Transfer files from k8s or docker shell to other host

If you are anytime stuck in a shell where you want to transfer files out of it, and do not have full access such as kubectl or docker exec. Here is the nifty hack:

Method 1 (Using ngrok):

Run a ngrok tunnel on the target computer

ngrok http 5000

Run a simple node program to capture request body

const express = require('express')
const app = express()
const port = 80
var bodyParser = require('body-parser')

app.post('/', (req, res)=> {
    console.log(req.body);
})

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`)
})

The disadvantage of this method is that post body size will be limited by terms dictated by ngrok

Another disadvantage is that you cannot use this to transfer sensitive info.

Method 2 (using Netcat)

Run the netcat server on the target computer

nc -l -p 5000  > file.txt < /dev/null 

Stream the file to the port from the source shell

cat anyfile.txt | netcat server.ip.here 5000

Here the target computer needs to be on internet. It can done via ngrok tcp tunnel or a small EC2 instance.