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Adding Kubelet changes to enable SetHostnameAsFQDN feature

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These changes allow to set FQDN as hostname of pods for pods
that set the new PodSpec field setHostnameAsFQDN to true. The PodSpec
new field was added in related PR.

This is PART2 (last) of the changes to enable KEP #1797 and addresses #91036
This commit is contained in:
Javier Diaz-Montes 2020-06-01 17:10:54 -04:00
parent 7ef7ce2a3c
commit 9743cda4a7
6 changed files with 266 additions and 4 deletions
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11
pkg/kubelet/kubelet_pods.go
View File

@ -58,6 +58,7 @@ import (
"k8s.io/kubernetes/pkg/kubelet/images"
"k8s.io/kubernetes/pkg/kubelet/status"
kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
"k8s.io/kubernetes/pkg/kubelet/util"
"k8s.io/kubernetes/pkg/kubelet/util/format"
volumeutil "k8s.io/kubernetes/pkg/volume/util"
"k8s.io/kubernetes/pkg/volume/util/hostutil"
@ -442,12 +443,18 @@ func (kl *Kubelet) GenerateRunContainerOptions(pod *v1.Pod, container *v1.Contai
if err != nil {
return nil, nil, err
}
// The value of hostname is the short host name and it is sent to makeMounts to create /etc/hosts file.
hostname, hostDomainName, err := kl.GeneratePodHostNameAndDomain(pod)
if err != nil {
return nil, nil, err
}
opts.Hostname = hostname
// nodename will be equals to hostname if SetHostnameAsFQDN is nil or false. If SetHostnameFQDN
// is true and hostDomainName is defined, nodename will be the FQDN (hostname.hostDomainName)
nodename, err := util.GetNodenameForKernel(hostname, hostDomainName, pod.Spec.SetHostnameAsFQDN)
if err != nil {
return nil, nil, err
}
opts.Hostname = nodename
podName := volumeutil.GetUniquePodName(pod)
volumes := kl.volumeManager.GetMountedVolumesForPod(podName)

9
pkg/kubelet/kuberuntime/kuberuntime_sandbox.go
View File

@ -30,6 +30,7 @@ import (
"k8s.io/kubernetes/pkg/features"
kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
"k8s.io/kubernetes/pkg/kubelet/types"
"k8s.io/kubernetes/pkg/kubelet/util"
"k8s.io/kubernetes/pkg/kubelet/util/format"
)
@ -96,11 +97,15 @@ func (m *kubeGenericRuntimeManager) generatePodSandboxConfig(pod *v1.Pod, attemp
if !kubecontainer.IsHostNetworkPod(pod) {
// TODO: Add domain support in new runtime interface
hostname, _, err := m.runtimeHelper.GeneratePodHostNameAndDomain(pod)
podHostname, podDomain, err := m.runtimeHelper.GeneratePodHostNameAndDomain(pod)
if err != nil {
return nil, err
}
podSandboxConfig.Hostname = hostname
podHostname, err = util.GetNodenameForKernel(podHostname, podDomain, pod.Spec.SetHostnameAsFQDN)
if err != nil {
return nil, err
}
podSandboxConfig.Hostname = podHostname
}
logDir := BuildPodLogsDirectory(pod.Namespace, pod.Name, pod.UID)

18
pkg/kubelet/util/util.go
View File

@ -17,6 +17,8 @@ limitations under the License.
package util
import (
"fmt"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)
@ -25,3 +27,19 @@ import (
func FromApiserverCache(opts *metav1.GetOptions) {
opts.ResourceVersion = "0"
}
// GetNodenameForKernel gets hostname value to set in the hostname field (the nodename field of struct utsname) of the pod.
func GetNodenameForKernel(hostname string, hostDomainName string, setHostnameAsFQDN *bool) (string, error) {
kernelHostname := hostname
// FQDN has to be 64 chars to fit in the Linux nodename kernel field (specification 64 chars and the null terminating char).
const fqdnMaxLen = 64
if len(hostDomainName) > 0 && setHostnameAsFQDN != nil && *setHostnameAsFQDN == true {
fqdn := fmt.Sprintf("%s.%s", hostname, hostDomainName)
// FQDN has to be shorter than hostnameMaxLen characters.
if len(fqdn) > fqdnMaxLen {
return "", fmt.Errorf("Failed to construct FQDN from pod hostname and cluster domain, FQDN %s is too long (%d characters is the max, %d characters requested)", fqdn, fqdnMaxLen, len(fqdn))
}
kernelHostname = fqdn
}
return kernelHostname, nil
}

