stacker.news/capture/index.js

117 lines
3.6 KiB
JavaScript

import express from 'express'
import puppeteer from 'puppeteer'
const captureUrl = process.env.CAPTURE_URL || 'http://host.docker.internal:3000/'
const port = process.env.PORT || 5678
const maxPages = Number(process.env.MAX_PAGES) || 5
const timeout = Number(process.env.TIMEOUT) || 10000
const cache = process.env.CACHE || 60000
const width = process.env.WIDTH || 600
const height = process.env.HEIGHT || 315
const deviceScaleFactor = process.env.SCALE_FACTOR || 2
// from https://www.bannerbear.com/blog/ways-to-speed-up-puppeteer-screenshots/
const args = [
'--autoplay-policy=user-gesture-required',
'--disable-background-networking',
'--disable-background-timer-throttling',
'--disable-backgrounding-occluded-windows',
'--disable-breakpad',
'--disable-client-side-phishing-detection',
'--disable-component-update',
'--disable-default-apps',
'--disable-dev-shm-usage',
'--disable-domain-reliability',
'--disable-extensions',
'--disable-features=AudioServiceOutOfProcess',
'--disable-hang-monitor',
'--disable-ipc-flooding-protection',
'--disable-notifications',
'--disable-offer-store-unmasked-wallet-cards',
'--disable-popup-blocking',
'--disable-print-preview',
'--disable-prompt-on-repost',
'--disable-renderer-backgrounding',
'--disable-setuid-sandbox',
'--disable-speech-api',
'--disable-sync',
'--hide-scrollbars',
'--ignore-gpu-blacklist',
'--metrics-recording-only',
'--mute-audio',
'--no-default-browser-check',
'--no-first-run',
'--no-pings',
'--no-sandbox',
'--no-zygote',
'--password-store=basic',
'--use-gl=swiftshader',
'--use-mock-keychain'
]
let browser
const app = express()
app.get('/health', (req, res) => {
res.status(200).end()
})
app.get('/*', async (req, res) => {
const url = new URL(req.originalUrl, captureUrl)
const timeLabel = `${Date.now()}-${url.href}`
const urlParams = new URLSearchParams(url.search)
const commentId = urlParams.get('commentId')
let page, pages
try {
console.time(timeLabel)
browser ||= await puppeteer.launch({
headless: 'new',
useDataDir: './data',
executablePath: 'google-chrome-stable',
args,
protocolTimeout: timeout,
defaultViewport: { width, height, deviceScaleFactor }
})
pages = (await browser.pages()).length
console.timeLog(timeLabel, 'capturing', 'current pages', pages)
// limit number of active pages
if (pages > maxPages + 1) {
console.timeLog(timeLabel, 'too many pages')
return res.writeHead(503, {
'Retry-After': 1
}).end()
}
page = await browser.newPage()
await page.emulateMediaFeatures([{ name: 'prefers-color-scheme', value: 'dark' }])
await page.goto(url.href, { waitUntil: 'load', timeout })
console.timeLog(timeLabel, 'page loaded')
if (commentId) {
console.timeLog(timeLabel, 'scrolling to comment')
await page.waitForSelector('.outline-it')
await new Promise((resolve, _reject) => setTimeout(resolve, 100))
}
const file = await page.screenshot({ type: 'png', captureBeyondViewport: false })
console.timeLog(timeLabel, 'screenshot complete')
res.setHeader('Content-Type', 'image/png')
res.setHeader('Cache-Control', `public, max-age=${cache}, immutable, stale-while-revalidate=${cache * 24}, stale-if-error=${cache * 24}`)
return res.status(200).end(file)
} catch (err) {
console.timeLog(timeLabel, 'error', err)
return res.status(500).end()
} finally {
console.timeEnd(timeLabel, 'pages at start', pages)
page?.close().catch(console.error)
}
})
app.listen(port, () =>
console.log(`Screenshot listen on http://:${port}`)
)