api-express-exporter is a prometheus exporter that helps you track express api requests.
npm install api-express-exporterapi-express-exporter is a prometheus exporter that helps you track express api requests. Plug it in and start monitoring express api requests!
``js
const app = express();
...
// Before all routes
app.use(require("api-express-exporter")()); // That's it!
// Apply your routes
app.get('hello', (req, res) => {
res.json({ 'hello': 'world!'})
});
`
api-express-exporter has three goals:
1. Allow you to aggregate metrics by the actual pattern across nested routers.
| request path | maps to path |
|------------------------|-------------------------|
| /api/sub/2/more/3 | /api/sub/:id/more/:id2 |
| /api/sub/30/more/50/ | /api/sub/:id/more/:id2 |
| /api/error | /api/error |
| /api/users/1 | /api/users/:userId |
| /api/users/100 | /api/users/:userId |
| /api/users/badId | /api/users/:userId |
| /api/users/uuid | /api/users/:userId |
api-express-exporter will not guess or replace your route params.
It will map them to the original pattern.
It does this by extracting your actual routes with express-list-endpoints, and then create url-pattern for each route. When a request comes in, api-express-exporter will use the UrlPattern objects to retrieve the original route pattern.
This is essential for large applications, if you have tens of thousands of products in a database collection, you do not want separate time series for each product, you want to see them all show up under /api/products/:productId.
Losing the original path param names is also error-prone, some frameworks will map both /api/products/500 and /api/users/500 to /api/products/:id and /api/users/:id, making it hard to read at a glance. We want /api/users/:userId and /api/products/:productId
2. Zero configuration to start with. Use reasonable defaults.
2. Keep things simple. 100 lines total in one file. Easy to fork and update.
This is a Node.js module available through the
npm registry.
Before installing, download and install Node.js.
Node.js 0.10 or higher is required.
Installation is done using the
npm install command:
`bash`
$ npm install api-express-exporter
This package depends on express, prom-client, express-list-endpoints, express-prom-bundle, and url-pattern
| Option Name | Description |
|------------------|--------------|
| host | host string for the metrics server. Defaults to 127.0.0.1 |(path) => new UrlPattern(path, { segmentNameCharset: "a-zA-Z0-9_-" })
| port | port that metrics server listens on. Defaults to 9991 |
| urlPatternMaker | function to create the url pattern matcher, defaults to |
| normalizePath | boolean. Set this to false to use the original url instead of cleaned up ones. |
| createServer | boolean. Set this to false to not create the exporter server endpoint |
When program starts, you will see the following:
`text`
Metrics server listening on 127.0.0.1:9991
Assuming you have a couple of routes defined like this:
`$js
// maps to /api/sub/:id/more/:id2
app.use("/api/sub", require("./sub_module"));
app.get("/api", (req, res) => {
res.status(200).send("Api Works.");
});
app.get("/api/fast/", (req, res) => {
res.status(200).send("Fast response!");
});
app.get("/api/slow", (req, res) => {
setTimeout(() => {
res.status(200).send("Slow response...");
}, 1000);
});
app.get("/api/error", (req, res, next) => {
try {
throw new Error("Something broke...");
} catch (error) {
res.status(500).send(error.message);
}
});
`
And you hit the corresponding routes in Postman or Curl. Check console again, you should see:
`$js`
$ node src/main.js
Server is running on port 4000
Metrics server listening on 127.0.0.1:9991
Route found: /api/sub/:id
Route found: /api/sub/:id/more/:id2
Route found: /api
Route found: /api/fast
Route found: /api/slow
Route found: /api/error
Route found: /api/list/:listId
Navigate to 127.0.0.1:9991/metrics, you will see:
`text
To see how to visualize the data in prometheus+grafana, you can check out Node.js Monitoring with Prometheus+Grafana
Happy monitoring!