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Fix resolv.conf and hosts handling in sandbox

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Two issues:
- container resolv.conf getting regenerated even when no dns configs are passed
- updateHosts should be skipped for host networking mode
- incorrect check on dnsOptions

Signed-off-by: Alessandro Boch <aboch@docker.com>
This commit is contained in:
Alessandro Boch 2015-08-31 15:17:24 -07:00
parent 1e0b620ea7
commit ef659c9049
3 changed files with 119 additions and 75 deletions
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66
libnetwork/resolvconf/resolvconf.go
View file

@ -39,46 +39,69 @@ var lastModified struct {
contents []byte
}
// Get returns the contents of /etc/resolv.conf
func Get() ([]byte, error) {
// File contains the resolv.conf content and its hash
type File struct {
Content []byte
Hash string
}
// Get returns the contents of /etc/resolv.conf and its hash
func Get() (*File, error) {
resolv, err := ioutil.ReadFile("/etc/resolv.conf")
if err != nil {
return nil, err
}
return resolv, nil
hash, err := ioutils.HashData(bytes.NewReader(resolv))
if err != nil {
return nil, err
}
return &File{Content: resolv, Hash: hash}, nil
}
// GetSpecific returns the contents of the user specified resolv.conf file and its hash
func GetSpecific(path string) (*File, error) {
resolv, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
hash, err := ioutils.HashData(bytes.NewReader(resolv))
if err != nil {
return nil, err
}
return &File{Content: resolv, Hash: hash}, nil
}
// GetIfChanged retrieves the host /etc/resolv.conf file, checks against the last hash
// and, if modified since last check, returns the bytes and new hash.
// This feature is used by the resolv.conf updater for containers
func GetIfChanged() ([]byte, string, error) {
func GetIfChanged() (*File, error) {
lastModified.Lock()
defer lastModified.Unlock()
resolv, err := ioutil.ReadFile("/etc/resolv.conf")
if err != nil {
return nil, "", err
return nil, err
}
newHash, err := ioutils.HashData(bytes.NewReader(resolv))
if err != nil {
return nil, "", err
return nil, err
}
if lastModified.sha256 != newHash {
lastModified.sha256 = newHash
lastModified.contents = resolv
return resolv, newHash, nil
return &File{Content: resolv, Hash: newHash}, nil
}
// nothing changed, so return no data
return nil, "", nil
return nil, nil
}
// GetLastModified retrieves the last used contents and hash of the host resolv.conf.
// Used by containers updating on restart
func GetLastModified() ([]byte, string) {
func GetLastModified() *File {
lastModified.Lock()
defer lastModified.Unlock()
return lastModified.contents, lastModified.sha256
return &File{Content: lastModified.contents, Hash: lastModified.sha256}
}
// FilterResolvDNS cleans up the config in resolvConf. It has two main jobs:
@ -88,9 +111,7 @@ func GetLastModified() ([]byte, string) {
// 2. Given the caller provides the enable/disable state of IPv6, the filter
// code will remove all IPv6 nameservers if it is not enabled for containers
//
// It returns a boolean to notify the caller if changes were made at all
func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) ([]byte, bool) {
changed := false
func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) (*File, error) {
cleanedResolvConf := localhostNSRegexp.ReplaceAll(resolvConf, []byte{})
// if IPv6 is not enabled, also clean out any IPv6 address nameserver
if !ipv6Enabled {
@ -107,10 +128,11 @@ func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) ([]byte, bool) {
}
cleanedResolvConf = append(cleanedResolvConf, []byte("\n"+strings.Join(dns, "\n"))...)
}
if !bytes.Equal(resolvConf, cleanedResolvConf) {
changed = true
hash, err := ioutils.HashData(bytes.NewReader(cleanedResolvConf))
if err != nil {
return nil, err
}
return cleanedResolvConf, changed
return &File{Content: cleanedResolvConf, Hash: hash}, nil
}
// getLines parses input into lines and strips away comments.
@ -184,32 +206,32 @@ func GetOptions(resolvConf []byte) []string {
// Build writes a configuration file to path containing a "nameserver" entry
// for every element in dns, a "search" entry for every element in
// dnsSearch, and an "options" entry for every element in dnsOptions.
func Build(path string, dns, dnsSearch, dnsOptions []string) (string, error) {
func Build(path string, dns, dnsSearch, dnsOptions []string) (*File, error) {
content := bytes.NewBuffer(nil)
if len(dnsSearch) > 0 {
if searchString := strings.Join(dnsSearch, " "); strings.Trim(searchString, " ") != "." {
if _, err := content.WriteString("search " + searchString + "\n"); err != nil {
return "", err
return nil, err
}
}
}
for _, dns := range dns {
if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil {
return "", err
return nil, err
}
}
if len(dnsOptions) > 0 {
if optsString := strings.Join(dnsOptions, " "); strings.Trim(optsString, " ") != "" {
if _, err := content.WriteString("options " + optsString + "\n"); err != nil {
return "", err
return nil, err
}
}
}
hash, err := ioutils.HashData(bytes.NewReader(content.Bytes()))
if err != nil {
return "", err
return nil, err
}
return hash, ioutil.WriteFile(path, content.Bytes(), 0644)
return &File{Content: content.Bytes(), Hash: hash}, ioutil.WriteFile(path, content.Bytes(), 0644)
}

