Question 98511 in Nginx Question posted in
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Best way to handle REST requests with external programs? – Nginx

TL;DR
How can I setup a light-weight web server to execute external programs to handle REST requests?

The long version:
We have a set of services and databases deployed in Kubernetes via Helm. There are some executables that perform maintenance, cleanup, backup, restore etc that I need to execute (some on-demand & some periodically).
I want to park a small, light-weight web server somewhere mounted with access to the binaries and execute them when REST requests are handled.

  • server needs to have a small memory footprint
  • traffic will be really light (like minutes between each request)
  • security is not super important (it will run inside our trusted zone)
  • server needs to handle GET and POST (i.e. passing binary content TO & FROM external program)

I’ve glanced at lighttpd or nginx with CGI modules but I’m not experienced with those.
What do you recommend? Do you have a small example to show how to do it?

Tags:

2

Answers


  1. 0

    Here’s k8s native approach:

    ... a set of services and databases deployed in Kubernetes... some executables that perform maintenance, cleanup, backup, restore etc...some on-demand & some periodically

    If you can bake those "executables" into an image, you can run these programs on-demand as k8s job, and schedule repeating job as k8s cronjob. If this is possible in your context then you can create a k8s role that has just enough right to call job/cronjob api, and bind this role to a dedicated k8s service account.

    Then you build a mini web application using any language/framework of your choice, run this web application on k8s using the dedicated service account, expose your pod as service using NodePort/LoadBalancer to receive GET/POST requests. Finally you make direct api call to k8s api-server to run jobs according to your logic.

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  2. 0

    I think I’d make a small service. I’d choose Node, since that’s something I’m familiar with, but lots of languages have adopted this way of setting up a server, so choose something you like.

    index.js

    const express = require('express')
const { exec } = require('child_process')
const app = express()
const port = 3000

app.get('/os-release', (req, res) => {
  exec('cat /etc/os-release', (error, stdout, stderr) => {
    res.send(stdout)
  })
})

app.listen(port, () => {
  console.log(`Listening on port ${port}`)
})

    package.json

    {
  "name": "shell-exec",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo "Error: no test specified" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "child_process": "^1.0.2",
    "express": "^4.17.1"
  }
}

    Dockerfile

    FROM node:alpine
EXPOSE 3000
WORKDIR /app
COPY package.json ./
RUN npm install
COPY . ./
CMD ["node", "index.js"]

    I should be relatively easy to make POST requests that take input parameters if you need to do that. I also like that you can send the output of the command back to the caller.

    If you build and run this, you can then hit the /os-release endpoint and get data back from the cat /etc/os-release command.

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