88
pkg/kubelet/util/util_test.go Normal file
View File

@ -0,0 +1,88 @@
/*
Copyright 2020 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package util
import (
"testing"
"github.com/stretchr/testify/assert"
)
func TestGetNodenameForKernel(t *testing.T) {
testcases := []struct {
description string
hostname string
hostDomain string
setHostnameAsFQDN bool
expectedHostname string
expectError bool
}{{
description: "no hostDomain, setHostnameAsFQDN false",
hostname: "test.pod.hostname",
hostDomain: "",
setHostnameAsFQDN: false,
expectedHostname: "test.pod.hostname",
expectError: false,
}, {
description: "no hostDomain, setHostnameAsFQDN true",
hostname: "test.pod.hostname",
hostDomain: "",
setHostnameAsFQDN: true,
expectedHostname: "test.pod.hostname",
expectError: false,
}, {
description: "valid hostDomain, setHostnameAsFQDN false",
hostname: "test.pod.hostname",
hostDomain: "svc.subdomain.local",
setHostnameAsFQDN: false,
expectedHostname: "test.pod.hostname",
expectError: false,
}, {
description: "valid hostDomain, setHostnameAsFQDN true",
hostname: "test.pod.hostname",
hostDomain: "svc.subdomain.local",
setHostnameAsFQDN: true,
expectedHostname: "test.pod.hostname.svc.subdomain.local",
expectError: false,
}, {
description: "FQDN is too long, setHostnameAsFQDN false",
hostname: "1234567.1234567", //8*2-1=15 chars
hostDomain: "1234567.1234567.1234567.1234567.1234567.1234567.1234567", //8*7-1=55 chars
setHostnameAsFQDN: false, //FQDN=15 + 1(dot) + 55 = 71 chars
expectedHostname: "1234567.1234567",
expectError: false,
}, {
description: "FQDN is too long, setHostnameAsFQDN true",
hostname: "1234567.1234567", //8*2-1=15 chars
hostDomain: "1234567.1234567.1234567.1234567.1234567.1234567.1234567", //8*7-1=55 chars
setHostnameAsFQDN: true, //FQDN=15 + 1(dot) + 55 = 71 chars
expectedHostname: "",
expectError: true,
}}
for _, tc := range testcases {
t.Logf("TestCase: %q", tc.description)
outputHostname, err := GetNodenameForKernel(tc.hostname, tc.hostDomain, &tc.setHostnameAsFQDN)
if tc.expectError {
assert.Error(t, err)
} else {
assert.NoError(t, err)
}
assert.Equal(t, tc.expectedHostname, outputHostname)
}
}

1
test/e2e/node/BUILD
View File

@ -12,6 +12,7 @@ go_library(
"mount_propagation.go",
"node_problem_detector.go",
"pod_gc.go",
"pod_hostnamefqdn.go",
"pods.go",
"pre_stop.go",
"runtimeclass.go",