50
libnetwork/resolvconf/resolvconf_test.go
View file

@ -6,6 +6,7 @@ import (
"os"
"testing"
"github.com/docker/docker/pkg/ioutils"
_ "github.com/docker/libnetwork/netutils"
)
@ -18,9 +19,16 @@ func TestGet(t *testing.T) {
if err != nil {
t.Fatal(err)
}
if string(resolvConfUtils) != string(resolvConfSystem) {
if string(resolvConfUtils.Content) != string(resolvConfSystem) {
t.Fatalf("/etc/resolv.conf and GetResolvConf have different content.")
}
hashSystem, err := ioutils.HashData(bytes.NewReader(resolvConfSystem))
if err != nil {
t.Fatal(err)
}
if resolvConfUtils.Hash != hashSystem {
t.Fatalf("/etc/resolv.conf and GetResolvConf have different hashes.")
}
}
func TestGetNameservers(t *testing.T) {
@ -214,51 +222,51 @@ func TestFilterResolvDns(t *testing.T) {
ns0 := "nameserver 10.16.60.14\nnameserver 10.16.60.21\n"
if result, _ := FilterResolvDNS([]byte(ns0), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed No Localhost: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed No Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
ns1 := "nameserver 10.16.60.14\nnameserver 10.16.60.21\nnameserver 127.0.0.1\n"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
ns1 = "nameserver 10.16.60.14\nnameserver 127.0.0.1\nnameserver 10.16.60.21\n"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
ns1 = "nameserver 127.0.1.1\nnameserver 10.16.60.14\nnameserver 10.16.60.21\n"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
ns1 = "nameserver ::1\nnameserver 10.16.60.14\nnameserver 127.0.2.1\nnameserver 10.16.60.21\n"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
ns1 = "nameserver 10.16.60.14\nnameserver ::1\nnameserver 10.16.60.21\nnameserver ::1"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
// with IPv6 disabled (false param), the IPv6 nameserver should be removed
ns1 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\nnameserver ::1"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost+IPv6 off: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost+IPv6 off: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
@ -266,8 +274,8 @@ func TestFilterResolvDns(t *testing.T) {
ns0 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\n"
ns1 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\nnameserver ::1"
if result, _ := FilterResolvDNS([]byte(ns1), true); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed Localhost+IPv6 on: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed Localhost+IPv6 on: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
@ -275,8 +283,8 @@ func TestFilterResolvDns(t *testing.T) {
ns0 = "\nnameserver 8.8.8.8\nnameserver 8.8.4.4\nnameserver 2001:4860:4860::8888\nnameserver 2001:4860:4860::8844"
ns1 = "nameserver 127.0.0.1\nnameserver ::1\nnameserver 127.0.2.1"
if result, _ := FilterResolvDNS([]byte(ns1), true); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
@ -284,8 +292,8 @@ func TestFilterResolvDns(t *testing.T) {
ns0 = "\nnameserver 8.8.8.8\nnameserver 8.8.4.4"
ns1 = "nameserver 127.0.0.1\nnameserver ::1\nnameserver 127.0.2.1"
if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil {
if ns0 != string(result) {
t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result))
if ns0 != string(result.Content) {
t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result.Content))
}
}
}

