es_proxy.js

'use strict'

const https = require('https')
const { Client } = require('@elastic/elasticsearch')

const { ES_ENDPOINT, PATTERN = /^es_log/i, PORT = 8080 } = process.env

const client = new Client({ node: ES_ENDPOINT })

const processLog = input => {
    const matchIndex = input.match(/index=/i)
    if (Array.isArray(matchIndex)) {
        const indexSlicePos = input.indexOf(matchIndex[0])
        const index = input
            .slice(indexSlicePos, input.indexOf(' ', indexSlicePos))
            .slice(matchIndex[0].length - 1)
        const body = input.slice(input.indexOf(index) + index.length)
        return { index, body }
    }
    return
}

const handleLog = async log => {
    if (log.test(PATTERN)) {
        const processed = processLog(log)
        if (processed) await client.index(processed)
    }
}

const server = https.createServer(({ method }, res) => {
    if (method === 'POST') {
        let body = '';
        req.on('data', chunk => body += chunk.toString())
        req.on('end', () =>  {
            handleLog(body)
            res.writeHead(200)
            res.end()
        })
    }
})

server.listen(PORT)