replacing hard coded cluster.local with variable

pkg/reconciler/names.go

@@ -16,10 +16,17 @@ limitations under the License.
 
 package reconciler
 
-import "fmt"
+import (
+	"fmt"
+	"github.com/knative/serving/pkg/utils"
+)
 
 func GetK8sServiceFullname(name string, namespace string) string {
-	return fmt.Sprintf("%s.%s.svc.cluster.local", name, namespace)
+	clusterDomainName, err := utils.GetClusterDomainName()
+	if err != nil {
+		clusterDomainName = "cluster.local"
+	}
+	return fmt.Sprintf("%s.%s.svc.%s", name, namespace, clusterDomainName)
 }
 
 func GetServingK8SServiceNameForObj(name string) string {

pkg/utils/utils.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2018 The Knative Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package utils
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+const (
+	resolverFileName = "/etc/resolv.conf"
+)
+
+// GetClusterDomainName returns cluster's domain name or an error
+// Closes issue: https://github.com/knative/eventing/issues/714
+func GetClusterDomainName() (string, error) {
+	f, err := os.Open(resolverFileName)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	return getClusterDomainName(f)
+}
+
+func getClusterDomainName(r io.Reader) (string, error) {
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		elements := strings.Split(scanner.Text(), " ")
+		if elements[0] != "search" {
+			continue
+		}
+		for i := 1; i < len(elements)-1; i++ {
+			if strings.HasPrefix(elements[i], "svc.") {
+				return elements[i][4:], nil
+			}
+		}
+	}
+	return "", fmt.Errorf("%s does not seem to be a valid kubernetes resolv.conf file", resolverFileName)
+}

pkg/utils/utils_test.go

@@ -0,0 +1,80 @@
+/*
+Copyright 2018 The Knative Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package utils
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestGetDomainName(t *testing.T) {
+	tests := []struct {
+		descr      string
+		resolvConf string
+		domainName string
+		shouldFail bool
+	}{
+		{
+			descr: "all good",
+			resolvConf: `
+nameserver 1.1.1.1
+search default.svc.abc.com svc.abc.com abc.com
+options ndots:5
+`,
+			domainName: "abc.com",
+			shouldFail: false,
+		},
+		{
+			descr: "missing search line",
+			resolvConf: `
+nameserver 1.1.1.1
+options ndots:5
+`,
+			domainName: "",
+			shouldFail: true,
+		},
+		{
+			descr: "non k8s resolv.conf format",
+			resolvConf: `
+nameserver 1.1.1.1
+search  abc.com xyz.com
+options ndots:5
+`,
+			domainName: "",
+			shouldFail: true,
+		},
+	}
+	for _, tt := range tests {
+		dn, err := getClusterDomainName(strings.NewReader(tt.resolvConf))
+		if err != nil {
+			if !tt.shouldFail {
+				t.Errorf("Test %s failed with error: %q but is not supposed to.", tt.descr, err)
+			} else {
+				continue
+			}
+		}
+		if err == nil {
+			if tt.shouldFail {
+				t.Errorf("Test %s succeeded but supposed to fail.", tt.descr)
+				continue
+			}
+			if dn != tt.domainName {
+				t.Errorf("Test %s failed expected %s but got %s", tt.descr, tt.domainName, dn)
+			}
+		}
+	}
+}