---
reviewers:
- janetkuo
- thockin
content_type: concept
title: 应用自测与调试
---

<!-- overview -->

<!--
Once your application is running, you'll inevitably need to debug problems with it.
Earlier we described how you can use `kubectl get pods` to retrieve simple status information about
your pods. But there are a number of ways to get even more information about your application.
-->
运行应用时，不可避免的需要定位问题。
前面我们介绍了如何使用 `kubectl get pods` 来查询 pod 的简单信息。
除此之外，还有一系列的方法来获取应用的更详细信息。

<!-- body -->

<!--
## Using `kubectl describe pod` to fetch details about pods
-->
## 使用 `kubectl describe pod` 命令获取 Pod 详情

<!--
For this example we'll use a Deployment to create two pods, similar to the earlier example.
-->
与之前的例子类似，我们使用一个 Deployment 来创建两个 Pod。

{{< codenew file="application/nginx-with-request.yaml" >}}

<!--
Create deployment by running following command:
-->
使用如下命令创建 Deployment：

```shell
kubectl apply -f https://k8s.io/examples/application/nginx-with-request.yaml
```

```
deployment.apps/nginx-deployment created
```

<!--
Check pod status by following command:
-->
使用如下命令查看 Pod 状态：

```shell
kubectl get pods
```

```
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-1006230814-6winp   1/1       Running   0          11s
nginx-deployment-1006230814-fmgu3   1/1       Running   0          11s
```

<!--
We can retrieve a lot more information about each of these pods using `kubectl describe pod`. For example:
-->
我们可以使用 `kubectl describe pod` 命令来查询每个 Pod 的更多信息，比如：

```shell
kubectl describe pod nginx-deployment-1006230814-6winp
```

```
Name:		nginx-deployment-1006230814-6winp
Namespace:	default
Node:		kubernetes-node-wul5/10.240.0.9
Start Time:	Thu, 24 Mar 2016 01:39:49 +0000
Labels:		app=nginx,pod-template-hash=1006230814
Annotations:    kubernetes.io/created-by={"kind":"SerializedReference","apiVersion":"v1","reference":{"kind":"ReplicaSet","namespace":"default","name":"nginx-deployment-1956810328","uid":"14e607e7-8ba1-11e7-b5cb-fa16" ...
Status:		Running
IP:		10.244.0.6
Controllers:	ReplicaSet/nginx-deployment-1006230814
Containers:
  nginx:
    Container ID:	docker://90315cc9f513c724e9957a4788d3e625a078de84750f244a40f97ae355eb1149
    Image:		nginx
    Image ID:		docker://6f62f48c4e55d700cf3eb1b5e33fa051802986b77b874cc351cce539e5163707
    Port:		80/TCP
    QoS Tier:
      cpu:	Guaranteed
      memory:	Guaranteed
    Limits:
      cpu:	500m
      memory:	128Mi
    Requests:
      memory:		128Mi
      cpu:		500m
    State:		Running
      Started:		Thu, 24 Mar 2016 01:39:51 +0000
    Ready:		True
    Restart Count:	0
    Environment:        <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-5kdvl (ro)
Conditions:
  Type          Status
  Initialized   True
  Ready         True
  PodScheduled  True
Volumes:
  default-token-4bcbi:
    Type:	Secret (a volume populated by a Secret)
    SecretName:	default-token-4bcbi
    Optional:   false
QoS Class:      Guaranteed
Node-Selectors: <none>
Tolerations:    <none>
Events:
  FirstSeen	LastSeen	Count	From					SubobjectPath		Type		Reason		Message
  ---------	--------	-----	----					-------------		--------	------		-------
  54s		54s		1	{default-scheduler }						Normal		Scheduled	Successfully assigned nginx-deployment-1006230814-6winp to kubernetes-node-wul5
  54s		54s		1	{kubelet kubernetes-node-wul5}	spec.containers{nginx}	Normal		Pulling		pulling image "nginx"
  53s		53s		1	{kubelet kubernetes-node-wul5}	spec.containers{nginx}	Normal		Pulled		Successfully pulled image "nginx"
  53s		53s		1	{kubelet kubernetes-node-wul5}	spec.containers{nginx}	Normal		Created		Created container with docker id 90315cc9f513
  53s		53s		1	{kubelet kubernetes-node-wul5}	spec.containers{nginx}	Normal		Started		Started container with docker id 90315cc9f513
```

<!--
Here you can see configuration information about the container(s) and Pod (labels, resource requirements, etc.), 
as well as status information about the container(s) and Pod (state, readiness, restart count, events, etc.).
-->
这里可以看到容器和 Pod 的标签、资源需求等配置信息，还可以看到状态、就绪态、
重启次数、事件等状态信息。

