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Merge pull request #54773 from phsiao/dns_options_handling 

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Support copying "options" in resolv.conf into pod sandbox when dnsPolicy is Default

**What this PR does / why we need it**:

This PR adds support for copying "options" from host's /etc/resolv.conf (or --resolv-conf) into pod's resolv.conf when dnsPolicy is Default.  Being able to customize options is important because it is common to leverage options to fine-tune the behavior of DNS client.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #42542

**Special notes for your reviewer**:

I originally wanted to also tackle the issue of copying options for when dnsPolicy is ClusterFirst, but with ability to "merge" with default options (ndots:5 more specifically) when it makes sense.  I decided to leave it off for now because the "merging" may need more discussions.   Happy to add that to this PR or create another PR for that if it makes sense and is clear what should be done.   I think even when dnsPolicy is ClusterFirst it is important to allow customization.

**Release note**:

```kubelet: add support for copying "options" from /etc/resolv.conf (or --resolv-conf if it is used) into pod's /etc/resolv.conf when dnsPolicy is Default.```
pull/6/head
Kubernetes Submit Queue 2017-11-08 22:08:24 -08:00 committed by GitHub
parent a8b355cf92 5cba1f47c3
commit 3b359fb675
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GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 60 additions and 46 deletions
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2
pkg/kubelet/container/helpers.go
View File

@ -47,7 +47,7 @@ type HandlerRunner interface {
// able to get necessary informations like the RunContainerOptions, DNS settings, Host IP.
type RuntimeHelper interface {
GenerateRunContainerOptions(pod *v1.Pod, container *v1.Container, podIP string) (contOpts *RunContainerOptions, err error)
GetClusterDNS(pod *v1.Pod) (dnsServers []string, dnsSearches []string, useClusterFirstPolicy bool, err error)
GetClusterDNS(pod *v1.Pod) (dnsServers []string, dnsSearches []string, dnsOptions []string, useClusterFirstPolicy bool, err error)
// GetPodCgroupParent returns the CgroupName identifer, and its literal cgroupfs form on the host
// of a pod.
GetPodCgroupParent(pod *v1.Pod) string

4
pkg/kubelet/container/testing/fake_runtime_helper.go
View File

@ -44,8 +44,8 @@ func (f *FakeRuntimeHelper) GetPodCgroupParent(pod *v1.Pod) string {
return ""
}
func (f *FakeRuntimeHelper) GetClusterDNS(pod *v1.Pod) ([]string, []string, bool, error) {
return f.DNSServers, f.DNSSearches, false, f.Err
func (f *FakeRuntimeHelper) GetClusterDNS(pod *v1.Pod) ([]string, []string, []string, bool, error) {
return f.DNSServers, f.DNSSearches, nil, false, f.Err
}
// This is not used by docker runtime.

20
pkg/kubelet/kubelet.go
View File

@ -1401,21 +1401,21 @@ func (kl *Kubelet) GetKubeClient() clientset.Interface {
return kl.kubeClient
}
// GetClusterDNS returns a list of the DNS servers and a list of the DNS search
// domains of the cluster.
func (kl *Kubelet) GetClusterDNS(pod *v1.Pod) ([]string, []string, bool, error) {
var hostDNS, hostSearch []string
// GetClusterDNS returns a list of the DNS servers, a list of the DNS search
// domains of the cluster, and a list of resolv.conf options.
