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kubeadm: Let the --node-name flag flow down to --hostname-override for the kubelet #64706

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merged 2 commits into from
Jun 5, 2018
Merged

kubeadm: Let the --node-name flag flow down to --hostname-override for the kubelet #64706

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3da1228
Bazel artefacts
liztio Jun 4, 2018
b42564a
Kubeadm-initialised kubelet uses provided hostname if present
liztio Jun 4, 2018
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3 changes: 3 additions & 0 deletions cmd/kubeadm/app/phases/kubelet/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ go_library(
"//pkg/apis/rbac/v1:go_default_library",
"//pkg/kubelet/apis/kubeletconfig/scheme:go_default_library",
"//pkg/kubelet/apis/kubeletconfig/v1beta1:go_default_library",
"//pkg/util/node:go_default_library",
"//pkg/util/procfs:go_default_library",
"//pkg/util/version:go_default_library",
"//vendor/github.com/golang/glog:go_default_library",
Expand All @@ -37,12 +38,14 @@ go_test(
srcs = [
"config_test.go",
"dynamic_test.go",
"flags_test.go",
],
embed = [":go_default_library"],
deps = [
"//cmd/kubeadm/app/apis/kubeadm:go_default_library",
"//pkg/kubelet/apis:go_default_library",
"//pkg/kubelet/apis/kubeletconfig/v1beta1:go_default_library",
"//pkg/util/node:go_default_library",
"//pkg/util/version:go_default_library",
"//vendor/k8s.io/api/core/v1:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
Expand Down
8 changes: 7 additions & 1 deletion cmd/kubeadm/app/phases/kubelet/flags.go
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Expand Up @@ -28,6 +28,7 @@ import (
kubeadmapiv1alpha2 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha2"
"k8s.io/kubernetes/cmd/kubeadm/app/constants"
kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
nodeutil "k8s.io/kubernetes/pkg/util/node"
"k8s.io/kubernetes/pkg/util/procfs"
utilsexec "k8s.io/utils/exec"
)
Expand Down Expand Up @@ -78,7 +79,12 @@ func buildKubeletArgMap(nodeRegOpts *kubeadmapi.NodeRegistrationOptions, registe
kubeletFlags["resolv-conf"] = "/run/systemd/resolve/resolv.conf"
}

// TODO: Pass through --hostname-override if a custom name is used?
// Make sure the node name we're passed will work with Kubelet
if nodeRegOpts.Name != "" && nodeRegOpts.Name != nodeutil.GetHostname("") {
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given that the most common thing folks do is use fully qualified domain names I'm almost wondering if we should force tolower on the names similar to your other patch.

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I just tested this, and it appears this already happens automatically:

ubuntu@ip-172-31-84-104:~$ sudo /tmp/kubeadm init -v 1 --pod-network-cidr=192.168.0.0/16 --node-name ALLCAPS.horse

ubuntu@ip-172-31-84-104:~$ kubectl get nodes
NAME            STATUS    ROLES     AGE       VERSION
allcaps.horse   Ready     master    44s       v1.11.0-beta.0

I don't particularly know how, but I think this is a nonissue either way.

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The nodeutil.GetHostname() func lowercases automatically:

// GetHostname returns OS's hostname if 'hostnameOverride' is empty; otherwise, return 'hostnameOverride'.
func GetHostname(hostnameOverride string) string {
	hostname := hostnameOverride
	if hostname == "" {
		nodename, err := os.Hostname()
		if err != nil {
			glog.Fatalf("Couldn't determine hostname: %v", err)
		}
		hostname = nodename
	}
	return strings.ToLower(strings.TrimSpace(hostname))
}

glog.V(1).Info("setting kubelet hostname-override to %q", nodeRegOpts.Name)
kubeletFlags["hostname-override"] = nodeRegOpts.Name
}

// TODO: Conditionally set `--cgroup-driver` to either `systemd` or `cgroupfs` for CRI other than Docker

return kubeletFlags
Expand Down
62 changes: 62 additions & 0 deletions cmd/kubeadm/app/phases/kubelet/flags_test.go
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@@ -0,0 +1,62 @@
/*
Copyright 2018 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 kubelet

import (
"testing"

kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
nodeutil "k8s.io/kubernetes/pkg/util/node"
)

func TestBuildKubeletArgMap(t *testing.T) {

tests := []struct {
name string
hostname string
expectedHostname string
}{
{
name: "manually set to current hostname",
hostname: nodeutil.GetHostname(""),
expectedHostname: "",
},
{
name: "unset hostname",
hostname: "",
expectedHostname: "",
},
{
name: "override hostname",
hostname: "my-node",
expectedHostname: "my-node",
},
}

for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
opts := &kubeadmapi.NodeRegistrationOptions{
Name: test.hostname,
}

m := buildKubeletArgMap(opts, false)
if m["hostname-override"] != test.expectedHostname {
t.Errorf("expected hostname %q, got %q", test.expectedHostname, m["hostname-override"])
}
})
}
}