このリポジトリをクローンして、01-docker-and-k8s のディレクトリに移動しておきます。
$ git clone https://github.com/inductor/docker-to-k8s.git
$ cd docker-to-k8s/01-docker-and-k8sDocker Compose の YAML から Kubernetes の YAML を生成するには Kompose を使います。まずは公式ドキュメントに沿ってインストールしてみましょう。
# Linux
$ curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-linux-amd64 -o kompose
# macOS
$ curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-darwin-amd64 -o kompose
$ chmod +x kompose
$ sudo mv ./kompose /usr/local/bin/kompose導入できたら早速実行してみることにします。
$ kompose convert -f docker-compose.yaml -o k8s/ --with-kompose-annotation=false
WARN Volume mount on the host "/home/kela/ghq/src/github.com/inductor/docker-to-k8s/01-docker-and-k8s/data" isn't supported - ignoring path on the host
WARN Volume mount on the host "/home/kela/ghq/src/github.com/inductor/docker-to-k8s/01-docker-and-k8s/conf.d" isn't supported - ignoring path on the host
INFO Kubernetes file "k8s/minecraft-service.yaml" created
INFO Kubernetes file "k8s/nginx-service.yaml" created
INFO Kubernetes file "k8s/minecraft-deployment.yaml" created
INFO Kubernetes file "k8s/minecraft-claim0-persistentvolumeclaim.yaml" created
INFO Kubernetes file "k8s/nginx-deployment.yaml" created
INFO Kubernetes file "k8s/nginx-claim0-persistentvolumeclaim.yaml" createdなんか YAML が生成されましたね。では次に Kubernetes 環境を用意します
kind を使うと、Kubernetes を Docker 上に建てることができます。名前の通り "kind (Kubernetes-in-Docker)" になっていますね。
$ curl -L https://github.com/kubernetes-sigs/kind/releases/download/v0.11.1/kind-linux-amd64 -o kind
$ chmod +x kind
$ sudo mv ./kind /usr/local/bin/kind導入できたらクラスターを作ります。
$ kind create cluster
Creating cluster "kind" ...
✓ Ensuring node image (kindest/node:v1.21.1) 🖼
✓ Preparing nodes 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
Set kubectl context to "kind-kind"
You can now use your cluster with:
kubectl cluster-info --context kind-kind
Have a nice day! 👋環境ができたので k8s ディレクトリ配下に作られた YAML をとりあえず全部突っ込んでみます。
$ kubectl apply -f k8s/
persistentvolumeclaim/minecraft-claim0 created
deployment.apps/minecraft created
service/minecraft created
persistentvolumeclaim/nginx-claim0 created
deployment.apps/nginx created
service/nginx created
できちゃった！！便利。
$ kubectl get pod
NAME READY STATUS RESTARTS AGE
minecraft-6cf746949f-d7g76 1/1 Running 0 116s
nginx-67885c6774-hvfjs 1/1 Running 0 116s
$ kubectl logs minecraft-6cf746949f-d7g76
[init] Changing ownership of /data to 1000 ...
[init] Running as uid=1000 gid=1000 with /data as 'drwxrwxrwx 2 1000 1000 4096 Dec 22 18:06 /data'
[init] Resolved version given 1.18.1 into 1.18.1
[init] Resolving type given SPIGOT
[init] Downloading Spigot from https://download.getbukkit.org/spigot/spigot-1.18.1.jar ...
[init] Downloading mod/plugin https://github.com/webbukkit/dynmap/releases/download/v3.3-beta-2/Dynmap-3.3-beta-2-spigot.jar ...
...コンテナの起動ログも無事見えてますね。以下のように Service を見に行くと ClusterIP で公開されています。
$ kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3m23s
minecraft ClusterIP 10.96.23.45 <none> 25565/TCP,8123/TCP 2m46s
nginx ClusterIP 10.96.242.201 <none> 80/TCP,443/TCP 2m46s次にコンテナの中に入ってマウントされているはずの conf を見てみましょう
$ kubectl exec -it nginx-67885c6774-hvfjs -- cat /etc/nginx/conf.d/default.conf
cat: /etc/nginx/conf.d/default.conf: No such file or directoryえ、ないじゃん・・・。なんで？
無いのが普通です。Kubernetes ではコンテナに外部情報を注入するときは Volume を直接使うのではなく ConfigMap というものを使います。
$ kubectl create configmap nginx-config --from-file=conf.d/default.confConfigMap は生成するとこんな感じになります。
$ kubectl describe configmap nginx-config
Name: nginx-config
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
default.conf:
----
server {
listen 80;
server_name localhost;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_read_timeout 6;
# That is my dynmap webserver which is only accessible via localhost or through nginx
proxy_pass http://minecraft:8123;
break;
}
}
BinaryData
====
Events: <none>
これを nginx から読み込むためには以下のような変更を YAML に加えます。
$ diff k8s/nginx-deployment.yaml k8s-patch/nginx-deployment-configmap.yaml
--- nginx-deployment.yaml 2021-12-23 13:20:22.035535873 +0900
+++ nginx-deployment-configmap.yaml 2021-12-23 13:21:46.935535979 +0900
@@ -29,10 +29,10 @@
tty: true
volumeMounts:
- mountPath: /etc/nginx/conf.d
- name: nginx-claim0
- restartPolicy: Always
+ name: nginx-config-volume
volumes:
- - name: nginx-claim0
- persistentVolumeClaim:
