Extend Iptables interface with SaveInto

pkg/kubelet/network/hostport/fake_iptables.go

@@ -228,22 +228,27 @@ func saveChain(chain *fakeChain, data *bytes.Buffer) {
 }
 
 func (f *fakeIPTables) Save(tableName utiliptables.Table) ([]byte, error) {
+	data := bytes.NewBuffer(nil)
+	err := f.SaveInto(tableName, data)
+	return data.Bytes(), err
+}
+
+func (f *fakeIPTables) SaveInto(tableName utiliptables.Table, buffer *bytes.Buffer) error {
 	table, err := f.getTable(tableName)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	data := bytes.NewBuffer(nil)
-	data.WriteString(fmt.Sprintf("*%s\n", table.name))
+	buffer.WriteString(fmt.Sprintf("*%s\n", table.name))
 
 	rules := bytes.NewBuffer(nil)
 	for _, chain := range table.chains {
-		data.WriteString(fmt.Sprintf(":%s - [0:0]\n", string(chain.name)))
+		buffer.WriteString(fmt.Sprintf(":%s - [0:0]\n", string(chain.name)))
 		saveChain(chain, rules)
 	}
-	data.Write(rules.Bytes())
-	data.WriteString("COMMIT\n")
-	return data.Bytes(), nil
+	buffer.Write(rules.Bytes())
+	buffer.WriteString("COMMIT\n")
+	return nil
 }
 
 func (f *fakeIPTables) restore(restoreTableName utiliptables.Table, data []byte, flush utiliptables.FlushFlag) error {

pkg/kubelet/prober/prober.go

@@ -237,6 +237,10 @@ func (pb *prober) newExecInContainer(container v1.Container, containerID kubecon
 	}}
 }
 
+func (eic execInContainer) Run() error {
+	return fmt.Errorf("unimplemented")
+}
+
 func (eic execInContainer) CombinedOutput() ([]byte, error) {
 	return eic.run()
 }
@@ -257,6 +261,10 @@ func (eic execInContainer) SetStdout(out io.Writer) {
 	//unimplemented
 }
 
+func (eic execInContainer) SetStderr(out io.Writer) {
+	//unimplemented
+}
+
 func (eic execInContainer) Stop() {
 	//unimplemented
 }

pkg/probe/exec/exec_test.go

@@ -30,6 +30,10 @@ type FakeCmd struct {
 	err    error
 }
 
+func (f *FakeCmd) Run() error {
+	return nil
+}
+
 func (f *FakeCmd) CombinedOutput() ([]byte, error) {
 	return f.out, f.err
 }
@@ -44,6 +48,8 @@ func (f *FakeCmd) SetStdin(in io.Reader) {}
 
 func (f *FakeCmd) SetStdout(out io.Writer) {}
 
+func (f *FakeCmd) SetStderr(out io.Writer) {}
+
 func (f *FakeCmd) Stop() {}
 
 type fakeExitError struct {

pkg/util/exec/exec.go

@@ -41,6 +41,8 @@ type Interface interface {
 // As more functionality is needed, this can grow.  Since Cmd is a struct, we will have
 // to replace fields with get/set method pairs.
 type Cmd interface {
+	// Run runs the command to the completion.
+	Run() error
 	// CombinedOutput runs the command and returns its combined standard output
 	// and standard error.  This follows the pattern of package os/exec.
 	CombinedOutput() ([]byte, error)
@@ -49,6 +51,7 @@ type Cmd interface {
 	SetDir(dir string)
 	SetStdin(in io.Reader)
 	SetStdout(out io.Writer)
+	SetStderr(out io.Writer)
 	// Stops the command by sending SIGTERM. It is not guaranteed the
 	// process will stop before this function returns. If the process is not
 	// responding, an internal timer function will send a SIGKILL to force
@@ -99,6 +102,15 @@ func (cmd *cmdWrapper) SetStdout(out io.Writer) {
 	cmd.Stdout = out
 }
 
+func (cmd *cmdWrapper) SetStderr(out io.Writer) {
+	cmd.Stderr = out
+}
+
+// Run is part of the Cmd interface.
+func (cmd *cmdWrapper) Run() error {
+	return (*osexec.Cmd)(cmd).Run()
+}
+
 // CombinedOutput is part of the Cmd interface.
 func (cmd *cmdWrapper) CombinedOutput() ([]byte, error) {
 	out, err := (*osexec.Cmd)(cmd).CombinedOutput()

pkg/util/exec/fake_exec.go

@@ -52,6 +52,7 @@ type FakeCmd struct {
 	Dirs                 []string
 	Stdin                io.Reader
 	Stdout               io.Writer
+	Stderr               io.Writer
 }
 
 func InitFakeCmd(fake *FakeCmd, cmd string, args ...string) Cmd {
@@ -73,6 +74,14 @@ func (fake *FakeCmd) SetStdout(out io.Writer) {
 	fake.Stdout = out
 }
 
+func (fake *FakeCmd) SetStderr(out io.Writer) {
+	fake.Stderr = out
+}
+
+func (fake *FakeCmd) Run() error {
+	return fmt.Errorf("unimplemented")
+}
+
 func (fake *FakeCmd) CombinedOutput() ([]byte, error) {
 	if fake.CombinedOutputCalls > len(fake.CombinedOutputScript)-1 {
 		panic("ran out of CombinedOutput() actions")

pkg/util/iptables/iptables.go

@@ -56,6 +56,8 @@ type Interface interface {
 	IsIpv6() bool
 	// Save calls `iptables-save` for table.
 	Save(table Table) ([]byte, error)
+	// SaveInto calls `iptables-save` for table and stores result in a given buffer.
+	SaveInto(table Table, buffer *bytes.Buffer) error
 	// Restore runs `iptables-restore` passing data through []byte.
 	// table is the Table to restore
 	// data should be formatted like the output of Save()
@@ -315,6 +317,20 @@ func (runner *runner) Save(table Table) ([]byte, error) {
 	return runner.exec.Command(cmdIPTablesSave, args...).CombinedOutput()
 }
 
+// SaveInto is part of Interface.
+func (runner *runner) SaveInto(table Table, buffer *bytes.Buffer) error {
+	runner.mu.Lock()
+	defer runner.mu.Unlock()
+
+	// run and return
+	args := []string{"-t", string(table)}
+	glog.V(4).Infof("running iptables-save %v", args)
+	cmd := runner.exec.Command(cmdIPTablesSave, args...)
+	cmd.SetStdout(buffer)
+	cmd.SetStderr(buffer)
+	return cmd.Run()
+}
+
 // Restore is part of Interface.
 func (runner *runner) Restore(table Table, data []byte, flush FlushFlag, counters RestoreCountersFlag) error {
 	// setup args

pkg/util/iptables/testing/fake.go

@@ -17,6 +17,7 @@ limitations under the License.
 package testing
 
 import (
+	"bytes"
 	"fmt"
 	"strings"
 
@@ -78,6 +79,11 @@ func (f *FakeIPTables) Save(table iptables.Table) ([]byte, error) {
 	return lines, nil
 }
 
+func (f *FakeIPTables) SaveInto(table iptables.Table, buffer *bytes.Buffer) error {
+	buffer.Write(f.Lines)
+	return nil
+}
+
 func (*FakeIPTables) Restore(table iptables.Table, data []byte, flush iptables.FlushFlag, counters iptables.RestoreCountersFlag) error {
 	return nil
 }