<!--
The container state is one of Waiting, Running, or Terminated. 
Depending on the state, additional information will be provided -- here you can see that for a container in Running state, the system tells you when the container started.
-->
容器状态是 Waiting、Running 和 Terminated 之一。
根据状态的不同，还有对应的额外的信息 —— 在这里你可以看到，
对于处于运行状态的容器，系统会告诉你容器的启动时间。

<!--
Ready tells you whether the container passed its last readiness probe. 
(In this case, the container does not have a readiness probe configured; the container is assumed to be ready if no readiness probe is configured.)
-->
Ready 指示是否通过了最后一个就绪态探测。
(在本例中，容器没有配置就绪态探测；如果没有配置就绪态探测，则假定容器已经就绪。)

<!--
Restart Count tells you how many times the container has been restarted; 
this information can be useful for detecting crash loops in containers that are configured with a restart policy of 'always.'
-->
Restart Count 告诉你容器已重启的次数；
这些信息对于定位配置了 “Always” 重启策略的容器持续崩溃问题非常有用。

<!--
Currently the only Condition associated with a Pod is the binary Ready condition, 
which indicates that the pod is able to service requests and should be added to the load balancing pools of all matching services.
-->
目前，唯一与 Pod 有关的状态是 Ready 状况，该状况表明 Pod 能够为请求提供服务，
并且应该添加到相应服务的负载均衡池中。

<!--
Lastly, you see a log of recent events related to your Pod. 
The system compresses multiple identical events by indicating the first and last time it was seen and the number of times it was seen. 
"From" indicates the component that is logging the event, 
"SubobjectPath" tells you which object (e.g. container within the pod) is being referred to, 
and "Reason" and "Message" tell you what happened.
-->
最后，你还可以看到与 Pod 相关的近期事件。
系统通过指示第一次和最后一次看到事件以及看到该事件的次数来压缩多个相同的事件。
“From” 标明记录事件的组件，
“SubobjectPath” 告诉你引用了哪个对象（例如 Pod 中的容器），
“Reason” 和 “Message” 告诉你发生了什么。

<!--
## Example: debugging Pending Pods

A common scenario that you can detect using events is when you've created a Pod that won't fit on any node. 
For example, the Pod might request more resources than are free on any node, 
or it might specify a label selector that doesn't match any nodes. 
Let's say we created the previous Deployment with 5 replicas (instead of 2) and requesting 600 millicores instead of 500, 
on a four-node cluster where each (virtual) machine has 1 CPU. 
In that case one of the Pods will not be able to schedule. 
(Note that because of the cluster addon pods such as fluentd, skydns, etc., that run on each node, if we requested 1000 millicores then none of the Pods would be able to schedule.)
-->
## 例子: 调试 Pending 状态的 Pod

可以使用事件来调试的一个常见的场景是，你创建 Pod 无法被调度到任何节点。
比如，Pod 请求的资源比较多，没有任何一个节点能够满足，或者它指定了一个标签，没有节点可匹配。
假定我们创建之前的 Deployment 时指定副本数是 5（不再是 2），并且请求 600 毫核（不再是 500），
对于一个 4 个节点的集群，若每个节点只有 1 个 CPU，这时至少有一个 Pod 不能被调度。
（需要注意的是，其他集群插件 Pod，比如 fluentd、skydns 等等会在每个节点上运行，
如果我们需求 1000 毫核，将不会有 Pod 会被调度。）

```shell
kubectl get pods
```

```
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-1006230814-6winp   1/1       Running   0          7m
nginx-deployment-1006230814-fmgu3   1/1       Running   0          7m
nginx-deployment-1370807587-6ekbw   1/1       Running   0          1m
nginx-deployment-1370807587-fg172   0/1       Pending   0          1m
nginx-deployment-1370807587-fz9sd   0/1       Pending   0          1m
```

