fix: broken tls in jx preview

fixes #2196

- the `omitempty` json tag was missing from the ExposeControllerConfig struct, which resulted in empty values being present in the extraValues.yaml file - thus overriding valid values from the values.yaml file
- the cmdline flags passed through `jx preview` for the ExposeControllerConfig struct were not used to generate the extraValues.yaml file

also extracting the preview values config in a func, to unit test it

pkg/config/helm_values.go

@@ -9,10 +9,10 @@ import (
 
 type ExposeControllerConfig struct {
 	Domain   string `yaml:"domain,omitempty"`
-	Exposer  string `yaml:"exposer"`
-	HTTP     string `yaml:"http"`
-	TLSAcme  string `yaml:"tlsacme"`
-	PathMode string `yaml:"pathMode"`
+	Exposer  string `yaml:"exposer,omitempty"`
+	HTTP     string `yaml:"http,omitempty"`
+	TLSAcme  string `yaml:"tlsacme,omitempty"`
+	PathMode string `yaml:"pathMode,omitempty"`
 }
 type ExposeController struct {
 	Config      ExposeControllerConfig `yaml:"config,omitempty"`

pkg/jx/cmd/preview.go

@@ -425,30 +425,11 @@ func (o *PreviewOptions) Run() error {
 		return err
 	}
 
-	repository, err := getImageName()
-	if err != nil {
-		return err
-	}
-
-	tag, err := getImageTag()
+	values, err := o.GetPreviewValuesConfig(domain)
 	if err != nil {
 		return err
 	}
 
-	values := config.PreviewValuesConfig{
-		ExposeController: &config.ExposeController{
-			Config: config.ExposeControllerConfig{
-				Domain: domain,
-			},
-		},
-		Preview: &config.Preview{
-			Image: &config.Image{
-				Repository: repository,
-				Tag:        tag,
-			},
-		},
-	}
-
 	config, err := values.String()
 	if err != nil {
 		return err
@@ -774,6 +755,35 @@ func (o *PreviewOptions) defaultValues(ns string, warnMissingName bool) error {
 	return nil
 }
 
+// GetPreviewValuesConfig returns the PreviewValuesConfig to use as extraValues for helm
+func (o *PreviewOptions) GetPreviewValuesConfig(domain string) (*config.PreviewValuesConfig, error) {
+	repository, err := getImageName()
+	if err != nil {
+		return nil, err
+	}
+
+	tag, err := getImageTag()
+	if err != nil {
+		return nil, err
+	}
+
+	if o.HelmValuesConfig.ExposeController == nil {
+		o.HelmValuesConfig.ExposeController = &config.ExposeController{}
+	}
+	o.HelmValuesConfig.ExposeController.Config.Domain = domain
+
+	values := config.PreviewValuesConfig{
+		ExposeController: o.HelmValuesConfig.ExposeController,
+		Preview: &config.Preview{
+			Image: &config.Image{
+				Repository: repository,
+				Tag:        tag,
+			},
+		},
+	}
+	return &values, nil
+}
+
 func writePreviewURL(o *PreviewOptions, url string) {
 	previewFileName := filepath.Join(o.Dir, ".previewUrl")
 	err := ioutil.WriteFile(previewFileName, []byte(url), 0644)

pkg/jx/cmd/preview_test.go

@@ -0,0 +1,89 @@
+package cmd_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/jenkins-x/jx/pkg/config"
+	"github.com/jenkins-x/jx/pkg/jx/cmd"
+)
+
+func TestGetPreviewValuesConfig(t *testing.T) {
+	tests := []struct {
+		opts               cmd.PreviewOptions
+		env                map[string]string
+		domain             string
+		expectedYAMLConfig string
+	}{
+		{
+			opts: cmd.PreviewOptions{
+				HelmValuesConfig: config.HelmValuesConfig{
+					ExposeController: &config.ExposeController{},
+				},
+			},
+			env: map[string]string{
+				cmd.DOCKER_REGISTRY: "my.registry",
+				cmd.ORG:             "my-org",
+				cmd.APP_NAME:        "my-app",
+				cmd.PREVIEW_VERSION: "1.0.0",
+			},
+			expectedYAMLConfig: `expose: {}
+preview:
+  image:
+    repository: my.registry/my-org/my-app
+    tag: 1.0.0
+`,
+		},
+		{
+			opts: cmd.PreviewOptions{
+				HelmValuesConfig: config.HelmValuesConfig{
+					ExposeController: &config.ExposeController{
+						Config: config.ExposeControllerConfig{
+							HTTP:    "false",
+							TLSAcme: "true",
+						},
+					},
+				},
+			},
+			env: map[string]string{
+				cmd.DOCKER_REGISTRY: "my.registry",
+				cmd.ORG:             "my-org",
+				cmd.APP_NAME:        "my-app",
+				cmd.PREVIEW_VERSION: "1.0.0",
+			},
+			domain: "jenkinsx.io",
+			expectedYAMLConfig: `expose:
+  config:
+    domain: jenkinsx.io
+    http: "false"
+    tlsacme: "true"
+preview:
+  image:
+    repository: my.registry/my-org/my-app
+    tag: 1.0.0
+`,
+		},
+	}
+
+	for i, test := range tests {
+		for k, v := range test.env {
+			os.Setenv(k, v)
+		}
+
+		config, err := test.opts.GetPreviewValuesConfig(test.domain)
+		if err != nil {
+			t.Errorf("[%d] got unexpected err: %v", i, err)
+			continue
+		}
+
+		configYAML, err := config.String()
+		if err != nil {
+			t.Errorf("[%d] %v", i, err)
+			continue
+		}
+
+		if test.expectedYAMLConfig != configYAML {
+			t.Errorf("[%d] expected %#v but got %#v", i, test.expectedYAMLConfig, configYAML)
+		}
+	}
+}