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https://github.com/r2d2bzh/moleculer-healthcheck-middleware
See https://gist.github.com/icebob/c717ae22002b9ecaa4b253a67952da3a
https://github.com/r2d2bzh/moleculer-healthcheck-middleware
Last synced: about 2 months ago
JSON representation
See https://gist.github.com/icebob/c717ae22002b9ecaa4b253a67952da3a
- Host: GitHub
- URL: https://github.com/r2d2bzh/moleculer-healthcheck-middleware
- Owner: r2d2bzh
- Created: 2020-05-27T07:10:27.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-06-16T12:25:44.000Z (7 months ago)
- Last Synced: 2024-11-10T02:34:09.243Z (2 months ago)
- Language: JavaScript
- Size: 352 KB
- Stars: 5
- Watchers: 3
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
- awesome-moleculer - Health-check middleware - Health-check middleware for Moleculer (for Kubernetes liveness readiness checks) (Middlewares / General)
README
# Health-check middleware for Moleculer
The following originally comes from a gist available here:
https://gist.github.com/icebob/c717ae22002b9ecaa4b253a67952da3a
Most credits go to [@icebob](https://github.com/icebob).
This repository only provides us a way to publish, maintain and perhaps customize this middleware.
This module is available on the public NPM registry:
```sh
npm install @r2d2bzh/moleculer-healthcheck-middleware
```
Use it for Kubernetes liveness & readiness checks.
The middleware opens a HTTP server on port 3001.
To check, open the http://localhost:3001/live & http://localhost:3001/ready URLs.
## Response
```js
{
"state": "up",
"uptime": 7.419,
"timestamp": 1562790370161
}
```
> The `state` can be `"starting"` (503), `"up"` (200), `"stopping"` (503) or `"down"` (503).
## Usage
**Load with default options**
```js
// moleculer.config.js
const HealthMiddleware = require('@r2d2bzh/moleculer-healthcheck-middleware');
module.exports = {
middlewares: [
HealthMiddleware()
]
};
```
**Load with custom options**
```js
// moleculer.config.js
const HealthMiddleware = require('@r2d2bzh/moleculer-healthcheck-middleware');
module.exports = {
middlewares: [
HealthMiddleware({
port: 3333,
readiness: {
path: "/ready"
},
liveness: {
path: "/live"
}
})
]
};
```
In order to check liveness and/or readiness a little deeper, you can also give the module your own *checker function* which takes a callback.
If you give a parameter to the `next` callback you will tell the middlware to fail the liveness and/or readiness check.
Also if you do not respond in a certain amount of time, the liveness and/or readiness check will fail.
```js
// moleculer.config.js
const HealthMiddleware = require('@r2d2bzh/moleculer-healthcheck-middleware');
module.exports = {
middlewares: [
HealthMiddleware({
liveness: {
checkerTimeoutMs: 20000, // default value
checker: function(next) {
// Execute here your liveness check...
if (ok) {
next();
} else {
next('error');
}
},
},
}),
],
};
```
The checker can also be initialized through a *createChecker* factory which takes the broker as a parameter.
Provide your own implementation of *createChecker* to the healthcheck middleware if you need the checker function to have access to the broker.
It will be called during the *started* Moleculer middleware hook.
```js
const HealthMiddleware = require('@r2d2bzh/moleculer-healthcheck-middleware');
module.exports = {
middlewares: [
HealthMiddleware({
liveness: {
createChecker: (broker) =>
(next) => {
if (ok) {
broker.getLogger('healthcheck').info('Everything is fine.');
next();
} else {
broker.getLogger('healthcheck').error('error');
next('error');
}
}
}
}),
],
};
```
### Usage in Kubernetes
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: greeter
spec:
selector:
matchLabels:
app: greeter
replicas: 1
template:
metadata:
labels:
app: greeter
spec:
containers:
- name: greeter
image: moleculer/demo:1.4.2
livenessProbe:
httpGet:
path: /live
port: 3001
readinessProbe:
httpGet:
path: /ready
port: 3001
```