Kubernetes:如何调试CrashLoopBackOff

Question

我有以下设置:

omg/telperiondocker hub上的docker 镜像一个kubernetes集群(有4个节点,每个节点有~50GB RAM)和充足的资源

我按照教程将图像从dockerhub拉到kubernetes

SERVICE_NAME=telperion
DOCKER_SERVER="https://index.docker.io/v1/"
DOCKER_USERNAME=username
DOCKER_PASSWORD=password
DOCKER_EMAIL="omg@whatever.com"

# Create secret
kubectl create secret docker-registry dockerhub --docker-server=$DOCKER_SERVER --docker-username=$DOCKER_USERNAME --docker-password=$DOCKER_PASSWORD --docker-email=$DOCKER_EMAIL

# Create service yaml
echo "apiVersion: v1 \n\
kind: Pod \n\
metadata: \n\
  name: ${SERVICE_NAME} \n\
spec: \n\
  containers: \n\
    - name: ${SERVICE_NAME} \n\
      image: omg/${SERVICE_NAME} \n\
      imagePullPolicy: Always \n\
      command: [ \"echo\",\"done deploying $SERVICE_NAME\" ] \n\
  imagePullSecrets: \n\
    - name: dockerhub" > $SERVICE_NAME.yaml

 # Deploy to kubernetes
 kubectl create -f $SERVICE_NAME.yaml

这导致pod进入了 CrashLoopBackoff

docker run -it -p8080:9546 omg/telperion 工作良好.

所以我的问题 是这个可以调试吗？如果是的话,我该怎么调试呢？

一些日志:

kubectl get nodes                                                                                          
NAME                    STATUS                     AGE       VERSION
k8s-agent-adb12ed9-0    Ready                      22h       v1.6.6
k8s-agent-adb12ed9-1    Ready                      22h       v1.6.6
k8s-agent-adb12ed9-2    Ready                      22h       v1.6.6
k8s-master-adb12ed9-0   Ready,SchedulingDisabled   22h       v1.6.6

.

kubectl get pods                                                                                               
NAME                        READY     STATUS             RESTARTS   AGE
telperion                    0/1       CrashLoopBackOff   10         28m

.

kubectl describe pod telperion
Name:           telperion
Namespace:      default
Node:           k8s-agent-adb12ed9-2/10.240.0.4
Start Time:     Wed, 21 Jun 2017 10:18:23 +0000
Labels:         <none>
Annotations:    <none>
Status:         Running
IP:             10.244.1.4
Controllers:    <none>
Containers:
  telperion:
    Container ID:       docker://c2dd021b3d619d1d4e2afafd7a71070e1e43132563fdc370e75008c0b876d567
    Image:              omg/telperion
    Image ID:           docker-pullable://omg/telperion@sha256:c7e3beb0457b33cd2043c62ea7b11ae44a5629a5279a88c086ff4853828a6d96
    Port:
    Command:
      echo
      done deploying telperion
    State:              Waiting
      Reason:           CrashLoopBackOff
    Last State:         Terminated
      Reason:           Completed
      Exit Code:        0
      Started:          Wed, 21 Jun 2017 10:19:25 +0000
      Finished:         Wed, 21 Jun 2017 10:19:25 +0000
    Ready:              False
    Restart Count:      3
    Environment:        <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-n7ll0 (ro)
Conditions:
  Type          Status
  Initialized   True
  Ready         False
  PodScheduled  True
Volumes:
  default-token-n7ll0:
    Type:       Secret (a volume populated by a Secret)
    SecretName: default-token-n7ll0
    Optional:   false
QoS Class:      BestEffort
Node-Selectors: <none>
Tolerations:    <none>
Events:
  FirstSeen     LastSeen        Count   From                            SubObjectPath                                   Type            Reason          Message
  ---------     --------        -----   ----                            -------------                                   --------        ------          -------
  1m            1m              1       default-scheduler                                                               Normal          Scheduled       Successfully assigned telperion to k8s-agent-adb12ed9-2
  1m            1m              1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal          Created         Created container with id d9aa21fd16b682698235e49adf80366f90d02628e7ed5d40a6e046aaaf7bf774
  1m            1m              1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal          Started         Started container with id d9aa21fd16b682698235e49adf80366f90d02628e7ed5d40a6e046aaaf7bf774
  1m            1m              1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal          Started         Started container with id c6c8f61016b06d0488e16bbac0c9285fed744b933112fd5d116e3e41c86db919
  1m            1m              1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal          Created         Created container with id c6c8f61016b06d0488e16bbac0c9285fed744b933112fd5d116e3e41c86db919
  1m            1m              2       kubelet, k8s-agent-adb12ed9-2                                                   Warning         FailedSync      Error syncing pod, skipping: failed to "StartContainer" for "telperion" with CrashLoopBackOff: "Back-off 10s restarting failed container=telperion pod=telperion_default(f4e36a12-566a-11e7-99a6-000d3aa32f49)"