func (kl *Kubelet) GetClusterDNS(pod *v1.Pod) ([]string, []string, []string, bool, error) {
var hostDNS, hostSearch, hostOptions []string
// Get host DNS settings
if kl.resolverConfig != "" {
f, err := os.Open(kl.resolverConfig)
if err != nil {
return nil, nil, false, err
return nil, nil, nil, false, err
}
defer f.Close()
hostDNS, hostSearch, err = kl.parseResolvConf(f)
hostDNS, hostSearch, hostOptions, err = kl.parseResolvConf(f)
if err != nil {
return nil, nil, false, err
return nil, nil, nil, false, err
}
}
useClusterFirstPolicy := ((pod.Spec.DNSPolicy == v1.DNSClusterFirst && !kubecontainer.IsHostNetworkPod(pod)) || pod.Spec.DNSPolicy == v1.DNSClusterFirstWithHostNet)
@ -1444,7 +1444,7 @@ func (kl *Kubelet) GetClusterDNS(pod *v1.Pod) ([]string, []string, bool, error)
} else {
hostSearch = kl.formDNSSearchForDNSDefault(hostSearch, pod)
}
return hostDNS, hostSearch, useClusterFirstPolicy, nil
return hostDNS, hostSearch, hostOptions, useClusterFirstPolicy, nil
}
// for a pod with DNSClusterFirst policy, the cluster DNS server is the only nameserver configured for
@ -1456,7 +1456,7 @@ func (kl *Kubelet) GetClusterDNS(pod *v1.Pod) ([]string, []string, bool, error)
}
dnsSearch := kl.formDNSSearch(hostSearch, pod)
return dns, dnsSearch, useClusterFirstPolicy, nil
return dns, dnsSearch, hostOptions, useClusterFirstPolicy, nil
}
// syncPod is the transaction script for the sync of a single pod.
@ -2237,7 +2237,7 @@ func (kl *Kubelet) setupDNSinContainerizedMounter(mounterPath string) {
if err != nil {
glog.Error("Could not open resolverConf file")
} else {
_, hostSearch, err := kl.parseResolvConf(f)
_, hostSearch, _, err := kl.parseResolvConf(f)
if err != nil {
glog.Errorf("Error for parsing the reslov.conf file: %v", err)
} else {

17
pkg/kubelet/kubelet_network.go
View File

@ -169,7 +169,7 @@ func (kl *Kubelet) checkLimitsForResolvConf() {
}
defer f.Close()
_, hostSearch, err := kl.parseResolvConf(f)
_, hostSearch, _, err := kl.parseResolvConf(f)
if err != nil {
kl.recorder.Event(kl.nodeRef, v1.EventTypeWarning, "checkLimitsForResolvConf", err.Error())
glog.Error("checkLimitsForResolvConf: " + err.Error())
@ -200,12 +200,12 @@ func (kl *Kubelet) checkLimitsForResolvConf() {
}
// parseResolveConf reads a resolv.conf file from the given reader, and parses
// it into nameservers and searches, possibly returning an error.
// it into nameservers, searches and options, possibly returning an error.
// TODO: move to utility package
func (kl *Kubelet) parseResolvConf(reader io.Reader) (nameservers []string, searches []string, err error) {
func (kl *Kubelet) parseResolvConf(reader io.Reader) (nameservers []string, searches []string, options []string, err error) {
file, err := ioutil.ReadAll(reader)
if err != nil {
return nil, nil, err
return nil, nil, nil, err
}
// Lines of the form "nameserver 1.2.3.4" accumulate.
@ -214,6 +214,10 @@ func (kl *Kubelet) parseResolvConf(reader io.Reader) (nameservers []string, sear
// Lines of the form "search example.com" overrule - last one wins.
searches = []string{}
// Lines of the form "option ndots:5 attempts:2" overrule - last one wins.
// Each option is recorded as an element in the array.
options = []string{}
lines := strings.Split(string(file), "\n")
for l := range lines {
trimmed := strings.TrimSpace(lines[l])
@ -230,13 +234,16 @@ func (kl *Kubelet) parseResolvConf(reader io.Reader) (nameservers []string, sear
if fields[0] == "search" {
searches = fields[1:]
}
if fields[0] == "options" {
options = fields[1:]
}
}
// There used to be code here to scrub DNS for each cloud, but doesn't
// make sense anymore since cloudproviders are being factored out.