<!--
To find out why the nginx-deployment-1370807587-fz9sd pod is not running, we can use `kubectl describe pod` on the pending Pod and look at its events:
-->
为了查找 Pod nginx-deployment-1370807587-fz9sd 没有运行的原因，我们可以使用
`kubectl describe pod` 命令描述 Pod，查看其事件：

```shell
kubectl describe pod nginx-deployment-1370807587-fz9sd
```

```
  Name:		nginx-deployment-1370807587-fz9sd
  Namespace:	default
  Node:		/
  Labels:		app=nginx,pod-template-hash=1370807587
  Status:		Pending
  IP:
  Controllers:	ReplicaSet/nginx-deployment-1370807587
  Containers:
    nginx:
      Image:	nginx
      Port:	80/TCP
      QoS Tier:
        memory:	Guaranteed
        cpu:	Guaranteed
      Limits:
        cpu:	1
        memory:	128Mi
      Requests:
        cpu:	1
        memory:	128Mi
      Environment Variables:
  Volumes:
    default-token-4bcbi:
      Type:	Secret (a volume populated by a Secret)
      SecretName:	default-token-4bcbi
  Events:
    FirstSeen	LastSeen	Count	From			        SubobjectPath	Type		Reason			    Message
    ---------	--------	-----	----			        -------------	--------	------			    -------
    1m		    48s		    7	    {default-scheduler }			        Warning		FailedScheduling	pod (nginx-deployment-1370807587-fz9sd) failed to fit in any node
  fit failure on node (kubernetes-node-6ta5): Node didn't have enough resource: CPU, requested: 1000, used: 1420, capacity: 2000
  fit failure on node (kubernetes-node-wul5): Node didn't have enough resource: CPU, requested: 1000, used: 1100, capacity: 2000
```

<!--
Here you can see the event generated by the scheduler saying that the Pod failed to schedule for reason `FailedScheduling` (and possibly others).  
The message tells us that there were not enough resources for the Pod on any of the nodes.
-->
这里你可以看到由调度器记录的事件，它表明了 Pod 不能被调度的原因是 `FailedScheduling`（也可能是其他值）。
其 message 部分表明没有任何节点拥有足够多的资源。

<!--
To correct this situation, you can use `kubectl scale` to update your Deployment to specify four or fewer replicas. 
(Or you could just leave the one Pod pending, which is harmless.)
-->
要纠正这种情况，可以使用 `kubectl scale` 更新 Deployment，以指定 4 个或更少的副本。
(或者你可以让 Pod 继续保持这个状态，这是无害的。)

<!--
Events such as the ones you saw at the end of `kubectl describe pod` are persisted in etcd and 
provide high-level information on what is happening in the cluster. 
To list all events you can use
-->
你在 `kubectl describe pod` 结尾处看到的事件都保存在 etcd 中，
并提供关于集群中正在发生的事情的高级信息。
如果需要列出所有事件，可使用命令：

```shell
kubectl get events
```

<!--
but you have to remember that events are namespaced. 
This means that if you're interested in events for some namespaced object 
(e.g. what happened with Pods in namespace `my-namespace`) you need to explicitly provide a namespace to the command:
-->
但是，需要注意的是，事件是区分名字空间的。
如果你对某些名字空间域的对象（比如 `my-namespace` 名字下的 Pod）的事件感兴趣,
你需要显式地在命令行中指定名字空间：

```shell
kubectl get events --namespace=my-namespace
```

<!--
To see events from all namespaces, you can use the `--all-namespaces` argument.
-->
查看所有 namespace 的事件，可使用 `--all-namespaces` 参数。

<!--
In addition to `kubectl describe pod`, another way to get extra information about a pod (beyond what is provided by `kubectl get pod`) is 
to pass the `-o yaml` output format flag to `kubectl get pod`. 
This will give you, in YAML format, even more information than `kubectl describe pod`--essentially all of the information the system has about the Pod. 
Here you will see things like annotations (which are key-value metadata without the label restrictions, that is used internally by Kubernetes system components), 
restart policy, ports, and volumes.
-->
除了 `kubectl describe pod` 以外，另一种获取 Pod 额外信息（除了 `kubectl get pod`）的方法
是给 `kubectl get pod` 增加 `-o yaml` 输出格式参数。
该命令将以 YAML 格式为你提供比 `kubectl describe pod` 更多的信息 —— 实际上是系统拥有的关于 Pod 的所有信息。
在这里，你将看到注解（没有标签限制的键值元数据，由 Kubernetes 系统组件在内部使用）、
重启策略、端口和卷等。

```shell
kubectl get pod nginx-deployment-1006230814-6winp -o yaml
```

```yaml
apiVersion: v1
kind: Pod
metadata:
  annotations:
    kubernetes.io/created-by: |
      {"kind":"SerializedReference","apiVersion":"v1","reference":{"kind":"ReplicaSet","namespace":"default","name":"nginx-deployment-1006230814","uid":"4c84c175-f161-11e5-9a78-42010af00005","apiVersion":"extensions","resourceVersion":"133434"}}
  creationTimestamp: 2016-03-24T01:39:50Z
  generateName: nginx-deployment-1006230814-
  labels:
    app: nginx
    pod-template-hash: "1006230814"
  name: nginx-deployment-1006230814-6winp
  namespace: default
  resourceVersion: "133447"
  uid: 4c879808-f161-11e5-9a78-42010af00005
spec:
  containers:
  - image: nginx
    imagePullPolicy: Always
    name: nginx
    ports:
    - containerPort: 80
      protocol: TCP
    resources:
      limits:
        cpu: 500m
        memory: 128Mi
      requests:
        cpu: 500m
        memory: 128Mi
    terminationMessagePath: /dev/termination-log
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: default-token-4bcbi
      readOnly: true
  dnsPolicy: ClusterFirst
  nodeName: kubernetes-node-wul5
  restartPolicy: Always
  securityContext: {}
  serviceAccount: default
  serviceAccountName: default
  terminationGracePeriodSeconds: 30
  volumes:
  - name: default-token-4bcbi
    secret:
      secretName: default-token-4bcbi
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: 2016-03-24T01:39:51Z
    status: "True"
    type: Ready
  containerStatuses:
  - containerID: docker://90315cc9f513c724e9957a4788d3e625a078de84750f244a40f97ae355eb1149
    image: nginx
    imageID: docker://6f62f48c4e55d700cf3eb1b5e33fa051802986b77b874cc351cce539e5163707
    lastState: {}
    name: nginx
    ready: true
    restartCount: 0
    state:
      running:
        startedAt: 2016-03-24T01:39:51Z
  hostIP: 10.240.0.9
  phase: Running
  podIP: 10.244.0.6
  startTime: 2016-03-24T01:39:49Z
```

