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  1. 3
      .gitignore
  2. 158
      .openshiftio/application.yaml
  3. 13
      .theia/launch.json
  4. 201
      LICENSE
  5. 16
      README.md
  6. 3
      go.mod
  7. 2
      go.sum
  8. 45
      main.go
  9. 102
      public/index.html

3
.gitignore

@ -0,0 +1,3 @@
golang-health-check
__debug_bin
bindata.go

158
.openshiftio/application.yaml

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apiVersion: v1
kind: Template
metadata:
name: launchpad-builder
annotations:
description: This template creates a Build Configuration using an S2I builder.
tags: instant-app
parameters:
- name: SUFFIX_NAME
description: The suffix name for the template objects
displayName: Suffix name
value: ''
- name: RELEASE_VERSION
description: The release version number of application
displayName: Release version
value: 1.0.0
- name: SOURCE_REPOSITORY_URL
description: The source URL for the application
displayName: Source URL
required: true
- name: SOURCE_REPOSITORY_REF
description: The branch name for the application
displayName: Source Branch
value: master
required: true
objects:
- apiVersion: image.openshift.io/v1
kind: ImageStream
metadata:
name: 'golang-health-check${SUFFIX_NAME}'
labels:
version: '${RELEASE_VERSION}'
app: golang-health-check
spec: {}
- apiVersion: v1
kind: BuildConfig
metadata:
name: 'golang-health-check-s2i${SUFFIX_NAME}'
labels:
app: golang-health-check
version: '${RELEASE_VERSION}'
spec:
output:
to:
kind: ImageStreamTag
name: 'golang-health-check${SUFFIX_NAME}:${RELEASE_VERSION}'
postCommit: {}
resources: {}
source:
git:
uri: '${SOURCE_REPOSITORY_URL}'
ref: '${SOURCE_REPOSITORY_REF}'
type: Git
strategy:
type: Source
sourceStrategy:
from:
kind: DockerImage
name: 'registry.fedoraproject.org/f29/golang'
incremental: true
status:
lastVersion: 0
- apiVersion: v1
kind: Service
spec:
ports:
- protocol: TCP
port: 8080
targetPort: 8080
type: ClusterIP
selector:
project: golang-health-check
provider: golang-starters
metadata:
name: 'golang-health-check${SUFFIX_NAME}'
labels:
app: golang-health-check
provider: golang-starters
expose: 'true'
project: golang-health-check
version: '${RELEASE_VERSION}'
- apiVersion: v1
kind: DeploymentConfig
metadata:
name: 'golang-health-check${SUFFIX_NAME}'
labels:
app: golang-health-check
provider: golang-starters
project: golang-health-check
version: '${RELEASE_VERSION}'
spec:
template:
spec:
containers:
- readinessProbe:
httpGet:
path: /api/health
port: 8080
scheme: HTTP
failureThreshold: 3
initialDelaySeconds: 10
periodSeconds: 5
successThreshold: 1
timeoutSeconds: 1
livenessProbe:
httpGet:
path: /api/health
port: 8080
scheme: HTTP
failureThreshold: 2
initialDelaySeconds: 60
periodSeconds: 3
successThreshold: 1
timeoutSeconds: 1
image: ''
name: golang-health-check
securityContext:
privileged: false
ports:
- containerPort: 8080
name: http
protocol: TCP
metadata:
labels:
app: golang-health-check
project: golang-health-check
provider: golang-starters
version: '${RELEASE_VERSION}'
replicas: 1
selector:
app: golang-health-check
project: golang-health-check
provider: golang-starters
triggers:
- type: ConfigChange
- type: ImageChange
imageChangeParams:
automatic: true
containerNames:
- golang-health-check
from:
kind: ImageStreamTag
name: 'golang-health-check${SUFFIX_NAME}:${RELEASE_VERSION}'
- apiVersion: v1
kind: Route
metadata:
labels:
app: golang-health-check
project: golang-health-check
provider: golang-starters
version: '${RELEASE_VERSION}'
name: 'golang-health-check${SUFFIX_NAME}'
spec:
port:
targetPort: 8080
to:
kind: Service
name: 'golang-health-check${SUFFIX_NAME}'

13
.theia/launch.json

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{
"version": "0.2.0",
"configurations": [
{
"name": "Debug current file",
"type": "go",
"request": "launch",
"mode": "auto",
"program": "${fileDirname}"
}
]
}

201
LICENSE

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Apache License
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16
README.md

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# Golang Health Check
A booster demonstrating health checks and recovery using the kubernetes/openshift
`liveliness` and `readiness` probes.
# How to run
The project uses openshift s2i to build docker image. Run the following command
to build the docker image
```s2i build . registry.fedoraproject.org/f29/golang golang-health-check```
To start the web service, run
```docker run -p 8080:8080 golang-health-check```
The web service should now be accessible on `http://localhost:8080`

