How to get the local domain ip address by using koaJS

Obtaining the local network IP address in KoaJS primarily relies on information within the request object ctx.request. The Koa framework does not directly provide a specific method to obtain the local network IP address, but we can achieve this through indirect methods.

Here is a basic example of obtaining the local network IP address in the KoaJS environment:

javascript
const Koa = require('koa');
const app = new Koa();

app.use(async ctx => {
  // Obtain IP address
  const ip = ctx.request.ip;

  // Output IP address
  ctx.body = `Your IP address is ${ip}`;
});

app.listen(3000, () => {
  console.log('Server is running on http://localhost:3000');
});

In this example, we use the ctx.request.ip property. This property is typically used to obtain the client's IP address. However, this address may represent the IP address after reverse proxying. If your application is deployed in environments with reverse proxies (e.g., Nginx), you may need to retrieve the original IP address from the X-Forwarded-For HTTP header.

Here is an example of how to obtain the IP address from the X-Forwarded-For header:

javascript
app.use(async ctx => {
  // Obtain the value of the X-Forwarded-For header
  const xForwardedFor = ctx.request.get('X-Forwarded-For');
  let ip;
  if (xForwardedFor) {
    ip = xForwardedFor.split(',')[0]; // May contain multiple IP addresses, so we take the first one
  } else {
    ip = ctx.request.ip;
  }

  // Output IP address
  ctx.body = `Your IP address is ${ip}`;
});

The above code first checks for the existence of the X-Forwarded-For header. If it exists, it parses the IP address from it; otherwise, it directly uses ctx.request.ip to obtain the IP address.

This is a basic method for obtaining the IP address. Depending on your specific requirements and deployment environment, adjustments may be necessary.