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Cloning docs for 0.19.0

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Brendan Burns
2015-06-10 09:23:42 -07:00
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release-0.19.0/examples/liveness/README.md Normal file
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## 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:
```
# kubectl create -f exec-liveness.yaml
# cluster/kbuectl.sh create -f http-liveness.yaml
```
Check the status of the pods once they are created:
```
# kubectl 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:
```
# kubectl 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`.
```
# kubectl 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
...
```
[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/examples/liveness/README.md?pixel)]()
[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/release-0.19.0/examples/liveness/README.md?pixel)]()

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release-0.19.0/examples/liveness/exec-liveness.yaml Normal file
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apiVersion: v1beta3
kind: Pod
metadata:
labels:
test: liveness
name: liveness-exec
spec:
containers:
- 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
initialDelaySeconds: 15
timeoutSeconds: 1
name: liveness

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release-0.19.0/examples/liveness/http-liveness.yaml Normal file
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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

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release-0.19.0/examples/liveness/image/Dockerfile Normal file
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FROM scratch
ADD server /server

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release-0.19.0/examples/liveness/image/Makefile Normal file
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all: push
server: server.go
CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -ldflags '-w' ./server.go
container: server
docker build -t gcr.io/google_containers/liveness .
push: container
gcloud preview docker push gcr.io/google_containers/liveness
clean:
rm -f server

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release-0.19.0/examples/liveness/image/server.go Normal file
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/*
Copyright 2014 The Kubernetes Authors All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// A simple server that is alive for 10 seconds, then reports unhealthy for
// the rest of its (hopefully) short existence.
package main
import (
"fmt"
"log"
"net/http"
"time"
)
func main() {
started := time.Now()
http.HandleFunc("/started", func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(200)
data := (time.Now().Sub(started)).String()
w.Write([]byte(data))
})
http.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
duration := time.Now().Sub(started)
if duration.Seconds() > 10 {
w.WriteHeader(500)
w.Write([]byte(fmt.Sprintf("error: %v", duration.Seconds())))
} else {
w.WriteHeader(200)
w.Write([]byte("ok"))
}
})
log.Fatal(http.ListenAndServe(":8080", nil))
}