【kubernetes/k8s概念】k8s 坑问题汇总
1.Pod始终处于Pending状态如果Pod保持在Pending的状态，意味着无法被正常的调度到节点上。由于某种系统资源无法满足Pod运行的需求系统没有足够的资源：已经用尽了集群中所有的CPU或内存资源。需要清理一些不在需要的Pod，调整它们所需的资源量，或者向集群中增加新的节点。用户指定了hostPort：通过hostPort用户能够将服务暴露到指定的主机端口上，会限......
1. Pod始终处于Pending状态
如果Pod保持在Pending的状态，意味着无法被正常的调度到节点上。由于某种系统资源无法满足Pod运行的需求
- 系统没有足够的资源：已经用尽了集群中所有的CPU或内存资源。需要清理一些不在需要的Pod，调整它们所需的资源量，或者向集群中增加新的节点。
- 用户指定了
hostPort：通过hostPort用户能够将服务暴露到指定的主机端口上，会限制Pod能够被调度运行的节点。
2. Pod始终处于Waiting状态
Pod处在Waiting的状态，说明已经被调度到了一个工作节点，却无法在那个节点上运行。可以使用kubectl describe 含有更详细的错误信息。最经常导致Pod始终Waiting的原因是无法下载镜像
3. Pod 处于 CrashLoopBackOff 状态
CrashLoopBackOff 状态说明容器曾经启动了，但又异常退出了。此时 Pod 的 RestartCounts 通常是大于 0
- 容器进程退出
- 健康检查失败退出
- OOMKilled
5. Pod一直崩溃或运行不正常
可以使用kubectl describe以及kubectl logs排查问题，但是这个一般也不确定
情况有：健康检测失败，OOM情况，或者容器运行生命周期结束
6. 集群雪崩需给Kubelet预留资源
从一次集群雪崩看Kubelet资源预留的正确姿势 - WaltonWang's Blog - OSCHINA - 中文开源技术交流社区
Node Allocatable Resource = Node Capacity - Kube-reserved - system-reserved - eviction-threshold
--eviction-hard=memory.available<1024Mi,nodefs.available<10%,nodefs.inodesFree<5% \
--system-reserved=cpu=0.5,memory=1G \ --kube-reserved=cpu=0.5,memory=1G \
--kube-reserved-cgroup=/system.slice/kubelet.service \
--system-reserved-cgroup=/system.slice \
--enforce-node-allocatable=pods,kube-reserved,system-reserved \
7. nfs挂载错误wrong fs type, bad option, bad superblock
根据错误提示，查看/sbin/mount.<type>文件，果然发现没有/sbin/mount.nfs的文件，安装nfs-utils即可
8. kube-apiserver accept4: too many open files
http: Accept error: accept tcp 0.0.0.0:6443: accept4: too many open files; retrying in 1s
查看apiserver进程，lsof -p $pid，发现占用65540个，查看cat /proc/$pid/limits发现限制在65536个，查看占用的一大堆10250的某个kubelet，发现如下错误
perationExecutor.UnmountVolume started for volume "makepool1-web3" (UniqueName: "kubernetes.io/nfs/7be05590-3a46-11e9-906c-20040fedf0bc-makepool1-web3") pod "7be05590-3a46-11e9-906c-20040fedf0bc" (UID: "7be05590-3a46-11e9-906c-20040fedf0bc")
nestedpendingoperations.go:263] Operation for "\"kubernetes.io/nfs/7be05590-3a46-11e9-906c-20040fedf0bc-makepool1-web3\" (\"7be05590-3a46-11e9-906c-20040fedf0bc\")" failed. No retries permitted until 2019-03-07 12:31:28.78976568 +0800 CST m=+7328011.532812666 (durationBeforeRetry 2m2s). Error: "UnmountVolume.TearDown failed for volume \"makepool1-web3\" (UniqueName: \"kubernetes.io/nfs/7be05590-3a46-11e9-906c-20040fedf0bc-makepool1-web3\") pod \"7be05590-3a46-11e9-906c-20040fedf0bc\" (UID: \"7be05590-3a46-11e9-906c-20040fedf0bc\") : Unmount failed: exit status 16\nUnmounting arguments: /var/lib/kubelet/pods/7be05590-3a46-11e9-906c-20040fedf0bc/volumes/kubernetes.io~nfs/makepool1-web3\nOutput: umount.nfs: /var/lib/kubelet/pods/7be05590-3a46-11e9-906c-20040fedf0bc/volumes/kubernetes.io~nfs/makepool1-web3: device is busy\n\n"
目前解决方案：
kubectl delete --grace-period=0 --force
https://github.com/kubernetes/kubernetes/issues/51835
9. Kubernetes Pod无法删除,Docker: Device is busy问题的解决
