おうちKubernetesをはじめる(その3)

はじめに
クラスタ構築
(参考)Kubenetesの理解を深める
参考にしたサイト
おわりに

はじめに

クラスタ構築

kubeadm init (マスターノードで実行)

コントロールプレーンの初期化をします。下記コマンドを実行します。

sudo kubeadm init

下記が実行結果です。

wurly@k8s1:~$ sudo kubeadm init
I0203 16:34:26.708499   23499 version.go:256] remote version is much newer: v1.29.1; falling back to: stable-1.28
[init] Using Kubernetes version: v1.28.6

(中略)

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.201:6443 --token mu8v4r.5e7v4uibqkplwmxx \
    --discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960

コマンド実行後に出力されたテキストには、内部で実行されたログと、この後に行うべきアクションが含まれます。

まず、指示通りこちらを実行します。

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

ここで、nodesの状態は下記のようになっており、ワーカーノードはまだ参加していない状態です。

wurly@k8s1:~$ kubectl get nodes
NAME   STATUS     ROLES           AGE     VERSION
k8s1   NotReady   control-plane   4m25s   v1.28.2

Calico のインストール (マスターノードで実行)

You should now deploy a pod network to the cluster. Run “kubectl apply -f [podnetwork].yaml” with one of the options listed at: https://kubernetes.io/docs/concepts/cluster-administration/addons/

次に、下記のリストからいずれかの “Networking and Network Policy” をインストールする必要があります。

https://kubernetes.io/docs/concepts/cluster-administration/addons/

数多くの選択肢がありますが、多くの手順書の内容を見習い、calico をインストールします。

インストール前のpodの状態です。

wurly@k8s1:~$ kubectl get pods -n kube-system
NAME                           READY   STATUS    RESTARTS   AGE
coredns-5dd5756b68-2dfmx       0/1     Pending   0          7m32s
coredns-5dd5756b68-z2pxd       0/1     Pending   0          7m32s
etcd-k8s1                      1/1     Running   0          7m37s
kube-apiserver-k8s1            1/1     Running   0          7m36s
kube-controller-manager-k8s1   1/1     Running   0          7m35s
kube-proxy-kkv4r               1/1     Running   0          7m32s
kube-scheduler-k8s1            1/1     Running   0          7m37s

実行するコマンドは下記です。

kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/calico.yaml

実行結果は下記の通りです。

wurly@k8s1:~$ kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/calico.yaml
poddisruptionbudget.policy/calico-kube-controllers created
serviceaccount/calico-kube-controllers created
serviceaccount/calico-node created
configmap/calico-config created
customresourcedefinition.apiextensions.k8s.io/bgpconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/bgppeers.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/blockaffinities.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/caliconodestatuses.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/clusterinformations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/felixconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/globalnetworkpolicies.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/globalnetworksets.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/hostendpoints.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamblocks.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamconfigs.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipamhandles.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ippools.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/ipreservations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/kubecontrollersconfigurations.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/networkpolicies.crd.projectcalico.org created
customresourcedefinition.apiextensions.k8s.io/networksets.crd.projectcalico.org created
clusterrole.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrole.rbac.authorization.k8s.io/calico-node created
clusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers created
clusterrolebinding.rbac.authorization.k8s.io/calico-node created
daemonset.apps/calico-node created
deployment.apps/calico-kube-controllers created

直後に確認したところ calico-node が生成中でした。

wurly@k8s1:~$ kubectl get pods -n kube-system
NAME                                       READY   STATUS     RESTARTS   AGE
calico-kube-controllers-658d97c59c-gjb8r   0/1     Pending    0          30s
calico-node-fhglf                          0/1     Init:1/3   0          30s
coredns-5dd5756b68-2dfmx                   0/1     Pending    0          9m42s
coredns-5dd5756b68-z2pxd                   0/1     Pending    0          9m42s
etcd-k8s1                                  1/1     Running    0          9m47s
kube-apiserver-k8s1                        1/1     Running    0          9m46s
kube-controller-manager-k8s1               1/1     Running    0          9m45s
kube-proxy-kkv4r                           1/1     Running    0          9m42s
kube-scheduler-k8s1                        1/1     Running    0          9m47s

