check for nil

backend/gateway/config.go

@@ -117,7 +117,7 @@ func parseFile(path string, pb proto.Message, template bool) error {
 
 		Solution is to use Clutch-specific templating tokens in the config that are then replaced
 		with the Go Template synax
-		1) $$ in lieu $
+		1) $$ in lieu of $
 		2) [[ ]] in lieu of {{ }}
 	*/
 

backend/service/auditsink/slack/slack.go

@@ -50,6 +50,7 @@ type auditTemplateData struct {
 	Response map[string]interface{}
 }
 
+// TODO: (sperry) expand on helper funcs
 // helper functions to format values in the Go template
 var funcMap = template.FuncMap{
 	// for inputs that are type slice/map, returns a formatted slack list OR `N/A` if the slice/map is empty
@@ -141,7 +142,11 @@ func FormatCustomText(message string, event *auditv1.RequestEvent) (string, erro
 		return "", err
 	}
 
-	return buf.String(), nil
+	// When a value is nil, the Go Template returns "<no value>" in its place. Replacing this with null instead.
+	// We hit this scenario with https://github.com/lyft/clutch/blob/main/api/k8s/v1/k8s.proto#L860
+	sanitized := strings.ReplaceAll(buf.String(), "<no value>", "null")
+
+	return sanitized, nil
 }
 
 // returns the API request/response details saved in an audit event
@@ -176,6 +181,9 @@ func getAuditTemplateData(event *auditv1.RequestEvent) (*auditTemplateData, erro
 
 // for inputs that are type slice/map, returns a formatted slack list OR "None" if the slice/map is empty
 func slackList(data interface{}) string {
+	if data == nil {
+		return "None"
+	}
 	var b strings.Builder
 	const sliceItemFormat = "\n- %v"
 	const mapItemFormat = "\n- %v: %v"

backend/service/auditsink/slack/slack_test.go

@@ -61,11 +61,12 @@ func TestFormatCustomText(t *testing.T) {
 	anyEc2Resp, _ := anypb.New(&ec2v1.ResizeAutoscalingGroupResponse{})
 
 	anyK8sDescribeReq, _ := anypb.New(&k8sapiv1.DescribePodRequest{Name: "foo"})
-	anyK8sDescribeResp, _ := anypb.New(&k8sapiv1.DescribePodResponse{Pod: &k8sapiv1.Pod{PodIp: "000"}})
+	anyK8sDescribeResp, _ := anypb.New(&k8sapiv1.DescribePodResponse{Pod: &k8sapiv1.Pod{PodIp: "000", Labels: map[string]string{}}})
 
 	k8sUpdateReq := &k8sapiv1.UpdatePodRequest{
 		ExpectedObjectMetaFields: &k8sapiv1.ExpectedObjectMetaFields{
 			Annotations: map[string]*k8sapiv1.NullableString{
+				"baz": &k8sapiv1.NullableString{Kind: &k8sapiv1.NullableString_Null{}},
 				"foo": &k8sapiv1.NullableString{Kind: &k8sapiv1.NullableString_Value{Value: "new-value"}},
 			},
 		},
@@ -100,6 +101,15 @@ func TestFormatCustomText(t *testing.T) {
 			},
 			expectedOutput: "foo ip address is 000",
 		},
+		// metdata (labels) value is nil
+		{
+			text: "{{.Request.name}} labels: {{slackList .Response.pod.labels}}",
+			event: &auditv1.RequestEvent{
+				RequestMetadata:  &auditv1.RequestMetadata{Body: anyK8sDescribeReq},
+				ResponseMetadata: &auditv1.ResponseMetadata{Body: anyK8sDescribeResp},
+			},
+			expectedOutput: "foo labels: None",
+		},
 		// metadata that is a map, uses helper slackList
 		{
 			text: "*Updated labels*:{{slackList .Request.objectMetaFields.labels}}",
@@ -126,7 +136,7 @@ func TestFormatCustomText(t *testing.T) {
 				RequestMetadata:  &auditv1.RequestMetadata{Body: anyK8sUpdateReq},
 				ResponseMetadata: &auditv1.ResponseMetadata{Body: anyK8UpdateResp},
 			},
-			expectedOutput: "*Expected Preconditions*:\n- foo: new-value",
+			expectedOutput: "*Expected Preconditions*:\n- baz: null\n- foo: new-value",
 		},
 		// invalid field name
 		{
@@ -184,6 +194,10 @@ func TestSlackList(t *testing.T) {
 			input:          []string{},
 			expectedOutput: "None",
 		},
+		{
+			input:          nil,
+			expectedOutput: "None",
+		},
 	}
 
 	for _, test := range testCases {