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Merge pull request #8200 from caesarxuchao/liveness-example

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update example/liveness to v1beta3
This commit is contained in:
Nikhil Jindal
2015-05-15 14:33:25 -07:00
parent 5888982e74 2dcecf1f65
commit 6dc309b3cf
6 changed files with 117 additions and 94 deletions
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4
examples/examples_test.go
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@@ -170,6 +170,10 @@ func TestExampleObjectSchemas(t *testing.T) {
"glusterfs-pod": &api.Pod{},
"glusterfs-endpoints": &api.Endpoints{},
},
"../examples/liveness": {
"exec-liveness": &api.Pod{},
"http-liveness": &api.Pod{},
},
"../examples": {
"pod": &api.Pod{},
"replication": &api.ReplicationController{},

76
examples/liveness/README.md Normal file
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@@ -0,0 +1,76 @@
## 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](https://github.com/GoogleCloudPlatform/kubernetes/blob/master/examples/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:
```
# cluster/kubectl.sh create -f exec-liveness.yaml
# cluster/kbuectl.sh create -f http-liveness.yaml
```
Check the status of the pods once they are created:
```
# cluster/kubectl.sh get pods
POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
liveness-exec 10.244.3.7 kubernetes-minion-f08h/130.211.122.180 test=liveness Running 3 seconds
liveness gcr.io/google_containers/busybox Running 2 seconds
liveness-http 10.244.0.8 kubernetes-minion-0bks/104.197.10.10 test=liveness Running 3 seconds
liveness gcr.io/google_containers/liveness Running 2 seconds
```
Check the status half a minute later, you will see the termination messages:
```
# cluster/kubectl.sh get pods
POD IP CONTAINER(S) IMAGE(S) HOST LABELS STATUS CREATED MESSAGE
liveness-exec 10.244.3.7 kubernetes-minion-f08h/130.211.122.180 test=liveness Running 34 seconds
liveness gcr.io/google_containers/busybox Running 3 seconds last termination: exit code 137
liveness-http 10.244.0.8 kubernetes-minion-0bks/104.197.10.10 test=liveness Running 34 seconds
liveness gcr.io/google_containers/liveness Running 13 seconds last termination: exit code 2
```
The termination messages indicate that the liveness probes have failed, and the containers have been killed and recreated.
You can also see the container restart count being incremented by running `kubectl describe`.
```
# cluster/kubectl.sh describe pods liveness-exec | grep "Restart Count"
Restart Count: 8
```
You would also see the killing and creating events at the bottom of the *kubectl describe* output:
```
Thu, 14 May 2015 15:23:25 -0700 Thu, 14 May 2015 15:23:25 -0700 1 {kubelet kubernetes-minion-0uzf} spec.containers{liveness} killing Killing 88c8b717d8b0940d52743c086b43c3fad0d725a36300b9b5f0ad3a1c8cef2d3e
Thu, 14 May 2015 15:23:25 -0700 Thu, 14 May 2015 15:23:25 -0700 1 {kubelet kubernetes-minion-0uzf} spec.containers{liveness} created Created with docker id b254a9810073f9ee9075bb38ac29a4b063647176ad9eabd9184078ca98a60062
Thu, 14 May 2015 15:23:25 -0700 Thu, 14 May 2015 15:23:25 -0700 1 {kubelet kubernetes-minion-0uzf} spec.containers{liveness} started Started with docker id b254a9810073f9ee9075bb38ac29a4b063647176ad9eabd9184078ca98a60062
...
```

33
examples/liveness/exec-liveness.yaml
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@@ -1,22 +1,21 @@
apiVersion: v1beta1
desiredState:
manifest:
apiVersion: v1beta3
kind: Pod
metadata:
labels:
test: liveness
name: liveness-exec
spec:
containers:
- image: gcr.io/google_containers/busybox
name: liveness
- args:
- /bin/sh
- -c
- echo ok > /tmp/health; sleep 10; rm -rf /tmp/health; sleep 600
image: gcr.io/google_containers/busybox
livenessProbe:
exec:
command:
- "cat"
- "/tmp/health"
- cat
- /tmp/health
initialDelaySeconds: 15
command:
- "/bin/sh"
- "-c"
- "echo ok > /tmp/health; sleep 10; echo fail > /tmp/health; sleep 600"
id: liveness-exec
version: v1beta1
id: liveness-exec
kind: Pod
labels:
test: liveness
timeoutSeconds: 1
name: liveness

31
examples/liveness/http-liveness.yaml
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@@ -1,19 +1,18 @@
apiVersion: v1beta1
desiredState:
manifest:
containers:
- image: gcr.io/google_containers/liveness
name: liveness
livenessProbe:
httpGet:
path: "/healthz"
port: 8080
initialDelaySeconds: 15
command:
- /server
id: liveness-http
version: v1beta1
id: liveness-http
apiVersion: v1beta3
kind: Pod
metadata:
labels:
test: liveness
name: liveness-http
spec:
containers:
- args:
- /server
image: gcr.io/google_containers/liveness
livenessProbe:
httpGet:
path: /healthz
port: 8080
initialDelaySeconds: 15
timeoutSeconds: 1
name: liveness

29
examples/liveness/v1beta3/exec-liveness.yaml
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@@ -1,29 +0,0 @@
apiVersion: v1beta3
kind: ReplicationController
metadata:
labels:
test: liveness
name: liveness-exec
spec:
replicas: 1
selector:
test: liveness
template:
metadata:
labels:
test: liveness
spec:
containers:
- command:
- "/bin/sh"
- "-c"
- "echo ok > /tmp/health; sleep 10; echo fail > /tmp/health; sleep 600"
image: gcr.io/google_containers/busybox
livenessProbe:
exec:
command:
- "cat"
- "/tmp/health"
initialDelaySeconds: 15
name: liveness

26
examples/liveness/v1beta3/http-liveness.yaml
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@@ -1,26 +0,0 @@
apiVersion: v1beta3
kind: ReplicationController
metadata:
labels:
test: liveness
name: liveness-http
spec:
replicas: 1
selector:
test: liveness
template:
metadata:
labels:
test: liveness
spec:
containers:
- command:
- "/server"
image: gcr.io/google_containers/liveness
livenessProbe:
httpGet:
path: "/healthz"
port: 8080
initialDelaySeconds: 15
name: liveness