問題
kubectl（CentOS 7 上為 1.8.3）錯誤訊息的實際意義以及如何解決。任何了解正在發生的事情的參考資料。我想 kubelet 嘗試與 docker 對話，但不知何故它沒有發生，並且想知道哪些配置是相關的，什麼是，從 Linux 的角度也需要理解哪些概念/機制。
11 月 19 日 22:32:24 master kubelet[4425]: E1119 22:32:24.269786 4425 Summary.go:92] 無法取得「/system.slice/kubelet.service」的系統容器統計資料
：無法取得「/ system.slice/kubelet.service」的cgroup 統計資料「/system.slice/kubelet.service」：無法取得 con
Nov 19 22:32:24 master kubelet[4425]：E1119 22:32:24.269802 4425 Summary.go: 92] 無法取得「/」的系統容器統計資料system.slice/docker.service」：無法取得「/system.slice/docker.service」的 cgroup 統計資料：無法取得 conta
研究
發現了相同的錯誤，並透過更新 kubelet 的服務單元來解決此問題，如下所示，但沒有成功。
/etc/systemd/system/kubelet.service
[Unit]
Description=kubelet: The Kubernetes Node Agent
Documentation=http://kubernetes.io/docs/
[Service]
ExecStart=/usr/bin/kubelet --runtime-cgroups=/systemd/system.slice --kubelet-cgroups=/systemd/system.slice
Restart=always
StartLimitInterval=0
RestartSec=10
[Install]
WantedBy=multi-user.target
背景
透過以下方式設定 Kubernetes 集群安裝 kubeadm。文件中的部分安裝 Docker關於對齊 cgroup 驅動程式的說明如下。
注意：請確保 kubelet 使用的 cgroup 驅動程式與 Docker 使用的 cgroup 驅動程式相同。為了確保相容性，您可以更新 Docker，如下所示：
cat << EOF > /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
EOF
但這樣做會導致docker服務無法啟動：
無法使用檔案 /etc/docker/daemon.json 設定 Docker 守護程式：以下指令都被指定為標誌」。11
月 19 日 16:55:56 localhost.localdomain systemd1：docker.service：主程序已退出，代碼=已退出，狀態=1/FAILURE。
Maser 節點已準備就緒，所有系統 Pod 都在運作。
$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-master 1/1 Running 0 39m
kube-system kube-apiserver-master 1/1 Running 0 39m
kube-system kube-controller-manager-master 1/1 Running 0 39m
kube-system kube-dns-545bc4bfd4-mqqqk 3/3 Running 0 40m
kube-system kube-flannel-ds-fclcs 1/1 Running 2 13m
kube-system kube-flannel-ds-hqlnb 1/1 Running 0 39m
kube-system kube-proxy-t7z5w 1/1 Running 0 40m
kube-system kube-proxy-xdw42 1/1 Running 0 13m
kube-system kube-scheduler-master 1/1 Running 0 39m
環境
CentOS 上的 Kubernetes 1.8.3 和 Flannel。
$ kubectl version -o json | python -m json.tool
{
"clientVersion": {
"buildDate": "2017-11-08T18:39:33Z",
"compiler": "gc",
"gitCommit": "f0efb3cb883751c5ffdbe6d515f3cb4fbe7b7acd",
"gitTreeState": "clean",
"gitVersion": "v1.8.3",
"goVersion": "go1.8.3",
"major": "1",
"minor": "8",
"platform": "linux/amd64"
},
"serverVersion": {
"buildDate": "2017-11-08T18:27:48Z",
"compiler": "gc",
"gitCommit": "f0efb3cb883751c5ffdbe6d515f3cb4fbe7b7acd",
"gitTreeState": "clean",
"gitVersion": "v1.8.3",
"goVersion": "go1.8.3",
"major": "1",
"minor": "8",
"platform": "linux/amd64"
}
}
$ kubectl describe node master
Name: master
Roles: master
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/hostname=master
node-role.kubernetes.io/master=
Annotations: flannel.alpha.coreos.com/backend-data={"VtepMAC":"86:b6:7a:d6:7b:b3"}
flannel.alpha.coreos.com/backend-type=vxlan
flannel.alpha.coreos.com/kube-subnet-manager=true
flannel.alpha.coreos.com/public-ip=10.0.2.15
node.alpha.kubernetes.io/ttl=0
volumes.kubernetes.io/controller-managed-attach-detach=true
Taints: node-role.kubernetes.io/master:NoSchedule
CreationTimestamp: Sun, 19 Nov 2017 22:27:17 +1100