3
go.mod

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module github.com/golang-starters/golang-health-check
require github.com/elazarl/go-bindata-assetfs v1.0.0

2
go.sum

@ -0,0 +1,2 @@
github.com/elazarl/go-bindata-assetfs v1.0.0 h1:G/bYguwHIzWq9ZoyUQqrjTmJbbYn3j3CKKpKinvZLFk=
github.com/elazarl/go-bindata-assetfs v1.0.0/go.mod h1:v+YaWX3bdea5J/mo8dSETolEo7R71Vk1u8bnjau5yw4=

45
main.go

@ -0,0 +1,45 @@
package main
import (
"fmt"
"log"
"net/http"
)
var isOnline = true
func main() {
http.HandleFunc("/api/greeting", greeting)
http.HandleFunc("/api/stop", stop)
http.HandleFunc("/api/health", health)
http.Handle("/", http.FileServer(assetFS()))
fmt.Println("Web server running on port 8080")
log.Fatal(http.ListenAndServe(":8080", nil))
}
func greeting(w http.ResponseWriter, r *http.Request) {
if isOnline {
message := "World"
if m := r.FormValue("name"); m != "" {
message = m
}
fmt.Fprintf(w, "Hello %s!", message)
return
}
w.WriteHeader(503)
w.Write([]byte("Not Online"))
}
func stop(w http.ResponseWriter, r *http.Request) {
isOnline = false
w.Write([]byte("Stopping HTTP Server"))
}
func health(w http.ResponseWriter, r *http.Request) {
if isOnline {
w.WriteHeader(200)
return
}
w.WriteHeader(500)
}

102
public/index.html

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<html>
<head>
<meta charset="utf-8">
<title>Health Check Mission - Golang</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
crossorigin="anonymous">
</head>
<body>
<div class="container">
<div>
<div class="sect1">
<h2 id="_health_check_booster">Health Check Booster</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Demonstrates how the Kubernetes/Openshift health checks work to determine if a container is still alive (the <em>liveness</em>
of the container) and ready to serve the traffic for the HTTP endpoints of the application (the <em>readiness</em>
of the container).</p>
</div>
<div class="paragraph">
<p>To demonstrate this behavior, the application configures a <code>/health</code> HTTP endpoint, which is
used
by Kubernetes/Openshift to issue HTTP requests. If the container is still alive—​which means the Health HTTP
endpoint
is able to reply—​the management platform will receive HTTP code 200 as a response, and no further action
is taken. After you click the
<code>Stop Service</code> button, the HTTP endpoint starts
returning a 500 response, and the platform then
restarts
the pod with the failed container. While the pod is down, the booster UI polls the service
periodically
until the pod is restarted. In the meantime, do <strong>not</strong> refresh the page because it will
not be served until the pod finishes restarting.</p>
</div>
<div class="sect2">
<h3 id="_using_the_greeting_service">Using the greeting service</h3>
</div>
</div>
</div>
<form class="form-inline">
<div class="form-group">
<label for="name">Name</label>
<input type="text" class="form-control" id="name" placeholder="World">
</div>
<button id="invoke" type="submit" class="btn btn-success">Invoke</button>
<button id="stop" type="submit" class="btn btn-danger">Stop Service</button>
</form>
<h3>Result:</h3>
<pre><code id="greeting-result">Invoke the service to see the result.</code></pre>
</div>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa"
crossorigin="anonymous"></script>
<script>
var stopTime;
var attempts;
function invokeService() {
var n = $("#name").val() || "World";
$.get("/api/greeting?name=" + n, function (res) {
$("#greeting-result").html(res);
});
}
function invokeServiceandRetryUponFailures() {
var n = $("#name").val() || "World";
$.get("/api/greeting?name=" + n, function (res) {
var rebirth = new Date();
var diff = (stopTime.getTime() - rebirth.getTime()) / 1000;
var abs = Math.abs(diff);
$("#greeting-result").html(res + " (the recovery took " + abs + " seconds)");
})
.fail(function () {
$("#greeting-result").html("[" + ++attempts + "] Service not available... Retrying in 2 seconds");
setTimeout(invokeServiceandRetryUponFailures, 2000);
});
}
$(document).ready(function () {
$("#invoke").click(function (e) {
invokeService();
e.preventDefault();
});
$("#stop").click(function (e) {
$.get("/api/stop", function (data) {
$("#greeting-result").html("The application has been stopped...");
stopTime = new Date();
attempts = 0;
setTimeout(invokeServiceandRetryUponFailures, 2000);
});
e.preventDefault();
});
});
</script>
</body>
</html>
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