参考： https://fav.snadn.cn/article/snapshot?id=131#问题发现
查看证书过期时间
openssl x509 -in xxx.crt -text -noout
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 2 (0x2)
Signature Algorithm: sha256WithRSAEncryption
Issuer: CN=master-node-ca@1574650458
Validity
Not Before: Nov 25 01:54:18 2019 GMT
Not After : Nov 24 01:54:18 2020 GMT
10. k8s 证书过期，一年时间，
openssl x509 -in /etc/kubernetes/ssl/kubernetes.csr -noout -text |grep ' Not '
2. 自动轮换 kubelet 证书
注：kubelet证书分为server和client两种， k8s 1.9默认启用了client证书的自动轮换，但server证书自动轮换需要用户开启。方法是：
2.1 增加 kubelet 参数
--feature-gates=RotateKubeletServerCertificate=true
2.2 增加 controller-manager 参数
--experimental-cluster-signing-duration=87600h0m0s
--feature-gates=RotateKubeletServerCertificate=true2.3 创建 rbac 对象
创建rbac对象，允许节点轮换kubelet server证书：
apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: annotations: rbac.authorization.kubernetes.io/autoupdate: "true" labels: kubernetes.io/bootstrapping: rbac-defaults name: system:certificates.k8s.io:certificatesigningrequests:selfnodeserver rules: - apiGroups: - certificates.k8s.io resources: - certificatesigningrequests/selfnodeserver verbs: - create --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: kubeadm:node-autoapprove-certificate-server roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: system:certificates.k8s.io:certificatesigningrequests:selfnodeserver subjects: - apiGroup: rbac.authorization.k8s.io kind: Group name: system:nodes
第二种方法：修改源码kubeadm编译
< kubernetes - 1.14 版本，修改文件 staging/src/k8s.io/client-go/util/cert/cert.go
>= kubernetes - 1.14 版本，修改文件 cmd/kubeadm/app/util/pkiutill/pki-helpers.go
// NewSignedCert creates a signed certificate using the given CA certificate and key
func NewSignedCert(cfg *certutil.Config, key crypto.Signer, caCert *x509.Certificate, caKey crypto.Signer) (*x509.Certificate, error) {
const durationTen = time.Hour * 24 * 355 * 10
certTmpl := x509.Certificate{
Subject: pkix.Name{
CommonName: cfg.CommonName,
Organization: cfg.Organization,
},
DNSNames: cfg.AltNames.DNSNames,
IPAddresses: cfg.AltNames.IPs,
SerialNumber: serial,
NotBefore: caCert.NotBefore,
// NotAfter: time.Now().Add(kubeadmconstants.CertificateValidity).UTC(),
NotAfter: time.Now().Add(durationTen).UTC(),
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: cfg.Usages,
}
编译 make WHAT=cmd/kubeadm GOFLAGES=-v
kubeadm alpha certs renew all --config=/usr/local/install-k8s/core/kubeadm-config.yaml
11. k8s无法删除namespace 提示 Terminating
解决方法：
kubectl get ns ns-xxx-zhangzhonglin-444c6833 -o json > ns-delete.json
删除文件中spec.finalizers字段
"spec": {
},
注：在执行命令前，要先克隆一个新会话，执行 kubectl proxy --port=8081
curl -k -H "Content-Type: application/json" -X PUT --data-binary @ns-delete.json http://127.0.0.1:8081/api/v1/namespaces/ns-xxx-zhangzhonglin-444c6833/finalize
12. Kubernetes: No Route to Host
Error getting server version: Get https://10.200.0.1:443/version?timeout=32s: dial tcp 10.200.0.1:443: connect: no route to host
