*** PLEASE NOTE: This document applies to the HEAD of the source
tree only. If you are using a released version of Kubernetes, you almost
certainly want the docs that go with that version.
Documentation for specific releases can be found at
[releases.k8s.io](http://releases.k8s.io).
## Overview
This example shows two types of pod health checks: HTTP checks and container execution checks.
The [exec-liveness.yaml](exec-liveness.yaml) demonstrates the container execution check.
```
livenessProbe:
exec:
command:
- cat
- /tmp/health
initialDelaySeconds: 15
timeoutSeconds: 1
```
Kubelet executes the command cat /tmp/health in the container and reports failure if the command returns a non-zero exit code.
Note that the container removes the /tmp/health file after 10 seconds,
```
echo ok > /tmp/health; sleep 10; rm -rf /tmp/health; sleep 600
```
so when Kubelet executes the health check 15 seconds (defined by initialDelaySeconds) after the container started, the check would fail.
The [http-liveness.yaml](http-liveness.yaml) demonstrates the HTTP check.
```
livenessProbe:
httpGet:
path: /healthz
port: 8080
initialDelaySeconds: 15
timeoutSeconds: 1
```
The Kubelet sends a HTTP request to the specified path and port to perform the health check. If you take a look at image/server.go, you will see the server starts to respond with an error code 500 after 10 seconds, so the check fails.
This [guide](../walkthrough/k8s201.md#health-checking) has more information on health checks.
## Get your hands dirty
To show the health check is actually working, first create the pods:
```
# kubectl create -f exec-liveness.yaml
# kubectl create -f http-liveness.yaml
```
Check the status of the pods once they are created:
```
# kubectl get pods
NAME READY STATUS RESTARTS AGE
[...]
liveness-exec 1/1 Running 0 13s
liveness-http 1/1 Running 0 13s
```
Check the status half a minute later, you will see the container restart count being incremented:
```
# kubectl get pods
mwielgus@mwielgusd:~/test/k2/kubernetes/examples/liveness$ kubectl get pods
NAME READY STATUS RESTARTS AGE
[...]
liveness-exec 1/1 Running 1 36s
liveness-http 1/1 Running 1 36s
```
At the bottom of the *kubectl describe* output there are messages indicating that the liveness probes have failed, and the containers have been killed and recreated.
```
# kubectl describe pods liveness-exec
[...]
Sat, 27 Jun 2015 13:43:03 +0200 Sat, 27 Jun 2015 13:44:34 +0200 4 {kubelet kubernetes-minion-6fbi} spec.containers{liveness} unhealthy Liveness probe failed: cat: can't open '/tmp/health': No such file or directory
Sat, 27 Jun 2015 13:44:44 +0200 Sat, 27 Jun 2015 13:44:44 +0200 1 {kubelet kubernetes-minion-6fbi} spec.containers{liveness} killing Killing with docker id 65b52d62c635
Sat, 27 Jun 2015 13:44:44 +0200 Sat, 27 Jun 2015 13:44:44 +0200 1 {kubelet kubernetes-minion-6fbi} spec.containers{liveness} created Created with docker id ed6bb004ee10
Sat, 27 Jun 2015 13:44:44 +0200 Sat, 27 Jun 2015 13:44:44 +0200 1 {kubelet kubernetes-minion-6fbi} spec.containers{liveness} started Started with docker id ed6bb004ee10
```
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