- claimName: nginx-claim0
+ - name: nginx-config-volume
+ configMap:
+ name: nginx-config
+ restartPolicy: Always
status: {}Kubernetes 上に変更を適用する前に、実際の差分を計算するコマンドもあります。
$ kubectl diff -f k8s-patch/nginx-deployment-configmap.yaml
diff -u -N /tmp/LIVE-641766570/apps.v1.Deployment.default.nginx /tmp/MERGED-2103706877/apps.v1.Deployment.default.nginx
--- /tmp/LIVE-641766570/apps.v1.Deployment.default.nginx 2021-12-23 13:22:03.915536000 +0900
+++ /tmp/MERGED-2103706877/apps.v1.Deployment.default.nginx 2021-12-23 13:22:03.915536000 +0900
@@ -6,7 +6,7 @@
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"creationTimestamp":null,"labels":{"io.kompose.service":"nginx"},"name":"nginx","namespace":"default"},"spec":{"replicas":1,"selector":{"matchLabels":{"io.kompose.service":"nginx"}},"strategy":{"type":"Recreate"},"template":{"metadata":{"creationTimestamp":null,"labels":{"io.kompose.service":"nginx"}},"spec":{"containers":[{"image":"nginx:mainline","name":"nginx","ports":[{"containerPort":80},{"containerPort":443}],"resources":{},"stdin":true,"tty":true,"volumeMounts":[{"mountPath":"/etc/nginx/conf.d","name":"nginx-claim0"}]}],"restartPolicy":"Always","volumes":[{"name":"nginx-claim0","persistentVolumeClaim":{"claimName":"nginx-claim0"}}]}}},"status":{}}
creationTimestamp: "2021-12-22T18:06:34Z"
- generation: 1
+ generation: 2
labels:
io.kompose.service: nginx
managedFields:
@@ -15,6 +15,39 @@
fieldsV1:
f:metadata:
f:annotations:
+ f:deployment.kubernetes.io/revision: {}
+ f:status:
+ f:availableReplicas: {}
+ f:conditions:
+ .: {}
+ k:{"type":"Available"}:
+ .: {}
+ f:lastTransitionTime: {}
+ f:lastUpdateTime: {}
+ f:message: {}
+ f:reason: {}
+ f:status: {}
+ f:type: {}
+ k:{"type":"Progressing"}:
+ .: {}
+ f:lastTransitionTime: {}
+ f:lastUpdateTime: {}
+ f:message: {}
+ f:reason: {}
+ f:status: {}
+ f:type: {}
+ f:observedGeneration: {}
+ f:readyReplicas: {}
+ f:replicas: {}
+ f:updatedReplicas: {}
+ manager: kube-controller-manager
+ operation: Update
+ time: "2021-12-22T18:06:48Z"
+ - apiVersion: apps/v1
+ fieldsType: FieldsV1
+ fieldsV1:
+ f:metadata:
+ f:annotations:
.: {}
f:kubectl.kubernetes.io/last-applied-configuration: {}
f:labels:
@@ -67,48 +100,16 @@
f:terminationGracePeriodSeconds: {}
f:volumes:
.: {}
- k:{"name":"nginx-claim0"}:
+ k:{"name":"nginx-config-volume"}:
.: {}
- f:name: {}
- f:persistentVolumeClaim:
+ f:configMap:
.: {}
- f:claimName: {}
+ f:defaultMode: {}
+ f:name: {}
+ f:name: {}
manager: kubectl-client-side-apply
operation: Update
- time: "2021-12-22T18:06:34Z"
- - apiVersion: apps/v1
- fieldsType: FieldsV1
- fieldsV1:
- f:metadata:
- f:annotations:
- f:deployment.kubernetes.io/revision: {}
- f:status:
- f:availableReplicas: {}
- f:conditions:
- .: {}
- k:{"type":"Available"}:
- .: {}
- f:lastTransitionTime: {}
- f:lastUpdateTime: {}
- f:message: {}
- f:reason: {}
- f:status: {}
- f:type: {}
- k:{"type":"Progressing"}:
- .: {}
- f:lastTransitionTime: {}
- f:lastUpdateTime: {}
- f:message: {}
- f:reason: {}
- f:status: {}
- f:type: {}
- f:observedGeneration: {}
- f:readyReplicas: {}
- f:replicas: {}
- f:updatedReplicas: {}
- manager: kube-controller-manager
- operation: Update
- time: "2021-12-22T18:06:48Z"
+ time: "2021-12-23T04:22:03Z"
name: nginx
namespace: default
resourceVersion: "681"
@@ -144,16 +145,17 @@
tty: true
volumeMounts:
- mountPath: /etc/nginx/conf.d
- name: nginx-claim0
+ name: nginx-config-volume
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
volumes:
- - name: nginx-claim0
- persistentVolumeClaim:
- claimName: nginx-claim0
+ - configMap:
+ defaultMode: 420
+ name: nginx-config
+ name: nginx-config-volume
status:
availableReplicas: 1
conditions:よくわかりませんがそれっぽい差分がでましたね。Apply しちゃいましょう。
$ kubectl apply -f k8s-patch/nginx-deployment-configmap.yaml
deployment.apps/nginx configured更新の様子を見てみましょう
$ kubectl get pod -n default
NAME READY STATUS RESTARTS AGE
minecraft-6cf746949f-g77xm 1/1 Running 0 2m45s
nginx-594cb68ff7-svtf6 1/1 Running 0 4s
無事に Pod が入れ替わりました！！！！！やったね！！！
コンテナの中に config も無事に入ってそう。
$ kubectl exec -it nginx-594cb68ff7-svtf6 -- ls /etc/nginx/conf.d
default.confkubectl port-forward してブラウザ上で http://localhost:8080 にアクセスすると、無事 dynmap が見えました。
$ kubectl port-forward deployments/nginx 8080:80
終わったら Ctrl + C かなんかで終われば良い。
$ kind delete clusterでさようなら