// contact @thockin or @wlan0 for more information
return nameservers, searches, nil
return nameservers, searches, options, nil
}
// syncNetworkStatus updates the network state

53
pkg/kubelet/kubelet_network_test.go
View File

@ -74,39 +74,44 @@ func TestParseResolvConf(t *testing.T) {
data string
nameservers []string
searches []string
options []string
}{
{"", []string{}, []string{}},
{" ", []string{}, []string{}},
{"\n", []string{}, []string{}},
{"\t\n\t", []string{}, []string{}},
{"#comment\n", []string{}, []string{}},
{" #comment\n", []string{}, []string{}},
{"#comment\n#comment", []string{}, []string{}},
{"#comment\nnameserver", []string{}, []string{}},
{"#comment\nnameserver\nsearch", []string{}, []string{}},
{"nameserver 1.2.3.4", []string{"1.2.3.4"}, []string{}},
{" nameserver 1.2.3.4", []string{"1.2.3.4"}, []string{}},
{"\tnameserver 1.2.3.4", []string{"1.2.3.4"}, []string{}},
{"nameserver\t1.2.3.4", []string{"1.2.3.4"}, []string{}},
{"nameserver \t 1.2.3.4", []string{"1.2.3.4"}, []string{}},
{"nameserver 1.2.3.4\nnameserver 5.6.7.8", []string{"1.2.3.4", "5.6.7.8"}, []string{}},
{"nameserver 1.2.3.4 #comment", []string{"1.2.3.4"}, []string{}},
{"search foo", []string{}, []string{"foo"}},
{"search foo bar", []string{}, []string{"foo", "bar"}},
{"search foo bar bat\n", []string{}, []string{"foo", "bar", "bat"}},
{"search foo\nsearch bar", []string{}, []string{"bar"}},
{"nameserver 1.2.3.4\nsearch foo bar", []string{"1.2.3.4"}, []string{"foo", "bar"}},
{"nameserver 1.2.3.4\nsearch foo\nnameserver 5.6.7.8\nsearch bar", []string{"1.2.3.4", "5.6.7.8"}, []string{"bar"}},
{"#comment\nnameserver 1.2.3.4\n#comment\nsearch foo\ncomment", []string{"1.2.3.4"}, []string{"foo"}},
{"", []string{}, []string{}, []string{}},
{" ", []string{}, []string{}, []string{}},
{"\n", []string{}, []string{}, []string{}},
{"\t\n\t", []string{}, []string{}, []string{}},
{"#comment\n", []string{}, []string{}, []string{}},
{" #comment\n", []string{}, []string{}, []string{}},
{"#comment\n#comment", []string{}, []string{}, []string{}},
{"#comment\nnameserver", []string{}, []string{}, []string{}},
{"#comment\nnameserver\nsearch", []string{}, []string{}, []string{}},
{"nameserver 1.2.3.4", []string{"1.2.3.4"}, []string{}, []string{}},
{" nameserver 1.2.3.4", []string{"1.2.3.4"}, []string{}, []string{}},
{"\tnameserver 1.2.3.4", []string{"1.2.3.4"}, []string{}, []string{}},
{"nameserver\t1.2.3.4", []string{"1.2.3.4"}, []string{}, []string{}},
{"nameserver \t 1.2.3.4", []string{"1.2.3.4"}, []string{}, []string{}},
{"nameserver 1.2.3.4\nnameserver 5.6.7.8", []string{"1.2.3.4", "5.6.7.8"}, []string{}, []string{}},
{"nameserver 1.2.3.4 #comment", []string{"1.2.3.4"}, []string{}, []string{}},
{"search foo", []string{}, []string{"foo"}, []string{}},
{"search foo bar", []string{}, []string{"foo", "bar"}, []string{}},
{"search foo bar bat\n", []string{}, []string{"foo", "bar", "bat"}, []string{}},
{"search foo\nsearch bar", []string{}, []string{"bar"}, []string{}},