143
test/e2e/node/pod_hostnamefqdn.go Normal file
View File

@ -0,0 +1,143 @@
/*
Copyright 2020 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
/* This test check that setHostnameAsFQDN PodSpec field works as
* expected.
*/
package node
import (
"crypto/rand"
"fmt"
"math/big"
v1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/kubernetes/test/e2e/framework"
imageutils "k8s.io/kubernetes/test/utils/image"
"github.com/onsi/ginkgo"
)
func generatePodName(base string) string {
id, err := rand.Int(rand.Reader, big.NewInt(214748))
if err != nil {
return base
}
return fmt.Sprintf("%s-%d", base, id)
}
func testPod() *v1.Pod {
podName := generatePodName("hostfqdn")
pod := &v1.Pod{
ObjectMeta: metav1.ObjectMeta{
Name: podName,
Labels: map[string]string{"name": podName},
Annotations: map[string]string{},
},
Spec: v1.PodSpec{
Containers: []v1.Container{
{
Name: "test-container",
Image: imageutils.GetE2EImage(imageutils.BusyBox),
},
},
RestartPolicy: v1.RestartPolicyNever,
},
}
return pod
}
var _ = SIGDescribe("Hostname of Pod [Feature:SetHostnameAsFQDN]", func() {
f := framework.NewDefaultFramework("hostfqdn")
/*
Release : v1.19
Testname: Create Pod without fully qualified domain name (FQDN)
Description: A Pod that does not define the subdomain field in it spec, does not have FQDN.
*/
ginkgo.It("a pod without subdomain field does not have FQDN [Feature:SetHostnameAsFQDN]", func() {
pod := testPod()
pod.Spec.Containers[0].Command = []string{"sh", "-c", "echo $(hostname)';'$(hostname -f)';'"}
output := []string{fmt.Sprintf("%s;%s;", pod.ObjectMeta.Name, pod.ObjectMeta.Name)}
// Create Pod
f.TestContainerOutput("shotname only", pod, 0, output)
})
/*
Release : v1.19
Testname: Create Pod without FQDN, setHostnameAsFQDN field set to true
Description: A Pod that does not define the subdomain field in it spec, does not have FQDN.
Hence, SetHostnameAsFQDN feature has no effect.
*/
ginkgo.It("a pod without FQDN is not affected by SetHostnameAsFQDN field [Feature:SetHostnameAsFQDN]", func() {
pod := testPod()
// Setting setHostnameAsFQDN field to true should have no effect.
setHostnameAsFQDN := true
pod.Spec.SetHostnameAsFQDN = &setHostnameAsFQDN
pod.Spec.Containers[0].Command = []string{"sh", "-c", "echo $(hostname)';'$(hostname -f)';'"}
output := []string{fmt.Sprintf("%s;%s;", pod.ObjectMeta.Name, pod.ObjectMeta.Name)}
// Create Pod
f.TestContainerOutput("shotname only", pod, 0, output)
})
/*
Release : v1.19
Testname: Create Pod with FQDN, setHostnameAsFQDN field not defined.
Description: A Pod that defines the subdomain field in it spec has FQDN.
hostname command returns shortname (pod name in this case), and hostname -f returns FQDN.
*/
ginkgo.It("a pod with subdomain field has FQDN, hostname is shortname [Feature:SetHostnameAsFQDN]", func() {
pod := testPod()
pod.Spec.Containers[0].Command = []string{"sh", "-c", "echo $(hostname)';'$(hostname -f)';'"}
subdomain := "t"
// Set PodSpec subdomain field to generate FQDN for pod
pod.Spec.Subdomain = subdomain
// Expected Pod FQDN
hostFQDN := fmt.Sprintf("%s.%s.%s.svc.%s", pod.ObjectMeta.Name, subdomain, f.Namespace.Name, framework.TestContext.ClusterDNSDomain)
output := []string{fmt.Sprintf("%s;%s;", pod.ObjectMeta.Name, hostFQDN)}
// Create Pod
f.TestContainerOutput("shotname and fqdn", pod, 0, output)
})
/*
Release : v1.19
Testname: Create Pod with FQDN, setHostnameAsFQDN field set to true.
Description: A Pod that defines the subdomain field in it spec has FQDN. When setHostnameAsFQDN: true, the
hostname is set to be the FQDN. In this case, both commands hostname and hostname -f return the FQDN of the Pod.
*/
ginkgo.It("a pod with subdomain field has FQDN, when setHostnameAsFQDN is set to true, the FQDN is set as hostname [Feature:SetHostnameAsFQDN]", func() {
pod := testPod()
pod.Spec.Containers[0].Command = []string{"sh", "-c", "echo $(hostname)';'$(hostname -f)';'"}
subdomain := "t"
// Set PodSpec subdomain field to generate FQDN for pod
pod.Spec.Subdomain = subdomain
// Set PodSpec setHostnameAsFQDN to set FQDN as hostname
setHostnameAsFQDN := true
pod.Spec.SetHostnameAsFQDN = &setHostnameAsFQDN
// Expected Pod FQDN
hostFQDN := fmt.Sprintf("%s.%s.%s.svc.%s", pod.ObjectMeta.Name, subdomain, f.Namespace.Name, framework.TestContext.ClusterDNSDomain)
// Fail if FQDN is longer than 64 characters, otherwise the Pod will remain pending until test timeout.
// In Linux, 64 characters is the limit of the hostname kernel field, which this test sets to the pod FQDN.
framework.ExpectEqual(len(hostFQDN) < 65, true, fmt.Sprintf("The FQDN of the Pod cannot be longer than 64 characters, requested %s which is %d characters long.", hostFQDN, len(hostFQDN)))
output := []string{fmt.Sprintf("%s;%s;", hostFQDN, hostFQDN)}
// Create Pod
f.TestContainerOutput("fqdn and fqdn", pod, 0, output)
})
})