しばらく待つとpodが立ち上がります。

wurly@k8s1:~$ kubectl get pods -n kube-system
NAME                                       READY   STATUS    RESTARTS   AGE
calico-kube-controllers-658d97c59c-gjb8r   1/1     Running   0          115s
calico-node-fhglf                          1/1     Running   0          115s
coredns-5dd5756b68-2dfmx                   1/1     Running   0          11m
coredns-5dd5756b68-z2pxd                   1/1     Running   0          11m
etcd-k8s1                                  1/1     Running   0          11m
kube-apiserver-k8s1                        1/1     Running   0          11m
kube-controller-manager-k8s1               1/1     Running   0          11m
kube-proxy-kkv4r                           1/1     Running   0          11m
kube-scheduler-k8s1                        1/1     Running   0          11m

kubeadm join (ワーカーノードで実行)

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.201:6443 –token mu8v4r.5e7v4uibqkplwmxx \ –discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960

マスターノードに出力されたメッセージに基づき、ワーカーノードとなるマシン側で kubeadm join を実行します。

wurly@k8s2:~$ kubeadm join 192.168.1.201:6443 --token mu8v4r.5e7v4uibqkplwmxx \
    --discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960 
> accepts at most 1 arg(s), received 3
To see the stack trace of this error execute with --v=5 or higher

wurly@k8s3:~$ kubeadm join 192.168.1.201:6443 --token mu8v4r.5e7v4uibqkplwmxx \
    --discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960 
> accepts at most 1 arg(s), received 3
To see the stack trace of this error execute with --v=5 or higher

よくわからないメッセージが表示されてしまいました。テキストのコピペの問題がありそうなので、改行部分を除去して実行しました。

wurly@k8s2:~$ kubeadm join 192.168.1.201:6443 --token mu8v4r.5e7v4uibqkplwmxx --discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960
[preflight] Running pre-flight checks
error execution phase preflight: [preflight] Some fatal errors occurred:
    [ERROR IsPrivilegedUser]: user is not running as root
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher

ルート権限が必要です。sudo を使います。

k8s2 での実行結果は下記の通りです。

wurly@k8s2:~$ sudo kubeadm join 192.168.1.201:6443 --token mu8v4r.5e7v4uibqkplwmxx --discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960
[sudo] password for wurly: 
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

k8s3 での実行結果は下記の通りです。

wurly@k8s3:~$ sudo kubeadm join 192.168.1.201:6443 --token mu8v4r.5e7v4uibqkplwmxx --discovery-token-ca-cert-hash sha256:de9e4adece0fbdcbd04b0e21282b2cb30d8060bbb972777294489891100bf960
[sudo] password for wurly: 
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

クラスタが構成されていることを確認 (マスターノードで実行)

kubectl get nodes にてノードの状態を確認します。直後に get nodes するとワーカーノードが追加されてReadyになる様子が見られました。

wurly@k8s1:~$ kubectl get nodes
NAME   STATUS     ROLES           AGE   VERSION
k8s1   Ready      control-plane   16m   v1.28.2
k8s2   NotReady   <none>          31s   v1.28.2
k8s3   NotReady   <none>          8s    v1.28.2
wurly@k8s1:~$ kubectl get nodes
NAME   STATUS     ROLES           AGE   VERSION
k8s1   Ready      control-plane   16m   v1.28.2
k8s2   Ready      <none>          54s   v1.28.2
k8s3   NotReady   <none>          31s   v1.28.2
wurly@k8s1:~$ kubectl get nodes
NAME   STATUS   ROLES           AGE   VERSION
k8s1   Ready    control-plane   17m   v1.28.2
k8s2   Ready    <none>          72s   v1.28.2
k8s3   Ready    <none>          49s   v1.28.2