78
libnetwork/sandbox.go
View file

@ -1,7 +1,6 @@
package libnetwork
import (
"bytes"
"container/heap"
"encoding/json"
"fmt"
@ -12,7 +11,6 @@ import (
"sync"
log "github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/ioutils"
"github.com/docker/libnetwork/etchosts"
"github.com/docker/libnetwork/osl"
"github.com/docker/libnetwork/resolvconf"
@ -339,6 +337,10 @@ func (sb *sandbox) buildHostsFile() error {
}
func (sb *sandbox) updateHostsFile(ifaceIP string, svcRecords []etchosts.Record) error {
if sb.config.originHostsPath != "" {
return nil
}
// Rebuild the hosts file accounting for the passed interface IP and service records
extraContent := make([]etchosts.Record, 0, len(sb.config.extraHosts)+len(svcRecords))
@ -382,6 +384,8 @@ func (sb *sandbox) updateParentHosts() error {
}
func (sb *sandbox) setupDNS() error {
var newRC *resolvconf.File
if sb.config.resolvConfPath == "" {
sb.config.resolvConfPath = defaultPrefix + "/" + sb.id + "/resolv.conf"
}
@ -401,15 +405,18 @@ func (sb *sandbox) setupDNS() error {
return nil
}
resolvConf, err := resolvconf.Get()
currRC, err := resolvconf.Get()
if err != nil {
return err
}
dnsList := resolvconf.GetNameservers(resolvConf)
dnsSearchList := resolvconf.GetSearchDomains(resolvConf)
dnsOptionsList := resolvconf.GetOptions(resolvConf)
if len(sb.config.dnsList) > 0 || len(sb.config.dnsSearchList) > 0 || len(dnsOptionsList) > 0 {
if len(sb.config.dnsList) > 0 || len(sb.config.dnsSearchList) > 0 || len(sb.config.dnsOptionsList) > 0 {
var (
err error
dnsList = resolvconf.GetNameservers(currRC.Content)
dnsSearchList = resolvconf.GetSearchDomains(currRC.Content)
dnsOptionsList = resolvconf.GetOptions(currRC.Content)
)
if len(sb.config.dnsList) > 0 {
dnsList = sb.config.dnsList
}
@ -419,47 +426,56 @@ func (sb *sandbox) setupDNS() error {
if len(sb.config.dnsOptionsList) > 0 {
dnsOptionsList = sb.config.dnsOptionsList
}
newRC, err = resolvconf.Build(sb.config.resolvConfPath, dnsList, dnsSearchList, dnsOptionsList)
if err != nil {
return err
}
} else {
// Replace any localhost/127.* (at this point we have no info about ipv6, pass it as true)
if newRC, err = resolvconf.FilterResolvDNS(currRC.Content, true); err != nil {
return err
}
// No contention on container resolv.conf file at sandbox creation
if err := ioutil.WriteFile(sb.config.resolvConfPath, newRC.Content, filePerm); err != nil {
return types.InternalErrorf("failed to write unhaltered resolv.conf file content when setting up dns for sandbox %s: %v", sb.ID(), err)
}
}
hash, err := resolvconf.Build(sb.config.resolvConfPath, dnsList, dnsSearchList, dnsOptionsList)
if err != nil {
return err
}
// write hash
if err := ioutil.WriteFile(sb.config.resolvConfHashFile, []byte(hash), filePerm); err != nil {
return types.InternalErrorf("failed to write resol.conf hash file when setting up dns for sandbox %s: %v", sb.ID(), err)
// Write hash
if err := ioutil.WriteFile(sb.config.resolvConfHashFile, []byte(newRC.Hash), filePerm); err != nil {
return types.InternalErrorf("failed to write resolv.conf hash file when setting up dns for sandbox %s: %v", sb.ID(), err)
}
return nil
}
func (sb *sandbox) updateDNS(ipv6Enabled bool) error {
var oldHash []byte
hashFile := sb.config.resolvConfHashFile
var (
currHash string
hashFile = sb.config.resolvConfHashFile
)
resolvConf, err := ioutil.ReadFile(sb.config.resolvConfPath)
if len(sb.config.dnsList) > 0 || len(sb.config.dnsSearchList) > 0 || len(sb.config.dnsOptionsList) > 0 {
return nil
}
currRC, err := resolvconf.GetSpecific(sb.config.resolvConfPath)
if err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
oldHash, err = ioutil.ReadFile(hashFile)
h, err := ioutil.ReadFile(hashFile)
if err != nil {
if !os.IsNotExist(err) {
return err
}
oldHash = []byte{}
} else {
currHash = string(h)
}
}
curHash, err := ioutils.HashData(bytes.NewReader(resolvConf))
if err != nil {
return err
}
if string(oldHash) != "" && curHash != string(oldHash) {
if currHash != "" && currHash != currRC.Hash {
// Seems the user has changed the container resolv.conf since the last time
// we checked so return without doing anything.
log.Infof("Skipping update of resolv.conf file with ipv6Enabled: %t because file was touched by user", ipv6Enabled)
@ -467,9 +483,7 @@ func (sb *sandbox) updateDNS(ipv6Enabled bool) error {
}
// replace any localhost/127.* and remove IPv6 nameservers if IPv6 disabled.
resolvConf, _ = resolvconf.FilterResolvDNS(resolvConf, ipv6Enabled)
newHash, err := ioutils.HashData(bytes.NewReader(resolvConf))
newRC, err := resolvconf.FilterResolvDNS(currRC.Content, ipv6Enabled)
if err != nil {
return err
}
@ -491,10 +505,10 @@ func (sb *sandbox) updateDNS(ipv6Enabled bool) error {
}
// write the updates to the temp files
if err = ioutil.WriteFile(tmpHashFile.Name(), []byte(newHash), filePerm); err != nil {
if err = ioutil.WriteFile(tmpHashFile.Name(), []byte(newRC.Hash), filePerm); err != nil {
return err
}
if err = ioutil.WriteFile(tmpResolvFile.Name(), resolvConf, filePerm); err != nil {
if err = ioutil.WriteFile(tmpResolvFile.Name(), newRC.Content, filePerm); err != nil {
return err
}