  1m    1m      1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal  Started         Started container with id 3b911f1273518b380bfcbc71c9b7b770826c0ce884ac876fdb208e7c952a4631
  1m    1m      1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal  Created         Created container with id 3b911f1273518b380bfcbc71c9b7b770826c0ce884ac876fdb208e7c952a4631
  1m    1m      2       kubelet, k8s-agent-adb12ed9-2                                                   Warning FailedSync      Error syncing pod, skipping: failed to "StartContainer" for "telperion" with CrashLoopBackOff: "Back-off 20s restarting failed container=telperion pod=telperion_default(f4e36a12-566a-11e7-99a6-000d3aa32f49)"

  1m    50s     4       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal  Pulling         pulling image "omg/telperion"
  47s   47s     1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal  Started         Started container with id c2dd021b3d619d1d4e2afafd7a71070e1e43132563fdc370e75008c0b876d567
  1m    47s     4       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal  Pulled          Successfully pulled image "omg/telperion"
  47s   47s     1       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Normal  Created         Created container with id c2dd021b3d619d1d4e2afafd7a71070e1e43132563fdc370e75008c0b876d567
  1m    9s      8       kubelet, k8s-agent-adb12ed9-2   spec.containers{telperion}      Warning BackOff         Back-off restarting failed container
  46s   9s      4       kubelet, k8s-agent-adb12ed9-2                                                   Warning FailedSync      Error syncing pod, skipping: failed to "StartContainer" for "telperion" with CrashLoopBackOff: "Back-off 40s restarting failed container=telperion pod=telperion_default(f4e36a12-566a-11e7-99a6-000d3aa32f49)"

编辑1:kubelet在master上报告的错误:

journalctl -u kubelet

.

Jun 21 10:28:49 k8s-master-ADB12ED9-0 docker[1622]: E0621 10:28:49.798140    1809 fsHandler.go:121] failed to collect filesystem stats - rootDiskErr: du command failed on /var/lib/docker/overlay/5cfff16d670f2df6520360595d7858fb5d16607b6999a88e5dcbc09e1e7ab9ce with output
Jun 21 10:28:49 k8s-master-ADB12ED9-0 docker[1622]: , stderr: du: cannot access '/var/lib/docker/overlay/5cfff16d670f2df6520360595d7858fb5d16607b6999a88e5dcbc09e1e7ab9ce/merged/proc/13122/task/13122/fd/4': No such file or directory
Jun 21 10:28:49 k8s-master-ADB12ED9-0 docker[1622]: du: cannot access '/var/lib/docker/overlay/5cfff16d670f2df6520360595d7858fb5d16607b6999a88e5dcbc09e1e7ab9ce/merged/proc/13122/task/13122/fdinfo/4': No such file or directory
Jun 21 10:28:49 k8s-master-ADB12ED9-0 docker[1622]: du: cannot access '/var/lib/docker/overlay/5cfff16d670f2df6520360595d7858fb5d16607b6999a88e5dcbc09e1e7ab9ce/merged/proc/13122/fd/3': No such file or directory
Jun 21 10:28:49 k8s-master-ADB12ED9-0 docker[1622]: du: cannot access '/var/lib/docker/overlay/5cfff16d670f2df6520360595d7858fb5d16607b6999a88e5dcbc09e1e7ab9ce/merged/proc/13122/fdinfo/3': No such file or directory
Jun 21 10:28:49 k8s-master-ADB12ED9-0 docker[1622]:  - exit status 1, rootInodeErr: <nil>, extraDiskErr: <nil>

编辑2:更多日志

kubectl logs $SERVICE_NAME -p                                                                                                    
done deploying telperion

Answer 1

您可以使用访问pod的日志

kubectl logs [podname] -p

-p选项将读取上一个(崩溃的)实例的日志

如果崩溃来自应用程序,那么您应该有有用的日志.

Answer 2

CrashLoopBackOff告诉 Pod 在启动后立即崩溃。Kubernetes 尝试再次启动 pod，但 pod 再次崩溃，这进入了循环。

您可以通过以下方式检查 Pod 日志是否有任何错误 kubectl logs <pod-name> -n <namespace> --previous

--previous 将向您显示容器先前实例化的日志

接下来，您可以通过描述 pod kubectl describe pod -n 来查看“状态原因”、“最后状态原因”和“事件”部分

“状态原因”，“最后状态原因”

有时问题可能是因为提供给应用程序的内存或 CPU 较少。