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bootstrapping etcd

coreosがetcd docker image を提供 していますが、Raspberry Piに搭載されているARM CPUのアーキテクチャ armv8(64bit) で利用可能なimageは提供していないため、imageをbuildします。

手順

  1. Dockerfile_etcd.armhf を作成する

    Dockerfile_etcd.armhf 
    cat << 'EOF' > Dockerfile_etcd.armhf
FROM arm64v8/ubuntu:bionic AS etcd-builder

RUN set -ex \
  && apt update \
  && apt install -y git tar zip curl \
  && apt clean

RUN set -ex \
  && curl -L https://go.dev/dl/go1.22.3.linux-arm64.tar.gz | tar -zxC /usr/local

RUN set -ex \
  && git clone https://github.com/etcd-io/etcd.git -b v3.5.13 /tmp/etcd\
  && cd /tmp/etcd \
  && PATH=$PATH:/usr/local/go/bin:~/go/bin ./build



FROM arm64v8/ubuntu:bionic

COPY --from=etcd-builder /tmp/etcd/bin/etcd /usr/local/bin/
COPY --from=etcd-builder /tmp/etcd/bin/etcdctl /usr/local/bin/

RUN set -ex \
  && apt update \
  && apt clean \
  && install -o root -g root -m 700 -d /var/lib/etcd \
  && install -o root -g root -m 644 -d /etc/etcd

COPY ca.pem /etc/etcd/
COPY kubernetes-key.pem /etc/etcd/
COPY kubernetes.pem /etc/etcd/

ENV ETCD_UNSUPPORTED_ARCH=arm64

EXPOSE 2379 2380

ENTRYPOINT ["/usr/local/bin/etcd"]
EOF

  2. image build 

    sudo mkdir -p /etcd-data
sudo nerdctl build --namespace k8s.io -t k8s-etcd --file=Dockerfile_etcd.armhf ./

  3. pod manifestsを /etc/kubelet.d へ作成する

    /etc/kubelet.d/etcd.yaml 
    cat << EOF | sudo tee /etc/kubelet.d/etcd.yaml
---
apiVersion: v1
kind: Pod
metadata:
  annotations:
    kubeadm.kubernetes.io/etcd.advertise-client-urls: https://k8s-master:2379
  name: etcd
  namespace: kube-system
  labels:
    tier: control-plane
    component: etcd

spec:
  # https://kubernetes.io/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/
  priorityClassName: system-node-critical
  hostNetwork: true
  volumes:
  - name: etcd-data-volume
    hostPath:
      path: /etcd-data
      type: Directory
  containers:
    - name: etcd
      image: k8s-etcd:latest
      imagePullPolicy: IfNotPresent
      volumeMounts:
      - mountPath: /etcd-data
        name: etcd-data-volume
      env:
      - name: ETCD_UNSUPPORTED_ARCH
        value: "arm64"
      resources:
        requests:
          cpu: 0.5
          memory: "384Mi"
        limits:
          cpu: 1
          memory: "384Mi"
      command:
        - /usr/local/bin/etcd
        - --data-dir=/etcd-data
        - --advertise-client-urls=https://k8s-master:2379,https://k8s-master:2380
        - --listen-client-urls=https://0.0.0.0:2379
        - --initial-advertise-peer-urls=https://k8s-master:2380
        - --listen-peer-urls=https://0.0.0.0:2380
        - --name=etcd0
        - --cert-file=/etc/etcd/kubernetes.pem
        - --key-file=/etc/etcd/kubernetes-key.pem
        - --peer-cert-file=/etc/etcd/kubernetes.pem
        - --peer-key-file=/etc/etcd/kubernetes-key.pem
        - --trusted-ca-file=/etc/etcd/ca.pem
        - --peer-trusted-ca-file=/etc/etcd/ca.pem
        - --peer-client-cert-auth
        - --client-cert-auth
        - --initial-cluster-token=etcd-cluster-1
        - --initial-cluster=etcd0=https://k8s-master:2380
        - --initial-cluster-state=new
EOF

  4. crictl でコンテナ起動を確認する 

    $ sudo crictl ps --name etcd
CONTAINER           IMAGE                                                              CREATED             STATE               NAME                ATTEMPT             POD ID
72f58248ec087       6e8b8110dc13cfe61d75f867a22c39766a397989413570500f51dedf94be7a12   25 seconds ago       Running             etcd                0                   206c5b952097a

参考文献