问题
kubectl（CentOS 7 上为 1.8.3）错误消息的实际含义以及如何解决。任何了解正在发生的事情的参考资料。我想 kubelet 尝试与 docker 对话，但不知何故它没有发生，并且想知道哪些配置是相关的，什么是，以及从 Linux 角度理解哪些概念/机制。
11 月 19 日 22:32:24 master kubelet[4425]: E1119 22:32:24.269786 4425 Summary.go:92] 无法获取“/system.slice/kubelet.service”的系统容器统计信息
：无法获取“/system.slice/kubelet.service”的 cgroup 统计信息“/system.slice/kubelet.service”：无法获取 con
Nov 19 22:32:24 master kubelet[4425]：E1119 22:32:24.269802 4425 Summary.go:92] 无法获取“/”的系统容器统计信息system.slice/docker.service”：无法获取“/system.slice/docker.service”的 cgroup 统计信息：无法获取 conta
研究
发现了同样的错误，并通过更新 kubelet 的服务单元来解决此问题，如下所示，但没有成功。
/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
按照以下步骤设置 Kubernetes 集群安装 kubeadm。文档中的部分安装 Docker关于对齐 cgroup 驱动程序的说明如下。
注意：请确保 kubelet 使用的 cgroup 驱动程序与 Docker 使用的 cgroup 驱动程序相同。为了确保兼容性，您可以更新 Docker，如下所示：
cat << EOF > /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
EOF
但这样做会导致docker服务无法启动：
无法使用文件 /etc/docker/daemon.json 配置 Docker 守护进程：以下指令都被指定为标志”。11
月 19 日 16:55:56 localhost.localdomain systemd1：docker.service：主进程已退出，代码=已退出，状态=1/FAILURE。
Maser 节点已准备就绪，所有系统 Pod 都在运行。
$ 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
环境
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