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Merge pull request #50 from Crazykev/resolv

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Generate and maintain resolv.conf for sandbox
This commit is contained in:
Lantao Liu 2017-06-09 09:41:23 -07:00 committed by GitHub
commit 227dbe97f2
7 changed files with 160 additions and 20 deletions
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7
pkg/os/os.go
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@ -18,6 +18,7 @@ package os
import (
"io"
"io/ioutil"
"os"
"golang.org/x/net/context"
@ -33,6 +34,7 @@ type OS interface {
OpenFifo(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error)
Stat(name string) (os.FileInfo, error)
CopyFile(src, dest string, perm os.FileMode) error
WriteFile(filename string, data []byte, perm os.FileMode) error
}
// RealOS is used to dispatch the real system level operations.
@ -75,3 +77,8 @@ func (RealOS) CopyFile(src, dest string, perm os.FileMode) error {
_, err = io.Copy(out, in)
return err
}
// WriteFile will call ioutil.WriteFile to write data into a file.
func (RealOS) WriteFile(filename string, data []byte, perm os.FileMode) error {
return ioutil.WriteFile(filename, data, perm)
}

13
pkg/os/testing/fake_os.go
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@ -36,6 +36,7 @@ type FakeOS struct {
OpenFifoFn func(context.Context, string, int, os.FileMode) (io.ReadWriteCloser, error)
StatFn func(string) (os.FileInfo, error)
CopyFileFn func(string, string, os.FileMode) error
WriteFileFn func(string, []byte, os.FileMode) error
errors map[string]error
}
@ -142,3 +143,15 @@ func (f *FakeOS) CopyFile(src, dest string, perm os.FileMode) error {
}
return nil
}
// WriteFile is a fake call that invokes WriteFileFn or just return nil.
func (f *FakeOS) WriteFile(filename string, data []byte, perm os.FileMode) error {
if err := f.getError("WriteFile"); err != nil {
return err
}
if f.WriteFileFn != nil {
return f.WriteFileFn(filename, data, perm)
}
return nil
}

16
pkg/server/container_start.go
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@ -292,10 +292,6 @@ func (c *criContainerdService) generateContainerSpec(id string, sandboxPid uint3
// TODO(random-liu): [P2] Add apparmor and seccomp.
// TODO(random-liu): [P1] Bind mount sandbox /dev/shm.
// TODO(random-liu): [P0] Bind mount sandbox resolv.conf.
return g.Spec(), nil
}
@ -307,9 +303,17 @@ func (c *criContainerdService) generateContainerMounts(sandboxRootDir string, co
mounts = append(mounts, &runtime.Mount{
ContainerPath: etcHosts,
HostPath: getSandboxHosts(sandboxRootDir),
Readonly: securityContext.ReadonlyRootfs,
Readonly: securityContext.GetReadonlyRootfs(),
})
// TODO(random-liu): [P0] Mount sandbox resolv.config.
// Mount sandbox resolv.config.
// TODO: Need to figure out whether we should always mount it as read-only
mounts = append(mounts, &runtime.Mount{
ContainerPath: resolvConfPath,
HostPath: getResolvPath(sandboxRootDir),
Readonly: securityContext.GetReadonlyRootfs(),
})
// TODO(random-liu): [P0] Mount sandbox /dev/shm.
return mounts
}

26
pkg/server/container_start_test.go
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@ -309,23 +309,37 @@ func TestGenerateContainerMounts(t *testing.T) {
securityContext *runtime.LinuxContainerSecurityContext
expectedMounts []*runtime.Mount
}{
"should setup ro /etc/hosts mount when rootfs is read-only": {
"should setup ro mount when rootfs is read-only": {
securityContext: &runtime.LinuxContainerSecurityContext{
ReadonlyRootfs: true,
},
expectedMounts: []*runtime.Mount{{
expectedMounts: []*runtime.Mount{
{
ContainerPath: "/etc/hosts",
HostPath: testSandboxRootDir + "/hosts",
Readonly: true,
}},
},
"should setup rw /etc/hosts mount when rootfs is read-write": {
{
ContainerPath: resolvConfPath,
HostPath: testSandboxRootDir + "/resolv.conf",
Readonly: true,
},
},
},
"should setup rw mount when rootfs is read-write": {
securityContext: &runtime.LinuxContainerSecurityContext{},
expectedMounts: []*runtime.Mount{{
expectedMounts: []*runtime.Mount{
{
ContainerPath: "/etc/hosts",
HostPath: testSandboxRootDir + "/hosts",
Readonly: false,
}},
},
{
ContainerPath: resolvConfPath,
HostPath: getResolvPath(testSandboxRootDir),
Readonly: false,
},
},
},
} {
config := &runtime.ContainerConfig{

10
pkg/server/helpers.go
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@ -69,6 +69,9 @@ const (
sandboxesDir = "sandboxes"
// containersDir contains all container root.
containersDir = "containers"
// According to http://man7.org/linux/man-pages/man5/resolv.conf.5.html:
// "The search list is currently limited to six domains with a total of 256 characters."
maxDNSSearches = 6
// stdinNamedPipe is the name of stdin named pipe.
stdinNamedPipe = "stdin"
// stdoutNamedPipe is the name of stdout named pipe.
@ -87,6 +90,8 @@ const (
pidNSFormat = "/proc/%v/ns/pid"
// etcHosts is the default path of /etc/hosts file.
etcHosts = "/etc/hosts"
// resolvConfPath is the abs path of resolv.conf on host or container.
resolvConfPath = "/etc/resolv.conf"
)
// generateID generates a random unique id.
@ -149,6 +154,11 @@ func getSandboxHosts(sandboxRootDir string) string {
return filepath.Join(sandboxRootDir, "hosts")
}
// getResolvPath returns resolv.conf filepath for specified sandbox.
func getResolvPath(sandboxRoot string) string {
return filepath.Join(sandboxRoot, "resolv.conf")
}
// prepareStreamingPipes prepares stream named pipe for container. returns nil
// streaming handler if corresponding stream path is empty.
func (c *criContainerdService) prepareStreamingPipes(ctx context.Context, stdin, stdout, stderr string) (