<!--
## Example: debugging a down/unreachable node

Sometimes when debugging it can be useful to look at the status of a node 
-- for example, because you've noticed strange behavior of a Pod that's running on the node, 
or to find out why a Pod won't schedule onto the node. 
As with Pods, you can use `kubectl describe node` and `kubectl get node -o yaml` to 
retrieve detailed information about nodes. 
For example, here's what you'll see if a node is down 
(disconnected from the network, or kubelet dies and won't restart, etc.). 
Notice the events that show the node is NotReady, and 
also notice that the pods are no longer running 
(they are evicted after five minutes of NotReady status).
-->
## 示例：调试宕机或无法联系的节点

有时候，在调试时，查看节点的状态是很有用的 —— 例如，因为你已经注意到节点上运行的 Pod 的奇怪行为，
或者想了解为什么 Pod 不会调度到节点上。
与 Pod 一样，你可以使用 `kubectl describe node` 和 `kubectl get node -o yaml` 来查询节点的详细信息。
例如，如果某个节点宕机（与网络断开连接，或者 kubelet 挂掉无法重新启动等等），你将看到以下情况。
请注意显示节点未就绪的事件，也请注意 Pod 不再运行(它们在5分钟未就绪状态后被驱逐)。

```shell
kubectl get nodes
```

```
NAME                     STATUS       ROLES     AGE     VERSION
kubernetes-node-861h     NotReady     <none>    1h      v1.13.0
kubernetes-node-bols     Ready        <none>    1h      v1.13.0
kubernetes-node-st6x     Ready        <none>    1h      v1.13.0
kubernetes-node-unaj     Ready        <none>    1h      v1.13.0
```

```shell
kubectl describe node kubernetes-node-861h
```

```none
Name:			kubernetes-node-861h
Role
Labels:		 kubernetes.io/arch=amd64
           kubernetes.io/os=linux
           kubernetes.io/hostname=kubernetes-node-861h
Annotations:        node.alpha.kubernetes.io/ttl=0
                    volumes.kubernetes.io/controller-managed-attach-detach=true
Taints:             <none>
CreationTimestamp:	Mon, 04 Sep 2017 17:13:23 +0800
Phase:
Conditions:
  Type		Status		LastHeartbeatTime			LastTransitionTime			Reason					Message
  ----    ------    -----------------     ------------------      ------          -------
  OutOfDisk             Unknown         Fri, 08 Sep 2017 16:04:28 +0800         Fri, 08 Sep 2017 16:20:58 +0800         NodeStatusUnknown       Kubelet stopped posting node status.
  MemoryPressure        Unknown         Fri, 08 Sep 2017 16:04:28 +0800         Fri, 08 Sep 2017 16:20:58 +0800         NodeStatusUnknown       Kubelet stopped posting node status.
  DiskPressure          Unknown         Fri, 08 Sep 2017 16:04:28 +0800         Fri, 08 Sep 2017 16:20:58 +0800         NodeStatusUnknown       Kubelet stopped posting node status.
  Ready                 Unknown         Fri, 08 Sep 2017 16:04:28 +0800         Fri, 08 Sep 2017 16:20:58 +0800         NodeStatusUnknown       Kubelet stopped posting node status.
Addresses:	10.240.115.55,104.197.0.26
Capacity:
 cpu:           2
 hugePages:     0
 memory:        4046788Ki
 pods:          110
Allocatable:
 cpu:           1500m
 hugePages:     0
 memory:        1479263Ki
 pods:          110
System Info:
 Machine ID:                    8e025a21a4254e11b028584d9d8b12c4
 System UUID:                   349075D1-D169-4F25-9F2A-E886850C47E3
 Boot ID:                       5cd18b37-c5bd-4658-94e0-e436d3f110e0
 Kernel Version:                4.4.0-31-generic
 OS Image:                      Debian GNU/Linux 8 (jessie)
