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https://github.com/juffalow/node-express-kubernetes-example
Simple NodeJS application to explain basic parts of Kubernetes.
https://github.com/juffalow/node-express-kubernetes-example
example-project express kubernetes nodejs typescript
Last synced: 1 day ago
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Simple NodeJS application to explain basic parts of Kubernetes.
- Host: GitHub
- URL: https://github.com/juffalow/node-express-kubernetes-example
- Owner: juffalow
- License: mit
- Created: 2021-09-20T20:04:56.000Z (about 3 years ago)
- Default Branch: master
- Last Pushed: 2023-06-10T18:19:01.000Z (over 1 year ago)
- Last Synced: 2024-10-30T10:22:22.607Z (11 days ago)
- Topics: example-project, express, kubernetes, nodejs, typescript
- Language: HTML
- Homepage: https://node-example.juffalow.com
- Size: 156 KB
- Stars: 13
- Watchers: 3
- Forks: 10
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Node Express Kubernetes Example
Simple NodeJS application to explain basic parts of Kubernetes.
* [Run simple Node.js application in Kubernetes cluster (DigitalOcean)](https://juffalow.com/blog/javascript/run-simple-node-application-in-kubernetes-cluster)
## Routes
The `/app-id` route returns random string generated on application start, so that user can see if he is connecting to different pods (containers).
```json
{"appId":"1.13.647"}
```
Another request should return a different number in the end.
```json
{"appId":"1.13.539"}
```
The `/evn/:name` route returns environment variable as a proof that the application has access to values passed from *Kubernetes Secret*. For example you can try `/env/secretParameter`.
```json
{"secretParameter":"DatabaseCredentials"}
```
## Test readiness probe
If starting of a *pod* can take some time, you can define a `readinessProbe`. This is also usable if the *pod* has some unfinished work and is not available to receive any other requests. The check in this case is set to http get, so if it returns http status code `200` kubernetes will include the *pod* and if it returns status code `500` it will exclude the *pod*.
You can test it by refreshing the page and checking the `appId` and then visit [http://<IP address>/ready/toggle](https://kubernetes.kontentino.dev/ready/toggle), which will toggle the readiness for 10 seconds. During this time one of the app ids should not occure again.
## Test liveness probe
If some fatal error occured or something else that actually blocked the whole process and the app is basically dead, the `livenessProbe` check detects it and restarts the *pod*. To see this in action, you need to check *pods*:
```shell
kubectl get pods
```
This will return:
```
NAME READY STATUS RESTARTS AGE
node-docker-kubernetes-deployment-78f7d56b4b-2sg69 1/1 Running 0 5m37s
node-docker-kubernetes-deployment-78f7d56b4b-d8n9h 1/1 Running 0 5m26s
```
If you visit [http://<IP address>/alive/toggle](https://kubernetes.kontentino.dev/alive/toggle) and refresh the app a few times, one of the ids should not occure for a while. And if you check the *pods* again, the `restarts` info in one of the *pods* should show you `1`:
```
NAME READY STATUS RESTARTS AGE
node-docker-kubernetes-deployment-78f7d56b4b-2sg69 1/1 Running 1 5m37s
node-docker-kubernetes-deployment-78f7d56b4b-d8n9h 1/1 Running 0 5m26s
```
## Test
```js
let number = 0;
const load = async () => {
return fetch('https://node-test.kontentinoservices.dev/app-id')
.then(response => response.json())
.then((data) => {
console.log(`${number} App ID: ${data.appId}`);
});
}
const sleep = async (ms) => {
return new Promise((resolve) => {
setTimeout(resolve, ms);
});
}
while (true) {
number++;
await load();
await sleep(1000);
}
```
## Links
* [Kubernetes Tutorial - Step by Step Introduction to Basic Concepts](https://auth0.com/blog/kubernetes-tutorial-step-by-step-introduction-to-basic-concepts/)
* [Use Images in Your Registry with Kubernetes](https://www.digitalocean.com/docs/images/container-registry/quickstart/#use-images-in-your-registry-with-kubernetes)
* [Docker best practices with Node.js](https://dev.to/nodepractices/docker-best-practices-with-node-js-4ln4)
* [Node.js Best Practices - Docker](https://github.com/goldbergyoni/nodebestpractices/tree/master/sections/docker)
## License
[MIT license](./LICENSE)