builder/docker: config validation test

builder/docker/builder.go

@@ -25,9 +25,15 @@ func (b *Builder) Prepare(raws ...interface{}) ([]string, error) {
 		return nil, err
 	}
 
+	// Accumulate any errors
 	errs := common.CheckUnusedConfig(md)
 	warnings := make([]string, 0)
 
+	// Validate the configuration
+	cwarns, cerrs := b.config.Prepare()
+	errs = packer.MultiErrorAppend(errs, cerrs...)
+	warnings = append(warnings, cwarns...)
+
 	if errs != nil && len(errs.Errors) > 0 {
 		return warnings, errs
 	}

builder/docker/config.go

@@ -1,6 +1,7 @@
 package docker
 
 import (
+	"fmt"
 	"github.com/mitchellh/packer/common"
 	"github.com/mitchellh/packer/packer"
 )
@@ -13,3 +14,31 @@ type Config struct {
 
 	tpl *packer.ConfigTemplate
 }
+
+func (c *Config) Prepare() ([]string, []error) {
+	errs := make([]error, 0)
+
+	templates := map[string]*string{
+		"export_path": &c.ExportPath,
+		"image":       &c.Image,
+	}
+
+	for n, ptr := range templates {
+		var err error
+		*ptr, err = c.tpl.Process(*ptr, nil)
+		if err != nil {
+			errs = append(
+				errs, fmt.Errorf("Error processing %s: %s", n, err))
+		}
+	}
+
+	if c.ExportPath == "" {
+		errs = append(errs, fmt.Errorf("export_path must be specified"))
+	}
+
+	if c.Image == "" {
+		errs = append(errs, fmt.Errorf("image must be specified"))
+	}
+
+	return nil, errs
+}

builder/docker/config_test.go

@@ -0,0 +1,67 @@
+package docker
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func testConfigStruct(t *testing.T) *Config {
+	tpl, err := packer.NewConfigTemplate()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	return &Config{
+		ExportPath: "foo",
+		Image:      "bar",
+		tpl:        tpl,
+	}
+}
+
+func TestConfigPrepare_exportPath(t *testing.T) {
+	c := testConfigStruct(t)
+
+	// No export path
+	c.ExportPath = ""
+	warns, errs := c.Prepare()
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", warns)
+	}
+	if len(errs) <= 0 {
+		t.Fatalf("bad: %#v", errs)
+	}
+
+	// Good export path
+	c.ExportPath = "path"
+	warns, errs = c.Prepare()
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", warns)
+	}
+	if len(errs) > 0 {
+		t.Fatalf("bad: %#v", errs)
+	}
+}
+
+func TestConfigPrepare_image(t *testing.T) {
+	c := testConfigStruct(t)
+
+	// No image
+	c.Image = ""
+	warns, errs := c.Prepare()
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", warns)
+	}
+	if len(errs) <= 0 {
+		t.Fatalf("bad: %#v", errs)
+	}
+
+	// Good image
+	c.Image = "path"
+	warns, errs = c.Prepare()
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", warns)
+	}
+	if len(errs) > 0 {
+		t.Fatalf("bad: %#v", errs)
+	}
+}