add HostAlias support for HostNetwork pods

pkg/kubelet/kubelet_pods.go

@@ -233,7 +233,7 @@ func ensureHostsFile(fileName, hostIP, hostName, hostDomainName string, hostAlia
 		// if Pod is using host network, read hosts file from the node's filesystem.
 		// `etcHostsPath` references the location of the hosts file on the node.
 		// `/etc/hosts` for *nix systems.
-		hostsFileContent, err = nodeHostsFileContent(etcHostsPath)
+		hostsFileContent, err = nodeHostsFileContent(etcHostsPath, hostAliases)
 		if err != nil {
 			return err
 		}
@@ -246,8 +246,13 @@ func ensureHostsFile(fileName, hostIP, hostName, hostDomainName string, hostAlia
 }
 
 // nodeHostsFileContent reads the content of node's hosts file.
-func nodeHostsFileContent(hostsFilePath string) ([]byte, error) {
-	return ioutil.ReadFile(hostsFilePath)
+func nodeHostsFileContent(hostsFilePath string, hostAliases []v1.HostAlias) ([]byte, error) {
+	hostsFileContent, err := ioutil.ReadFile(hostsFilePath)
+	if err != nil {
+		return nil, err
+	}
+	hostsFileContent = append(hostsFileContent, hostsEntriesFromHostAliases(hostAliases)...)
+	return hostsFileContent, nil
 }
 
 // managedHostsFileContent generates the content of the managed etc hosts based on Pod IP and other

pkg/kubelet/kubelet_pods_test.go

@@ -184,11 +184,23 @@ func TestMakeMounts(t *testing.T) {
 
 func TestNodeHostsFileContent(t *testing.T) {
 	testCases := []struct {
-		hostsFileName   string
-		expectedContent string
+		hostsFileName            string
+		hostAliases              []v1.HostAlias
+		rawHostsFileContent      string
+		expectedHostsFileContent string
 	}{
 		{
 			"hosts_test_file1",
+			[]v1.HostAlias{},
+			`# hosts file for testing.
+127.0.0.1	localhost
+::1	localhost ip6-localhost ip6-loopback
+fe00::0	ip6-localnet
+fe00::0	ip6-mcastprefix
+fe00::1	ip6-allnodes
+fe00::2	ip6-allrouters
+123.45.67.89	some.domain
+`,
 			`# hosts file for testing.
 127.0.0.1	localhost
 ::1	localhost ip6-localhost ip6-loopback
@@ -201,6 +213,70 @@ fe00::2	ip6-allrouters
 		},
 		{
 			"hosts_test_file2",
+			[]v1.HostAlias{},
+			`# another hosts file for testing.
+127.0.0.1	localhost
+::1	localhost ip6-localhost ip6-loopback
+fe00::0	ip6-localnet
+fe00::0	ip6-mcastprefix
+fe00::1	ip6-allnodes
+fe00::2	ip6-allrouters
+12.34.56.78	another.domain
+`,
+			`# another hosts file for testing.
+127.0.0.1	localhost
+::1	localhost ip6-localhost ip6-loopback
+fe00::0	ip6-localnet
+fe00::0	ip6-mcastprefix
+fe00::1	ip6-allnodes
+fe00::2	ip6-allrouters
+12.34.56.78	another.domain
+`,
+		},
+		{
+			"hosts_test_file1_with_host_aliases",
+			[]v1.HostAlias{
+				{IP: "123.45.67.89", Hostnames: []string{"foo", "bar", "baz"}},
+			},
+			`# hosts file for testing.
+127.0.0.1	localhost
+::1	localhost ip6-localhost ip6-loopback
+fe00::0	ip6-localnet
+fe00::0	ip6-mcastprefix
+fe00::1	ip6-allnodes
+fe00::2	ip6-allrouters
+123.45.67.89	some.domain
+`,
+			`# hosts file for testing.
+127.0.0.1	localhost
+::1	localhost ip6-localhost ip6-loopback
+fe00::0	ip6-localnet
+fe00::0	ip6-mcastprefix
+fe00::1	ip6-allnodes
+fe00::2	ip6-allrouters
+123.45.67.89	some.domain
+
+# Entries added by HostAliases.
+123.45.67.89	foo
+123.45.67.89	bar
+123.45.67.89	baz
+`,
+		},
+		{
+			"hosts_test_file2_with_host_aliases",
+			[]v1.HostAlias{
+				{IP: "123.45.67.89", Hostnames: []string{"foo", "bar", "baz"}},
+				{IP: "456.78.90.123", Hostnames: []string{"park", "doo", "boo"}},
+			},
+			`# another hosts file for testing.
+127.0.0.1	localhost
+::1	localhost ip6-localhost ip6-loopback
+fe00::0	ip6-localnet
+fe00::0	ip6-mcastprefix
+fe00::1	ip6-allnodes
+fe00::2	ip6-allrouters
+12.34.56.78	another.domain
+`,
 			`# another hosts file for testing.
 127.0.0.1	localhost
 ::1	localhost ip6-localhost ip6-loopback
@@ -209,18 +285,26 @@ fe00::0	ip6-mcastprefix
 fe00::1	ip6-allnodes
 fe00::2	ip6-allrouters
 12.34.56.78	another.domain
+
+# Entries added by HostAliases.
+123.45.67.89	foo
+123.45.67.89	bar
+123.45.67.89	baz
+456.78.90.123	park
+456.78.90.123	doo
+456.78.90.123	boo
 `,
 		},
 	}
 
 	for _, testCase := range testCases {
-		tmpdir, err := writeHostsFile(testCase.hostsFileName, testCase.expectedContent)
+		tmpdir, err := writeHostsFile(testCase.hostsFileName, testCase.rawHostsFileContent)
 		require.NoError(t, err, "could not create a temp hosts file")
 		defer os.RemoveAll(tmpdir)
 
-		actualContent, fileReadErr := nodeHostsFileContent(filepath.Join(tmpdir, testCase.hostsFileName))
+		actualContent, fileReadErr := nodeHostsFileContent(filepath.Join(tmpdir, testCase.hostsFileName), testCase.hostAliases)
 		require.NoError(t, fileReadErr, "could not create read hosts file")
-		assert.Equal(t, testCase.expectedContent, string(actualContent), "hosts file content not expected")
+		assert.Equal(t, testCase.expectedHostsFileContent, string(actualContent), "hosts file content not expected")
 	}
 }