また、ワーカーノード側のcalico-nodeが生成される様子も見られます。

wurly@k8s1:~$ kubectl get pods -n kube-system
NAME                                       READY   STATUS     RESTARTS   AGE
calico-kube-controllers-658d97c59c-gjb8r   1/1     Running    0          7m55s
calico-node-2xp2w                          0/1     Init:2/3   0          64s
calico-node-fhglf                          1/1     Running    0          7m55s
calico-node-zdnm7                          0/1     Running    0          87s
coredns-5dd5756b68-2dfmx                   1/1     Running    0          17m
coredns-5dd5756b68-z2pxd                   1/1     Running    0          17m
etcd-k8s1                                  1/1     Running    0          17m
kube-apiserver-k8s1                        1/1     Running    0          17m
kube-controller-manager-k8s1               1/1     Running    0          17m
kube-proxy-6db5z                           1/1     Running    0          64s
kube-proxy-kkv4r                           1/1     Running    0          17m
kube-proxy-llj5q                           1/1     Running    0          87s
kube-scheduler-k8s1                        1/1     Running    0          17m
wurly@k8s1:~$ kubectl get pods -n kube-system
NAME                                       READY   STATUS    RESTARTS   AGE
calico-kube-controllers-658d97c59c-gjb8r   1/1     Running   0          8m30s
calico-node-2xp2w                          1/1     Running   0          99s
calico-node-fhglf                          1/1     Running   0          8m30s
calico-node-zdnm7                          1/1     Running   0          2m2s
coredns-5dd5756b68-2dfmx                   1/1     Running   0          17m
coredns-5dd5756b68-z2pxd                   1/1     Running   0          17m
etcd-k8s1                                  1/1     Running   0          17m
kube-apiserver-k8s1                        1/1     Running   0          17m
kube-controller-manager-k8s1               1/1     Running   0          17m
kube-proxy-6db5z                           1/1     Running   0          99s
kube-proxy-kkv4r                           1/1     Running   0          17m
kube-proxy-llj5q                           1/1     Running   0          2m2s
kube-scheduler-k8s1                        1/1     Running   0          17m

お試しで、kubectl run で nginxイメージでシェルを起動してみます。

wurly@k8s1:~$ kubectl run --image=nginx:1.16 --restart=Never --rm -it sample-debug --command -- /bin/sh

podが立ち上がりました。

wurly@k8s1:~$ kubectl get pod -A
NAMESPACE     NAME                                       READY   STATUS    RESTARTS        AGE
default       sample-debug                               1/1     Running   0               75s
kube-system   calico-kube-controllers-658d97c59c-gjb8r   1/1     Running   1 (3h48m ago)   20h
kube-system   calico-node-2xp2w                          1/1     Running   2 (3h47m ago)   20h
kube-system   calico-node-fhglf                          1/1     Running   1 (3h48m ago)   20h
kube-system   calico-node-zdnm7                          1/1     Running   1 (3h48m ago)   20h
kube-system   coredns-5dd5756b68-2dfmx                   1/1     Running   1 (3h48m ago)   21h
kube-system   coredns-5dd5756b68-z2pxd                   1/1     Running   1 (3h48m ago)   21h
kube-system   etcd-k8s1                                  1/1     Running   1 (3h48m ago)   21h
kube-system   kube-apiserver-k8s1                        1/1     Running   1 (3h48m ago)   21h
kube-system   kube-controller-manager-k8s1               1/1     Running   1 (3h48m ago)   21h
kube-system   kube-proxy-6db5z                           1/1     Running   1 (3h48m ago)   20h
kube-system   kube-proxy-kkv4r                           1/1     Running   1 (3h48m ago)   21h
kube-system   kube-proxy-llj5q                           1/1     Running   1 (3h48m ago)   20h
kube-system   kube-scheduler-k8s1                        1/1     Running   1 (3h48m ago)   21h

これで、Kubernetesクラスターの構築は完了です。

(参考)Kubenetesの理解を深める

行ったこと

最低限の作業で構築されたクラスターについてファイルを参照したり、kubectl を叩くことで学びを得ます。

これらの情報を、Kubernetes完全ガイド第2版 (青山真也著) 19章「Kubenetes のアーキテクチャを知る」を読みながら参照することで非常に理解が深まりました。

