 
 // CoreConfig is the structure for initializing a new Core. Once a CoreConfig
@@ -25,6 +27,7 @@ type CoreConfig struct {
 	Components ComponentFinder
 	Template   *template.Template
 	Variables  map[string]string
+	Version    string
 }
 
 // The function type used to lookup Builder implementations.
@@ -55,6 +58,7 @@ func NewCore(c *CoreConfig) (*Core, error) {
 		Template:   c.Template,
 		components: c.Components,
 		variables:  c.Variables,
+		version:    c.Version,
 	}
 	if err := result.validate(); err != nil {
 		return nil, err
@@ -226,6 +230,29 @@ func (c *Core) validate() error {
 		return err
 	}
 
+	// Validate the minimum version is satisfied
+	if c.Template.MinVersion != "" {
+		versionActual, err := version.NewVersion(c.version)
+		if err != nil {
+			// This shouldn't happen since we set it via the compiler
+			panic(err)
+		}
+
+		versionMin, err := version.NewVersion(c.Template.MinVersion)
+		if err != nil {
+			return fmt.Errorf(
+				"min_version is invalid: %s", err)
+		}
+
+		if versionActual.LessThan(versionMin) {
+			return fmt.Errorf(
+				"This template requires a minimum Packer version of %s,\n"+
+					"but version %s is running.",
+				versionMin,
+				versionActual)
+		}
+	}
+
 	// Validate variables are set
 	var err error
 	for n, v := range c.Template.Variables {

packer/core_test.go

@@ -484,6 +484,19 @@ func TestCoreValidate(t *testing.T) {
 			map[string]string{"foo": "bar"},
 			false,
 		},
+
+		// Min version good
+		{
+			"validate-min-version.json",
+			map[string]string{"foo": "bar"},
+			false,
+		},
+
+		{
+			"validate-min-version-high.json",
+			map[string]string{"foo": "bar"},
+			true,
+		},
 	}
 
 	for _, tc := range cases {
@@ -501,6 +514,7 @@ func TestCoreValidate(t *testing.T) {
 		_, err = NewCore(&CoreConfig{
 			Template:  tpl,
 			Variables: tc.Vars,
+			Version:   "1.0.0",
 		})
 		if (err != nil) != tc.Err {
 			t.Fatalf("err: %s\n\n%s", tc.File, err)

packer/test-fixtures/validate-min-version-high.json

@@ -0,0 +1,7 @@
+{
+    "min_packer_version": "2.1.0",
+
+    "builders": [
+        {"type": "foo"}
+    ]
+}

packer/test-fixtures/validate-min-version.json

@@ -0,0 +1,7 @@
+{
+    "min_packer_version": "0.1.0",
+
+    "builders": [
+        {"type": "foo"}
+    ]
+}