50
pkg/server/sandbox_run.go
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@ -19,6 +19,7 @@ package server
import (
"encoding/json"
"fmt"
"strings"
"time"
"github.com/containerd/containerd/api/services/execution"
@ -303,8 +304,55 @@ func (c *criContainerdService) setupSandboxFiles(rootDir string, config *runtime
if err := c.os.CopyFile(etcHosts, sandboxEtcHosts, 0666); err != nil {
return fmt.Errorf("failed to generate sandbox hosts file %q: %v", sandboxEtcHosts, err)
}
// TODO(random-liu): [P0] Set DNS options. Maintain a resolv.conf for the sandbox.
// Set DNS options. Maintain a resolv.conf for the sandbox.
var err error
resolvContent := ""
if dnsConfig := config.GetDnsConfig(); dnsConfig != nil {
resolvContent, err = parseDNSOptions(dnsConfig.Servers, dnsConfig.Searches, dnsConfig.Options)
if err != nil {
return fmt.Errorf("failed to parse sandbox DNSConfig %+v: %v", dnsConfig, err)
}
}
resolvPath := getResolvPath(rootDir)
if resolvContent == "" {
// copy host's resolv.conf to resolvPath
err = c.os.CopyFile(resolvConfPath, resolvPath, 0644)
if err != nil {
return fmt.Errorf("failed to copy host's resolv.conf to %q: %v", resolvPath, err)
}
} else {
err = c.os.WriteFile(resolvPath, []byte(resolvContent), 0644)
if err != nil {
return fmt.Errorf("failed to write resolv content to %q: %v", resolvPath, err)
}
}
// TODO(random-liu): [P0] Deal with /dev/shm. Use host for HostIpc, and create and mount for
// non-HostIpc. What about mqueue?
return nil
}
// parseDNSOptions parse DNS options into resolv.conf format content,
// if none option is specified, will return empty with no error.
func parseDNSOptions(servers, searches, options []string) (string, error) {
resolvContent := ""
if len(searches) > maxDNSSearches {
return "", fmt.Errorf("DNSOption.Searches has more than 6 domains")
}
if len(searches) > 0 {
resolvContent += fmt.Sprintf("search %s\n", strings.Join(searches, " "))
}
if len(servers) > 0 {
resolvContent += fmt.Sprintf("nameserver %s\n", strings.Join(servers, "\nnameserver "))
}
if len(options) > 0 {
resolvContent += fmt.Sprintf("options %s\n", strings.Join(options, " "))
}
return resolvContent, nil
}

46
pkg/server/sandbox_run_test.go
View File

@ -161,6 +161,7 @@ func TestSetupSandboxFiles(t *testing.T) {
testRootDir := "test-sandbox-root"
expectedCopys := [][]interface{}{
{"/etc/hosts", testRootDir + "/hosts", os.FileMode(0666)},
{"/etc/resolv.conf", testRootDir + "/resolv.conf", os.FileMode(0644)},
}
c := newTestCRIContainerdService()
var copys [][]interface{}
@ -169,7 +170,7 @@ func TestSetupSandboxFiles(t *testing.T) {
return nil
}
c.setupSandboxFiles(testRootDir, nil)
assert.Equal(t, expectedCopys, copys, "should copy /etc/hosts for sandbox")
assert.Equal(t, expectedCopys, copys, "should copy expected files for sandbox")
}
func TestRunPodSandbox(t *testing.T) {
@ -269,5 +270,48 @@ func TestRunPodSandbox(t *testing.T) {
assert.Equal(t, expectedPluginArgument, pluginArgument, "SetUpPod should be called with correct arguments")
}
func TestParseDNSOption(t *testing.T) {
for desc, test := range map[string]struct {
servers []string
searches []string
options []string
expectedContent string
expectErr bool
}{
"empty dns options should return empty content": {},
"non-empty dns options should return correct content": {
servers: []string{"8.8.8.8", "server.google.com"},
searches: []string{"114.114.114.114"},
options: []string{"timeout:1"},
expectedContent: `search 114.114.114.114
nameserver 8.8.8.8
nameserver server.google.com
options timeout:1
`,
},
"should return error if dns search exceeds limit(6)": {
searches: []string{
"server0.google.com",
"server1.google.com",
"server2.google.com",
"server3.google.com",
"server4.google.com",
"server5.google.com",
"server6.google.com",
},
expectErr: true,
},
} {
t.Logf("TestCase %q", desc)
resolvContent, err := parseDNSOptions(test.servers, test.searches, test.options)
if test.expectErr {
assert.Error(t, err)
continue
}
assert.NoError(t, err)
assert.Equal(t, resolvContent, test.expectedContent)
}
}
// TODO(random-liu): [P1] Add unit test for different error cases to make sure
// the function cleans up on error properly.