<p>I read the calico docs, it says calico will start an etcd instance when it starts, but I noticed that the K8s cluster will start an etcd pod, when the cluster starts. I want calico use that etcd node, so I do the following action:</p>

<p>Use calicoctl do test, create a config file:</p>

<pre><code># cat myconfig.yml
apiVersion: projectcalico.org/v3
kind: CalicoAPIConfig
metadata:
spec:
  datastoreType: etcdv3
  etcdEndpoints: https://10.100.1.20:2379
  etcdKeyFile: /etc/kubernetes/pki/etcd/server.key
  etcdCertFile: /etc/kubernetes/pki/etcd/server.crt
  etcdCACertFile: /etc/kubernetes/pki/etcd/ca.crt
</code></pre>

<p>the etcd config info came from /etc/kubernetes/manifests/etcd.yaml</p>

<pre><code># cat /etc/kubernetes/manifests/etcd.yaml
apiVersion: v1
kind: Pod
metadata:
  annotations:
    scheduler.alpha.kubernetes.io/critical-pod: ""
  creationTimestamp: null
  labels:
    component: etcd
    tier: control-plane
  name: etcd
  namespace: kube-system
spec:
  containers:
  - command:
    - etcd
    - --advertise-client-urls=https://127.0.0.1:2379
    - --cert-file=/etc/kubernetes/pki/etcd/server.crt
    - --client-cert-auth=true
    - --data-dir=/var/lib/etcd
    - --initial-advertise-peer-urls=https://127.0.0.1:2380
    - --initial-cluster=t-k8s-a1=https://127.0.0.1:2380
    - --key-file=/etc/kubernetes/pki/etcd/server.key
    - --listen-client-urls=https://127.0.0.1:2379
    - --listen-peer-urls=https://127.0.0.1:2380
    - --name=t-k8s-a1
    - --peer-cert-file=/etc/kubernetes/pki/etcd/peer.crt
    - --peer-client-cert-auth=true
    - --peer-key-file=/etc/kubernetes/pki/etcd/peer.key
    - --peer-trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    - --snapshot-count=10000
    - --trusted-ca-file=/etc/kubernetes/pki/etcd/ca.crt
    image: k8s.gcr.io/etcd-amd64:3.2.18
    imagePullPolicy: IfNotPresent
    livenessProbe:
      exec:
        command:
        - /bin/sh
        - -ec
        - ETCDCTL_API=3 etcdctl --endpoints=https://[127.0.0.1]:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt
          --cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt --key=/etc/kubernetes/pki/etcd/healthcheck-client.key
          get foo
      failureThreshold: 8
      initialDelaySeconds: 15
      timeoutSeconds: 15
    name: etcd
    resources: {}
    volumeMounts:
    - mountPath: /var/lib/etcd
      name: etcd-data
    - mountPath: /etc/kubernetes/pki/etcd
      name: etcd-certs
  hostNetwork: true
  priorityClassName: system-cluster-critical
  volumes:
  - hostPath:
      path: /var/lib/etcd
      type: DirectoryOrCreate
    name: etcd-data
  - hostPath:
      path: /etc/kubernetes/pki/etcd
      type: DirectoryOrCreate
    name: etcd-certs
status: {}
</code></pre>

<p>still refused  </p>

<pre><code># calicoctl get nodes --config ./myconfig.yml
Failed to create Calico API client: dial tcp 10.100.1.20:2379: connect: connection refused


# kubectl get pods --all-namespaces -o wide
NAMESPACE     NAME                                READY     STATUS    RESTARTS   AGE       IP             NODE       NOMINATED NODE
kube-system   calico-node-5nbwz                   2/2       Running   0          22h       10.100.1.21    t-k8s-b2   &lt;none&gt;
kube-system   calico-node-m967m                   2/2       Running   0          22h       10.100.1.20    t-k8s-a1   &lt;none&gt;
kube-system   calico-typha-64fc9d86dd-g8m54       1/1       Running   0          22h       10.100.1.21    t-k8s-b2   &lt;none&gt;
kube-system   coredns-78fcdf6894-5thqv            1/1       Running   0          1d        192.168.1.2    t-k8s-b2   &lt;none&gt;
kube-system   coredns-78fcdf6894-gm5zs            1/1       Running   0          1d        192.168.1.3    t-k8s-b2   &lt;none&gt;
kube-system   etcd-t-k8s-a1                       1/1       Running   0          1d        10.100.1.20    t-k8s-a1   &lt;none&gt;
kube-system   kube-apiserver-t-k8s-a1             1/1       Running   0          1d        10.100.1.20    t-k8s-a1   &lt;none&gt;
kube-system   kube-controller-manager-t-k8s-a1    1/1       Running   0          1d        10.100.1.20    t-k8s-a1   &lt;none&gt;
kube-system   kube-proxy-9rgmd                    1/1       Running   0          1d        10.100.1.20    t-k8s-a1   &lt;none&gt;
kube-system   kube-proxy-z75kc                    1/1       Running   0          1d        10.100.1.21    t-k8s-b2   &lt;none&gt;
kube-system   kube-scheduler-t-k8s-a1             1/1       Running   0          1d        10.100.1.20    t-k8s-a1   &lt;none&gt;
testalex      etcd-deployment-5b5d67bb84-nr7vc    1/1       Running   0          1d        192.168.1.26   t-k8s-b2   &lt;none&gt;
testalex      k8s-alert-76f97ccf49-gffgb          1/1       Running   0          1d        192.168.1.18   t-k8s-b2   &lt;none&gt;
testalex      k8s-monitor-7ddcb74b87-75vxb        1/1       Running   0          1d        192.168.1.27   t-k8s-b2   &lt;none&gt;
testalex      mysql-deployment-858464457f-nznq5   1/1       Running   0          1d        192.168.1.16   t-k8s-b2   &lt;none&gt;
</code></pre>

<p>When you <a href="https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/calico" rel="noreferrer">install Calico on Kubernetes</a> by default it will use the Kubernetes datastore (which uses etcdv3). Your <code>calicoctl</code> config under <code>/etc/calico/calicoctl.cfg</code> should looks something like this:</p>

<pre><code>apiVersion: projectcalico.org/v3
kind: CalicoAPIConfig
metadata:
spec:
  datastoreType: "kubernetes"
  kubeconfig: "/path/to/.kube/config"
</code></pre>

<p>It works for me:</p>

<pre><code>calicoctl get nodes
NAME
ip-172-x-x-x.us-west-2.compute.internal
ip-172-x-x-x.us-west-2.compute.internal
ip-172-x-x-x.us-west-2.compute.internal
ip-172-x-x-x.us-west-2.compute.internal
ip-172-x-x-x.us-west-2.compute.internal
ip-172-x-x-x.us-west-2.compute.internal
</code></pre>
