Cluster Overview ¶

Contents ¶

Container Layer
Kubernetes Layer

Information:

For environment setup, refer to Installation on Aliyun Ubuntu

Container Layer ¶

Scenario: Use Containerd service to manage our images and containers via command nerdctl, which is same concept with Docker.

Get namespace.
Get containers.
Get images.
Get volumes.
Get overall status.
Get network status.

Demo:

Get namespaces.

sudo nerdctl namespace ls

Result

NAME      CONTAINERS    IMAGES    VOLUMES    LABELS
k8s.io    21            30        0

Get containers under specific namespace k8s.io.

sudo nerdctl -n k8s.io ps

Result

CONTAINER ID    IMAGE                                                                      COMMAND                   CREATED         STATUS    PORTS    NAMES
0a3625f22f65    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/coredns-74586cf9b6-4jwmk
121af2ecd1a1    registry.aliyuncs.com/google_containers/coredns:v1.8.6                     "/coredns -conf /etc…"    16 hours ago    Up                 k8s://kube-system/coredns-74586cf9b6-c5mll/coredns
49f6c7e3efe5    registry.aliyuncs.com/google_containers/kube-proxy:v1.24.0                 "/usr/local/bin/kube…"    16 hours ago    Up                 k8s://kube-system/kube-proxy-dmj2t/kube-proxy
4bba5fbd701d    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/kube-scheduler-cka001
57d47b57eb12    docker.io/calico/node:v3.23.3                                              "start_runit"             16 hours ago    Up                 k8s://kube-system/calico-node-w8nvl/calico-node
5ce4c351a886    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/calico-node-w8nvl
6456eef784bf    registry.aliyuncs.com/google_containers/kube-scheduler:v1.24.0             "kube-scheduler --au…"    16 hours ago    Up                 k8s://kube-system/kube-scheduler-cka001/kube-scheduler
6a687305871c    registry.aliyuncs.com/google_containers/kube-apiserver:v1.24.0             "kube-apiserver --ad…"    16 hours ago    Up                 k8s://kube-system/kube-apiserver-cka001/kube-apiserver
7dcb24568574    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/coredns-74586cf9b6-c5mll
a06b101118b8    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/kube-controller-manager-cka001
a07ef8c3fc3a    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/etcd-cka001
b8566d3e4174    registry.aliyuncs.com/google_containers/kube-controller-manager:v1.24.0    "kube-controller-man…"    16 hours ago    Up                 k8s://kube-system/kube-controller-manager-cka001/kube-controller-manager
ca6ac26314ff    registry.aliyuncs.com/google_containers/coredns:v1.8.6                     "/coredns -conf /etc…"    16 hours ago    Up                 k8s://kube-system/coredns-74586cf9b6-4jwmk/coredns
cdc041b4791e    registry.aliyuncs.com/google_containers/etcd:3.5.3-0                       "etcd --advertise-cl…"    16 hours ago    Up                 k8s://kube-system/etcd-cka001/etcd
e0c59abadf2e    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/kube-proxy-dmj2t
e0d2e5f6ccff    registry.aliyuncs.com/google_containers/pause:3.6                          "/pause"                  16 hours ago    Up                 k8s://kube-system/kube-apiserver-cka001

Get images.

sudo nerdctl -n k8s.io image ls -a

Get volumes. After inintial installation, no volume within namespaces.

sudo nerdctl -n k8s.io volume ls

Get overall status

sudo nerdctl stats

Get network status.

sudo nerdctl network ls
sudo nerdctl network inspect bridge
sudo nerdctl network inspect k8s-pod-network

Result

NETWORK ID    NAME               FILE
              k8s-pod-network    /etc/cni/net.d/10-calico.conflist
0             bridge             /etc/cni/net.d/nerdctl-bridge.conflist
              host               
              none

Get network interface in host cka001 with command ip addr list.

IP pool of 10.4.0.1/24 is ipam and defined in /etc/cni/net.d/nerdctl-bridge.conflist.

lo                   : inet 127.0.0.1/8 qlen 1000
eth0                 : inet <cka001_ip>/24 brd xxx.xxx.xxx.255 scope global dynamic eth0
tunl0@NONE           : inet 10.244.228.192/32 scope global tunl0
cali96e32d88db2@if4  :
cali93613212490@if4  :

Kubernetes Layer ¶

Scenario:

Nodes
Namespaces
System Pods

Demo:

Information:

In the demo, there are three nodes, cka001, cka002, and cka003.

Get nodes status.

kubectl get node -o wide

There are four initial namespaces across three nodes.

kubectl get namespace -A

Result

NAME              STATUS   AGE
default           Active   56m
kube-node-lease   Active   56m
kube-public       Active   56m
kube-system       Active   56m

There are some initial pods.

kubectl get pod -A -o wide

Result

NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE   NODE     NOMINATED NODE   READINESS GATES
kube-system   calico-kube-controllers-555bc4b957-l8bn2   1/1     Running   0          15h   cka003   <none>           <none>
kube-system   calico-node-255pc                          1/1     Running   0          15h   cka003   <none>           <none>
kube-system   calico-node-7tmnb                          1/1     Running   0          15h   cka002   <none>           <none>
kube-system   calico-node-w8nvl                          1/1     Running   0          15h   cka001   <none>           <none>
kube-system   coredns-74586cf9b6-4jwmk                   1/1     Running   0          15h   cka001   <none>           <none>
kube-system   coredns-74586cf9b6-c5mll                   1/1     Running   0          15h   cka001   <none>           <none>
kube-system   etcd-cka001                                1/1     Running   0          15h   cka001   <none>           <none>
kube-system   kube-apiserver-cka001                      1/1     Running   0          15h   cka001   <none>           <none>
kube-system   kube-controller-manager-cka001             1/1     Running   0          15h   cka001   <none>           <none>
kube-system   kube-proxy-dmj2t                           1/1     Running   0          15h   cka001   <none>           <none>
kube-system   kube-proxy-n77zw                           1/1     Running   0          15h   cka002   <none>           <none>
kube-system   kube-proxy-qs6rf                           1/1     Running   0          15h   cka003   <none>           <none>
kube-system   kube-scheduler-cka001                      1/1     Running   0          15h   cka001   <none>           <none>

Summary:

Below shows the relationship between containers and pods.

Master node:
CoreDNS: 2 Pod
etcd: 1 Pod
apiserver: 1 Pod
controller-manager: 1 Pod
scheduler: 1 Pod
Calico Controller: 1 Pod
All nodes:
Calico Node: 1 Pod each
Proxy: 1 Pod each

Reference

Container pause: article and artical.
nerdctl