解决方法： iptables -F
苦
13. kubeadm kube-controller-manager does not have ceph rbd binary anymore
Error: "failed to create rbd image: executable file not found in $PATH, command output: "https://github.com/kubernetes/kubernetes/issues/56990
yum install -y ceph-common
14. monclient: _check_auth_rotating possible clock skew, rotating keys expired way too early (before 2019-05-06 02:00:09.601676)
ceph osd问题，主要是时钟不同步问题
15. helm报这个错误 Helm: Error: no available release name found
因为 tiller没有正确的角色权限
kubectl create serviceaccount --namespace kube-system tiller
kubectl create clusterrolebinding tiller-cluster-rule --clusterrole=cluster-admin --serviceaccount=kube-system:tiller
kubectl patch deploy --namespace kube-system tiller-deploy -p '{"spec":{"template":{"spec":{"serviceAccount":"tiller"}}}}'
16. attachdetach-controller Multi-Attach error for volume "pvc-d0fde86c-8661-11e9-b873-0800271c9f15" Volume is already used by pod
https://github.com/kubernetes/kubernetes/issues/70349
https://github.com/kubernetes/kubernetes/pull/45346
https://github.com/kubernetes/kubernetes/issues/53059
https://github.com/kubernetes/kubernetes/pull/40148
Vsphere Cloud Provider: failed to detach volume from shutdown node #75342
Don't try to attach volumes which are already attached to other nodes #45346
Pods with volumes stuck in ContainerCreating after cluster node is deleted from OpenStack #50200
Don't try to attach volumes which are already attached to other nodes#40148
Pods with volumes stuck in ContainerCreating after cluster node is powered off in vCenter #50944
17. kubelet 挂掉，csi-rbdplugin 依然建在（statefuleset）
18. k8s pv无法删除问题
pv始终处于“Terminating”状态，而且delete不掉
删除k8s中的记录 kubectl patch pv xxx -p '{"metadata":{"finalizers":null}}'
19. Volumes fail to clean up when kubelet restart due to race between actual and desired state #75345
Fix race condition between actual and desired state in kublet volume manager #75458
Pod is stuck in Terminating status forever after Kubelet restart #72604
20. when using ValidatingWebhookConfiguration for deployment subresource(scale) validation. Internal error occurred: converting (extensions.Deployment).Replicas to (v1beta1.Scale).Replicas: Selector not present in src
该问题已经修复，v15版本
https://github.com/kubernetes/kubernetes/pull/76849/commits
21. Error from server: Get https://master-node:10250/containerLogs/default/csi-hostpathplugin-0/node-driver-registrar: dial tcp: lookup master-node on 114.114.114.114:53: no such host
解决方法，在 /etc/hosts 添加 192.168.X.X master-node
22. calico/node is not ready: BIRD is not ready: BGP not established with
主要原因是 calico 傻，没有识别到网卡
modified calico.yaml file to include:
- name: IP_AUTODETECTION_METHOD
value: "interface=ens.*"23. client-go@v11.0.0+incompatible/rest/request.go:598:31: not enough arguments in call to watch.NewStreamWatcher