https://www.amazon.co.jp/dp/4295009792/

kubeadm init の実行結果

コマンド実行後に出力されたテキストには、内部で実行されたログと、この後に行うべきアクションが含まれます。ログの内容から設定ファイルの場所等が読み取れます。

wurly@k8s1:~$ sudo kubeadm init
I0203 16:34:26.708499   23499 version.go:256] remote version is much newer: v1.29.1; falling back to: stable-1.28
[init] Using Kubernetes version: v1.28.6
[preflight] Running pre-flight checks
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
W0203 16:35:06.461263   23499 checks.go:835] detected that the sandbox image "registry.k8s.io/pause:3.6" of the container runtime is inconsistent with that used by kubeadm. It is recommended that using "registry.k8s.io/pause:3.9" as the CRI sandbox image.
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.1.201]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [k8s1 localhost] and IPs [192.168.1.201 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s1 localhost] and IPs [192.168.1.201 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 19.518434 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node k8s1 as control-plane by adding the labels: [node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node k8s1 as control-plane by adding the taints [node-role.kubernetes.io/control-plane:NoSchedule]
[bootstrap-token] Using token: mu8v4r.5e7v4uibqkplwmxx
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

設定ファイル(マスターノード)

設定ファイルは /etc/kubernetes に作成されます。

wurly@k8s1:~$ ls -la /etc/kubernetes
total 44
drwxr-xr-x  4 root root 4096 Feb  3 16:35 .
drwxr-xr-x 98 root root 4096 Feb  3 16:30 ..
-rw-------  1 root root 5649 Feb  3 16:35 admin.conf
-rw-------  1 root root 5681 Feb  3 16:35 controller-manager.conf
-rw-------  1 root root 1961 Feb  3 16:36 kubelet.conf
drwxr-xr-x  2 root root 4096 Feb  3 16:35 manifests
drwxr-xr-x  3 root root 4096 Feb  3 16:35 pki
-rw-------  1 root root 5629 Feb  3 16:35 scheduler.conf

マニフェストファイル(マスターノード)

wurly@k8s1:~$ ls -la /etc/kubernetes/manifests
total 24
drwxr-xr-x 2 root root 4096 Feb  3 16:35 .
drwxr-xr-x 4 root root 4096 Feb  3 16:35 ..
-rw------- 1 root root 2395 Feb  3 16:35 etcd.yaml
-rw------- 1 root root 3887 Feb  3 16:35 kube-apiserver.yaml
-rw------- 1 root root 3279 Feb  3 16:35 kube-controller-manager.yaml
-rw------- 1 root root 1463 Feb  3 16:35 kube-scheduler.yaml

ルートCAを含む各種証明書、鍵(マスターノード)

wurly@k8s1:~$ ls -la /etc/kubernetes/pki
total 68
drwxr-xr-x 3 root root 4096 Feb  3 16:35 .
drwxr-xr-x 4 root root 4096 Feb  3 16:35 ..
-rw-r--r-- 1 root root 1155 Feb  3 16:35 apiserver-etcd-client.crt
-rw------- 1 root root 1679 Feb  3 16:35 apiserver-etcd-client.key
-rw-r--r-- 1 root root 1164 Feb  3 16:35 apiserver-kubelet-client.crt
-rw------- 1 root root 1679 Feb  3 16:35 apiserver-kubelet-client.key
-rw-r--r-- 1 root root 1277 Feb  3 16:35 apiserver.crt
-rw------- 1 root root 1679 Feb  3 16:35 apiserver.key
-rw-r--r-- 1 root root 1107 Feb  3 16:35 ca.crt
-rw------- 1 root root 1675 Feb  3 16:35 ca.key
drwxr-xr-x 2 root root 4096 Feb  3 16:35 etcd
-rw-r--r-- 1 root root 1123 Feb  3 16:35 front-proxy-ca.crt
-rw------- 1 root root 1675 Feb  3 16:35 front-proxy-ca.key
-rw-r--r-- 1 root root 1119 Feb  3 16:35 front-proxy-client.crt
-rw------- 1 root root 1675 Feb  3 16:35 front-proxy-client.key
-rw------- 1 root root 1675 Feb  3 16:35 sa.key
-rw------- 1 root root  451 Feb  3 16:35 sa.pub

admin.conf(マスターノード)

wurly@k8s1:~$ sudo cat /etc/kubernetes/admin.conf
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: LS0tL...LS0K
    server: https://192.168.1.201:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: kubernetes-admin
  name: kubernetes-admin@kubernetes
current-context: kubernetes-admin@kubernetes
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: LS0tL...LS0tCg==
    client-key-data: LS0tL...LQo=

設定ファイル(ワーカーノード)

