give correct error when variable is unset

hcl2template/parser.go

@@ -101,6 +101,11 @@ func (p *Parser) parse(filename string, vars map[string]string) (*PackerConfig,
 		}
 	}
 
+	_, moreDiags := cfg.InputVariables.Values()
+	diags = append(diags, moreDiags...)
+	_, moreDiags = cfg.LocalVariables.Values()
+	diags = append(diags, moreDiags...)
+
 	// parse var files
 	{
 		hclVarFiles, jsonVarFiles, moreDiags := GetHCL2Files(filename, hcl2VarFileExt, hcl2VarJsonFileExt)

hcl2template/types.build.go

@@ -60,6 +60,9 @@ func (p *Parser) decodeBuildConfig(block *hcl.Block) (*BuildBlock, hcl.Diagnosti
 		Config      hcl.Body `hcl:",remain"`
 	}
 	diags := gohcl.DecodeBody(block.Body, nil, &b)
+	if diags.HasErrors() {
+		return nil, diags
+	}
 
 	for _, buildFrom := range b.FromSources {
 		ref := sourceRefFromString(buildFrom)
@@ -84,6 +87,9 @@ func (p *Parser) decodeBuildConfig(block *hcl.Block) (*BuildBlock, hcl.Diagnosti
 
 	content, moreDiags := b.Config.Content(buildSchema)
 	diags = append(diags, moreDiags...)
+	if diags.HasErrors() {
+		return nil, diags
+	}
 	for _, block := range content.Blocks {
 		switch block.Type {
 		case buildProvisionerLabel:

hcl2template/types.packer_config.go

@@ -30,11 +30,13 @@ type PackerConfig struct {
 // decoder in order to tell what is the actual value of a var or a local and
 // the list of defined functions.
 func (cfg *PackerConfig) EvalContext() *hcl.EvalContext {
+	v, _ := cfg.InputVariables.Values()
+	l, _ := cfg.LocalVariables.Values()
 	ectx := &hcl.EvalContext{
 		Functions: Functions(cfg.Basedir),
 		Variables: map[string]cty.Value{
-			"var":   cty.ObjectVal(cfg.InputVariables.Values()),
-			"local": cty.ObjectVal(cfg.LocalVariables.Values()),
+			"var":   cty.ObjectVal(v),
+			"local": cty.ObjectVal(l),
 		},
 	}
 	return ectx

hcl2template/types.variables.go

@@ -56,10 +56,11 @@ func (v *Variable) Value() (cty.Value, *hcl.Diagnostic) {
 			return value, nil
 		}
 	}
-	return cty.NilVal, &hcl.Diagnostic{
+
+	return cty.UnknownVal(v.Type), &hcl.Diagnostic{
 		Severity: hcl.DiagError,
 		Summary:  "Unset variable",
-		Detail: "A used variable must be set; see " +
+		Detail: "A used variable must be set or have a default value; see " +
 			"https://packer.io/docs/configuration/from-1.5/syntax.html for details.",
 		Context: v.block.DefRange.Ptr(),
 	}
@@ -67,12 +68,15 @@ func (v *Variable) Value() (cty.Value, *hcl.Diagnostic) {
 
 type Variables map[string]*Variable
 
-func (variables Variables) Values() map[string]cty.Value {
+func (variables Variables) Values() (map[string]cty.Value, hcl.Diagnostics) {
 	res := map[string]cty.Value{}
+	var diags hcl.Diagnostics
 	for k, v := range variables {
-		res[k], _ = v.Value()
+		var diag *hcl.Diagnostic
+		res[k], diag = v.Value()
+		diags = append(diags, diag)
 	}
-	return res
+	return res, diags
 }
 
 // decodeConfig decodes a "variables" section the way packer 1 used to

hcl2template/types.variables_test.go

@@ -10,7 +10,6 @@ import (
 	"github.com/zclconf/go-cty/cty/convert"
 
 	"github.com/hashicorp/hcl/v2"
-	"github.com/hashicorp/packer/builder/null"
 	"github.com/hashicorp/packer/packer"
 )
 
@@ -119,12 +118,8 @@ func TestParse_variables(t *testing.T) {
 				},
 			},
 			false, false,
-			[]packer.Build{
-				&packer.CoreBuild{
-					Builder: &null.Builder{},
-				},
-			},
-			false,
+			[]packer.Build{},
+			true,
 		},
 	}
 	testParse(t, tests)