可以尝试手动替换k8s.io/apimachinery@v0.17.0为k8s.io/apimachinery@release-1.14来解决。在终端执行# go mod download -json k8s.io/apimachinery@release-1.14
24. 无法删除image报rbd: error: image still has watchers解决方法
参考. 无法删除image报rbd: error: image still has watchers解决方法
解决思路：
在Ceph集群日常运维中，管理员可能会遇到有的image删除不了的情况：
1） 由于image下有快照信息，只需要先将快照信息清除，然后再删除该image即可
2） 该image仍旧被一个客户端在访问，具体表现为该image中有watcher。如果该客户端异常了，那么就会出现无法删除该image的情况对于第一种情况，很好解决，下面要说的是第二种情况该如何解决。解决之前先科普一下watcher相关的知识：
Ceph中有一个watch/notify机制(粒度是object)，它用来在不同客户端之间进行消息通知，使得各客户端之间的状态保持一致，而每一个进行watch的客户端，对于Ceph集群来说都是一个watcher。解决方法：
1. 查看当前image上的watcher
查看方法一：
[root@node3 ~]# rbd status foo watcher=192.168.197.157:0/1135656048 client.4172 cookie=1这种查看方法简单快捷，值得推荐
查看方法二：
1） 首先找到image的header对象
[root@node3 ~]# rbd info foo rbd image 'foo': size 1024 MB in 256 objects order 22 (4096 kB objects) block_name_prefix: rbd_data.1041643c9869 format: 2 features: layering flags: create_timestamp: Tue Oct 17 10:20:50 2017由该image的block_name_prefix为 rbd_data.1041643c9869，可知该image的header对象为rbd_header.1041643c9869，得到了header对象后，查看watcher信息
2） 查看该image的header对象上的watcher信息
[root@node3 ~]# rados -p rbd listwatchers rbd_header.1041643c9869 watcher=192.168.197.157:0/1135656048 client.4172 cookie=12. 删除image上的watcher
2.1 把该watcher加入黑名单：
[root@node3 ~]# ceph osd blacklist add 192.168.197.157:0/1135656048 blacklisting 192.168.197.157:0/1135656048 until 2017-10-18 12:04:19.103313 (3600 sec)2.2 查看占用该image的watcher：
[root@node3 ~]# rados -p rbd listwatchers rbd_header.1041643c9869 [root@node3 ~]#异常客户端的watcher信息已经不存在了，之后我们就可以对该image进行删除操作了
2.3 删除该image：
[root@node3 ~]# rbd rm foo Removing image: 100% complete...done.3. 后续操作
实际上做完上面的已经解决了问题，不过最好还是把加入黑名单的客户端移除，下面是有关黑名单的相关操作
3.1 查询黑名单列表：
[root@node3 ~]# ceph osd blacklist ls listed 1 entries 192.168.197.157:0/1135656048 2017-10-18 12:04:19.1033133.2 从黑名单移出一个客户端：
[root@node3 ~]# ceph osd blacklist rm 192.168.197.157:0/1135656048 un-blacklisting 192.168.197.157:0/11356560483.3 清空黑名单：
[root@node3 ~]# ceph osd blacklist clear removed all blacklist entries参考文献
25. x509: subject with cn=metrics-client is not in the allowed list: [aggregator]
请求头部标识不正确，在kube-apiserver中增加配置
--requestheader-allowed-names=aggregator,metrics-client
26. metrics-server 安装问题
unable to fully collect metrics: unable to fully scrape metrics from source kubelet_summary:master-node: unable to fetch metrics from Kubelet master-node (master-node): Get https://master-node:10250/stats/summary/: dial tcp: lookup master-node on 10.200.254.254:53: no such host
- name: tmp-dir
emptyDir: {}
containers:
- name: metrics-server
image: zhangzhonglin/metrics-server-amd64:v0.3.6
imagePullPolicy: IfNotPresent
args:
- --kubelet-preferred-address-types=InternalIP,Hostname
- --kubelet-insecure-tls
- --cert-dir=/tmp
- --secure-port=4443
metrics-server这个容器不能通过CoreDNS 10.200.254.254 解析各Node的主机名，metrics-server连节点时默认是连接节点的主机名，需要加个参数，让它连接节点的IP，同时因为10250是https端口，连接它时需要提供证书，所以加上–kubelet-insecure-tls，表示不验证客户端证书