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
OutOfDisk False Sun, 19 Nov 2017 23:04:56 +1100 Sun, 19 Nov 2017 22:27:13 +1100 KubeletHasSufficientDisk kubelet has sufficient disk space available
MemoryPressure False Sun, 19 Nov 2017 23:04:56 +1100 Sun, 19 Nov 2017 22:27:13 +1100 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Sun, 19 Nov 2017 23:04:56 +1100 Sun, 19 Nov 2017 22:27:13 +1100 KubeletHasNoDiskPressure kubelet has no disk pressure
Ready True Sun, 19 Nov 2017 23:04:56 +1100 Sun, 19 Nov 2017 22:32:24 +1100 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 192.168.99.10
Hostname: master
Capacity:
cpu: 1
memory: 3881880Ki
pods: 110
Allocatable:
cpu: 1
memory: 3779480Ki
pods: 110
System Info:
Machine ID: ca0a351004604dd49e43f8a6258ddd77
System UUID: CA0A3510-0460-4DD4-9E43-F8A6258DDD77
Boot ID: e9060efa-42be-498d-8cb8-8b785b51b247
Kernel Version: 3.10.0-693.el7.x86_64
OS Image: CentOS Linux 7 (Core)
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://1.12.6
Kubelet Version: v1.8.3
Kube-Proxy Version: v1.8.3
PodCIDR: 10.244.0.0/24
ExternalID: master
Non-terminated Pods: (7 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits
--------- ---- ------------ ---------- --------------- -------------
kube-system etcd-master 0 (0%) 0 (0%) 0 (0%) 0 (0%)
kube-system kube-apiserver-master 250m (25%) 0 (0%) 0 (0%) 0 (0%)
kube-system kube-controller-manager-master 200m (20%) 0 (0%) 0 (0%) 0 (0%)
kube-system kube-dns-545bc4bfd4-mqqqk 260m (26%) 0 (0%) 110Mi (2%) 170Mi (4%)
kube-system kube-flannel-ds-hqlnb 0 (0%) 0 (0%) 0 (0%) 0 (0%)
kube-system kube-proxy-t7z5w 0 (0%) 0 (0%) 0 (0%) 0 (0%)
kube-system kube-scheduler-master 100m (10%) 0 (0%) 0 (0%) 0 (0%)
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
CPU Requests CPU Limits Memory Requests Memory Limits
------------ ---------- --------------- -------------
810m (81%) 0 (0%) 110Mi (2%) 170Mi (4%)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 38m kubelet, master Starting kubelet.
Normal NodeAllocatableEnforced 38m kubelet, master Updated Node Allocatable limit across pods
Normal NodeHasSufficientDisk 37m (x8 over 38m) kubelet, master Node master status is now: NodeHasSufficientDisk
Normal NodeHasSufficientMemory 37m (x8 over 38m) kubelet, master Node master status is now: NodeHasSufficientMemory
Normal NodeHasNoDiskPressure 37m (x7 over 38m) kubelet, master Node master status is now: NodeHasNoDiskPressure
Normal Starting 37m kube-proxy, master Starting kube-proxy.
Normal Starting 32m kubelet, master Starting kubelet.
Normal NodeAllocatableEnforced 32m kubelet, master Updated Node Allocatable limit across pods
Normal NodeHasSufficientDisk 32m kubelet, master Node master status is now: NodeHasSufficientDisk
Normal NodeHasSufficientMemory 32m kubelet, master Node master status is now: NodeHasSufficientMemory
Normal NodeHasNoDiskPressure 32m kubelet, master Node master status is now: NodeHasNoDiskPressure
Normal NodeNotReady 32m kubelet, master Node master status is now: NodeNotReady
Normal NodeReady 32m kubelet, master Node master status is now: NodeReady