Allow build args in target image config

Signed-off-by: Peter Engelbert <pmengelbert@gmail.com>
Co-authored-by: Brian Goff <cpuguy83@gmail.com>

load.go

@@ -199,6 +199,10 @@ func (s *Spec) SubstituteArgs(env map[string]string, opts ...SubstituteOpt) erro
 		}
 	}
 
+	if err := s.Image.processBuildArgs(lex, args, cfg.AllowArg); err != nil {
+		appendErr(errors.Wrap(err, "package config"))
+	}
+
 	if err := s.Dependencies.processBuildArgs(args, cfg.AllowArg); err != nil {
 		appendErr(errors.Wrap(err, "dependencies"))
 	}
@@ -473,7 +477,7 @@ func validateSymlinks(symlinks map[string]SymlinkTarget) error {
 			errs = append(errs, err)
 		}
 
-		if (cfg.Path != "" && len(cfg.Paths) > 0) || (cfg.Path == "" && len(cfg.Paths) == 0 ) {
+		if (cfg.Path != "" && len(cfg.Paths) > 0) || (cfg.Path == "" && len(cfg.Paths) == 0) {
 			err = fmt.Errorf("'path' and 'paths' fields are mutually exclusive, and at least one is required: "+
 				"symlink to %s", oldpath)
 
@@ -536,3 +540,22 @@ func validateSymlinks(symlinks map[string]SymlinkTarget) error {
 
 	return goerrors.Join(errs...)
 }
+
+func (img *ImageConfig) processBuildArgs(lex *shell.Lex, args map[string]string, allowArg func(string) bool) error {
+	if img == nil {
+		return nil
+	}
+
+	var errs error
+
+	for k, v := range img.Labels {
+		updated, err := expandArgs(lex, v, args, allowArg)
+		if err != nil {
+			errs = goerrors.Join(errs, errors.Wrapf(err, "env %s=%s", k, v))
+			continue
+		}
+		img.Labels[k] = updated
+	}
+
+	return errs
+}

load_test.go

@@ -590,6 +590,14 @@ func TestSpec_SubstituteBuildArgs(t *testing.T) {
 					Args: maps.Clone(pairs),
 				},
 			},
+			Image: &ImageConfig{
+				Labels: map[string]string{
+					"foo": "$FOO",
+				},
+				Volumes: map[string]struct{}{
+					"": {},
+				},
+			},
 		},
 	}
 
@@ -611,7 +619,7 @@ func TestSpec_SubstituteBuildArgs(t *testing.T) {
 	assert.Check(t, cmp.Equal(spec.Targets["t2"].PackageConfig.Signer.Args["BAR"], bar))
 	assert.Check(t, cmp.Equal(spec.Targets["t2"].PackageConfig.Signer.Args["WHATEVER"], argWithDefault))
 	assert.Check(t, cmp.Equal(spec.Targets["t2"].PackageConfig.Signer.Args["REGULAR"], plainOleValue))
-
+	assert.Check(t, cmp.Equal(spec.Targets["t2"].Image.Labels["foo"], foo))
 }
 
 func TestCustomRepoFillDefaults(t *testing.T) {

target.go

@@ -70,6 +70,10 @@ func (t *Target) processBuildArgs(lex *shell.Lex, args map[string]string, allowA
 		}
 	}
 
+	if err := t.Image.processBuildArgs(lex, args, allowArg); err != nil {
+		errs = append(errs, errors.Wrap(err, "package config"))
+	}
+
 	if err := t.Dependencies.processBuildArgs(args, allowArg); err != nil {
 		errs = append(errs, errors.Wrap(err, "dependencies"))
 	}