27. Error from server (Forbidden): Forbidden (user=kubernetes, verb=get, resource=nodes, subresource=proxy)
# kubectl logs aws-node-rvz95 -nkube-system
Error from server (Forbidden): Forbidden (user=kubernetes, verb=get, resource=nodes, subresource=proxy) ( pods/log aws-node-rvz95)
解决方法：
# kubectl create clusterrolebinding kubernetes --clusterrole=cluster-admin --user=kubernetes
clusterrolebinding.rbac.authorization.k8s.io/kubernetes created
28. etcd报错：failed to send out heartbeat on time etcdserver: server is likely overloaded
心跳检测报错主要与磁盘速度、cpu和网络有关
disk运行过慢导致的，leader一般会在心跳包里附带一些metadata，leader需要先把这些数据固化到磁盘上，然后才能发送。写磁盘过程可能要与其他应用竞争，或者因为磁盘是一个虚拟的或者是SATA类型的导致运行过慢，此时只有更好更快磁盘硬件才能解决问题。
CPU计算能力不足
网速过慢，根据机房间的RTT调整heartbeat-interval，而参数election-timeout则至少是heartbeat-interval的5倍
29. etcdserver: applying raft message exceeded backend quota
etcdserver: mvcc: database space exceeded
took (489ns) to execute, err is etcdserver: no space
默认etcd空间配额大小为 2G，超过 2G 将不再写入数据。通过给etcd配置 --quota-backend-bytes 参数增大空间配额，最大支持 8G。
-quota-backend-bytes 8589934592
# get current revision
$ rev=$(ETCDCTL_API=3 etcdctl --endpoints=:2379 endpoint status --write-out="json" | egrep -o '"revision":[0-9]*' | egrep -o '[0-9]*')
# compact away all old revisions
$ ETCDCTL_API=3 etcdctl compact $rev
compacted revision 1516
# defragment away excessive space
$ ETCDCTL_API=3 etcdctl defrag
Finished defragmenting etcd member[127.0.0.1:2379]
# disarm alarm
$ ETCDCTL_API=3 etcdctl alarm disarm
memberID:13803658152347727308 alarm:NOSPACE
# test puts are allowed again
$ ETCDCTL_API=3 etcdctl put newkey 123
OK30. etcdserver: too many requests
如果 Raft 模块已提交的索引（committed index）比已应用到状态机的索引（applied index）多于 5000，就返回 "etcdserver: too many requests" 给 client
提交到 Raft 模块的请求，都会做一些简单的限速判断
31. 无法访问 gcr.io
32. (as uid:107, gid:107): Permission denied
libguestfs: error: could not create appliance through libvirt.
Try running qemu directly without libvirt using this environment variable:
export LIBGUESTFS_BACKEND=direct
Original error from libvirt: Cannot access storage file '/root/-image-build/-image.qcow2' (as uid:107, gid:107): Permission denied [code=38 int1=13]
/etc/libvirt/qemu.conf user=root
33. ceph rbd storageclass无法动态创建pv
创建pvc后，k8s没有自动创建pv，从controller-manager服务的日志中，可以看到相关异常信息：
rbd_util.go:341] rbd: Error creating rbd image: fork/exec /usr/bin/rbd: invalid argument
通过搜索kubernetes官方issue，可以确定是因为使用的ceph管理端key没有经过base64编码，导致无法执行创建image的命令。
34. k8s pod 容器时区
Kubernetes集群中运行的容器默认会使用UTC时间，解决方式：
a. docker镜像里打入
rm -f /etc/localtime && ln -sv /usr/share/zoneinfo/Asia/Shanghai/etc/localtime && echo "Asia/Shanghai">/etc/timezone
b. 通过挂载本地文件
volumeMounts:
- name: tz-config
mountPath: /etc/localtime
volumes:
- name: tz-config
hostPath:
path: /etc/localtimec. 通过环境变量设置时区
env:
- name: TZ
value: Asia/Shanghaid. 通过 PodPreset 设置，k8s v1.20已经移除该功能
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