 Operating System:              linux
 Architecture:                  amd64
 Container Runtime Version:     docker://1.12.5
 Kubelet Version:               v1.6.9+a3d1dfa6f4335
 Kube-Proxy Version:            v1.6.9+a3d1dfa6f4335
ExternalID:                     15233045891481496305
Non-terminated Pods:            (9 in total)
  Namespace                     Name                                            CPU Requests    CPU Limits      Memory Requests Memory Limits
  ---------                     ----                                            ------------    ----------      --------------- -------------
......
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  CPU Requests  CPU Limits      Memory Requests         Memory Limits
  ------------  ----------      ---------------         -------------
  900m (60%)    2200m (146%)    1009286400 (66%)        5681286400 (375%)
Events:         <none>
```

```shell
kubectl get node kubernetes-node-861h -o yaml
```

```yaml
apiVersion: v1
kind: Node
metadata:
  creationTimestamp: 2015-07-10T21:32:29Z
  labels:
    kubernetes.io/hostname: kubernetes-node-861h
  name: kubernetes-node-861h
  resourceVersion: "757"
  selfLink: /api/v1/nodes/kubernetes-node-861h
  uid: 2a69374e-274b-11e5-a234-42010af0d969
spec:
  externalID: "15233045891481496305"
  podCIDR: 10.244.0.0/24
  providerID: gce://striped-torus-760/us-central1-b/kubernetes-node-861h
status:
  addresses:
  - address: 10.240.115.55
    type: InternalIP
  - address: 104.197.0.26
    type: ExternalIP
  capacity:
    cpu: "1"
    memory: 3800808Ki
    pods: "100"
  conditions:
  - lastHeartbeatTime: 2015-07-10T21:34:32Z
    lastTransitionTime: 2015-07-10T21:35:15Z
    reason: Kubelet stopped posting node status.
    status: Unknown
    type: Ready
  nodeInfo:
    bootID: 4e316776-b40d-4f78-a4ea-ab0d73390897
    containerRuntimeVersion: docker://Unknown
    kernelVersion: 3.16.0-0.bpo.4-amd64
    kubeProxyVersion: v0.21.1-185-gffc5a86098dc01
    kubeletVersion: v0.21.1-185-gffc5a86098dc01
    machineID: ""
    osImage: Debian GNU/Linux 7 (wheezy)
    systemUUID: ABE5F6B4-D44B-108B-C46A-24CCE16C8B6E
```

## {{% heading "whatsnext" %}}

<!--
Learn about additional debugging tools, including:
-->
了解更多的调试工具：

<!--
* [Logging](/docs/concepts/cluster-administration/logging/)
* [Monitoring](/docs/tasks/debug-application-cluster/resource-usage-monitoring/)
* [Getting into containers via `exec`](/docs/tasks/debug-application-cluster/get-shell-running-container/)
* [Connecting to containers via proxies](/docs/tasks/extend-kubernetes/http-proxy-access-api/)
* [Connecting to containers via port forwarding](/docs/tasks/access-application-cluster/port-forward-access-application-cluster/)
* [Inspect Kubernetes node with crictl](/docs/tasks/debug-application-cluster/crictl/)
-->
* [日志](/zh/docs/concepts/cluster-administration/logging/)
* [监控](/zh/docs/tasks/debug-application-cluster/resource-usage-monitoring/)
* [使用 `exec` 进入容器](/zh/docs/tasks/debug-application-cluster/get-shell-running-container/)
* [使用代理连接容器](/zh/docs/tasks/extend-kubernetes/http-proxy-access-api/)
* [使用端口转发连接容器](/zh/docs/tasks/access-application-cluster/port-forward-access-application-cluster/)
* [使用 crictl 检查节点](/zh/docs/tasks/debug-application-cluster/crictl/)