{"nameserver 1.2.3.4\nsearch foo bar", []string{"1.2.3.4"}, []string{"foo", "bar"}, []string{}},
{"nameserver 1.2.3.4\nsearch foo\nnameserver 5.6.7.8\nsearch bar", []string{"1.2.3.4", "5.6.7.8"}, []string{"bar"}, []string{}},
{"#comment\nnameserver 1.2.3.4\n#comment\nsearch foo\ncomment", []string{"1.2.3.4"}, []string{"foo"}, []string{}},
{"options ndots:5 attempts:2", []string{}, []string{}, []string{"ndots:5", "attempts:2"}},
{"options ndots:1\noptions ndots:5 attempts:3", []string{}, []string{}, []string{"ndots:5", "attempts:3"}},
{"nameserver 1.2.3.4\nsearch foo\nnameserver 5.6.7.8\nsearch bar\noptions ndots:5 attempts:4", []string{"1.2.3.4", "5.6.7.8"}, []string{"bar"}, []string{"ndots:5", "attempts:4"}},
}
testKubelet := newTestKubelet(t, false /* controllerAttachDetachEnabled */)
defer testKubelet.Cleanup()
kubelet := testKubelet.kubelet
for i, tc := range testCases {
ns, srch, err := kubelet.parseResolvConf(strings.NewReader(tc.data))
ns, srch, opts, err := kubelet.parseResolvConf(strings.NewReader(tc.data))
require.NoError(t, err)
assert.EqualValues(t, tc.nameservers, ns, "test case [%d]: name servers", i)
assert.EqualValues(t, tc.searches, srch, "test case [%d] searches", i)
assert.EqualValues(t, tc.options, opts, "test case [%d] options", i)
}
}

4
pkg/kubelet/kubelet_test.go
View File

@ -2194,7 +2194,7 @@ func TestGetClusterDNS(t *testing.T) {
}, 4)
for i, pod := range pods {
var err error
options[i].DNS, options[i].DNSSearch, _, err = kubelet.GetClusterDNS(pod)
options[i].DNS, options[i].DNSSearch, _, _, err = kubelet.GetClusterDNS(pod)
if err != nil {
t.Fatalf("failed to generate container options: %v", err)
}
@ -2227,7 +2227,7 @@ func TestGetClusterDNS(t *testing.T) {
kubelet.resolverConfig = "/etc/resolv.conf"
for i, pod := range pods {
var err error
options[i].DNS, options[i].DNSSearch, _, err = kubelet.GetClusterDNS(pod)
options[i].DNS, options[i].DNSSearch, _, _, err = kubelet.GetClusterDNS(pod)
if err != nil {
t.Fatalf("failed to generate container options: %v", err)
}

4
pkg/kubelet/kuberuntime/kuberuntime_sandbox.go
View File

@ -74,14 +74,16 @@ func (m *kubeGenericRuntimeManager) generatePodSandboxConfig(pod *v1.Pod, attemp
Annotations: newPodAnnotations(pod),
}
dnsServers, dnsSearches, useClusterFirstPolicy, err := m.runtimeHelper.GetClusterDNS(pod)
dnsServers, dnsSearches, dnsOptions, useClusterFirstPolicy, err := m.runtimeHelper.GetClusterDNS(pod)
if err != nil {
return nil, err
}
podSandboxConfig.DnsConfig = &runtimeapi.DNSConfig{
Servers: dnsServers,
Searches: dnsSearches,
Options: dnsOptions,
}
if useClusterFirstPolicy {
podSandboxConfig.DnsConfig.Options = defaultDNSOptions
}

2
pkg/kubelet/rkt/rkt.go
View File

@ -1041,7 +1041,7 @@ func (r *Runtime) generateRunCommand(pod *v1.Pod, uuid, networkNamespaceID strin
}
} else {
// Setup DNS.
dnsServers, dnsSearches, _, err := r.runtimeHelper.GetClusterDNS(pod)
dnsServers, dnsSearches, _, _, err := r.runtimeHelper.GetClusterDNS(pod)
if err != nil {
return "", err
}