設定ファイルは /etc/kubernetes に作成されます。

wurly@k8s2:~$ ls -la /etc/kubernetes/
total 20
drwxr-xr-x  4 root root 4096 Feb  3 16:52 .
drwxr-xr-x 98 root root 4096 Feb  3 16:30 ..
-rw-------  1 root root 1962 Feb  3 16:51 kubelet.conf
drwxr-xr-x  2 root root 4096 Jan 28 21:36 manifests
drwxr-xr-x  2 root root 4096 Feb  3 16:51 pki

マニフェストファイル(ワーカーノード)

wurly@k8s2:~$ ls -la /etc/kubernetes/manifests
total 8
drwxr-xr-x 2 root root 4096 Jan 28 21:36 .
drwxr-xr-x 4 root root 4096 Feb  3 16:52 ..

ルートCAを含む各種証明書、鍵(ワーカーノード)

wurly@k8s2:~$ ls -la /etc/kubernetes/pki
total 12
drwxr-xr-x 2 root root 4096 Feb  3 16:51 .
drwxr-xr-x 4 root root 4096 Feb  3 16:52 ..
-rw-r--r-- 1 root root 1107 Feb  3 16:51 ca.crt

namespace、podの状態など

wurly@k8s1:~$ kubectl get namespace
NAME              STATUS   AGE
default           Active   19h
kube-node-lease   Active   19h
kube-public       Active   19h
kube-system       Active   19h

wurly@k8s1:~$ kubectl get pod -A
NAMESPACE     NAME                                       READY   STATUS    RESTARTS       AGE
kube-system   calico-kube-controllers-658d97c59c-gjb8r   1/1     Running   1 (128m ago)   19h
kube-system   calico-node-2xp2w                          1/1     Running   2 (127m ago)   19h
kube-system   calico-node-fhglf                          1/1     Running   1 (128m ago)   19h
kube-system   calico-node-zdnm7                          1/1     Running   1 (128m ago)   19h
kube-system   coredns-5dd5756b68-2dfmx                   1/1     Running   1 (128m ago)   19h
kube-system   coredns-5dd5756b68-z2pxd                   1/1     Running   1 (128m ago)   19h
kube-system   etcd-k8s1                                  1/1     Running   1 (128m ago)   19h
kube-system   kube-apiserver-k8s1                        1/1     Running   1 (128m ago)   19h
kube-system   kube-controller-manager-k8s1               1/1     Running   1 (128m ago)   19h
kube-system   kube-proxy-6db5z                           1/1     Running   1 (128m ago)   19h
kube-system   kube-proxy-kkv4r                           1/1     Running   1 (128m ago)   19h
kube-system   kube-proxy-llj5q                           1/1     Running   1 (128m ago)   19h
kube-system   kube-scheduler-k8s1                        1/1     Running   1 (128m ago)   19h

wurly@k8s1:~$ kubectl get ConfigMap -A
NAMESPACE         NAME                                                   DATA   AGE
default           kube-root-ca.crt                                       1      19h
kube-node-lease   kube-root-ca.crt                                       1      19h
kube-public       cluster-info                                           2      19h
kube-public       kube-root-ca.crt                                       1      19h
kube-system       calico-config                                          4      19h
kube-system       coredns                                                1      19h
kube-system       extension-apiserver-authentication                     6      19h
kube-system       kube-apiserver-legacy-service-account-token-tracking   1      19h
kube-system       kube-proxy                                             2      19h
kube-system       kube-root-ca.crt                                       1      19h
kube-system       kubeadm-config                                         1      19h
kube-system       kubelet-config                                         1      19h

参考にしたサイト

おわりに

私の「おうちKubernetes」の目的は、まずは技術のキャッチアップであったので、逐次、作業の内容の意味を調べて確認し、その内容を記載しながら、進めました。

このように作業したおかげで特に途中で躓くことはありませんでした。

ほぼ週末しか作業できなかったので数週間かかりましたが、kubeadmを使った構築は実際のところ作業は平易でした。

一方で、自分で手を動かしてやってみることで思っていた以上にかなりKubernetesに対する理解が深まりました。

普段Kubernetesを使用しているが、実際のマシンを使って構築を行ったことが無い方には、おすすめできる内容です。(それなりにお金はかかりますが・・・)

この後、この環境を使ってデプロイなどを試していきます。