// // This middleware function is intended to be used for testing caching behavior with Fastly. // It will intercept ALL URLs that are routed to it and respond with a simple HTML body // containing a timestamp. // The logic will detect certain values in the path and set the HTTP status and/or the // Surrogate-Control header value. // // NOTE: This middleware is intended to be removed once testing is complete! // import express from 'express' import crypto from 'crypto' const router = express.Router() router.get('/*', function (req, res) { // If X-CacheTest-Error is set, simulate the site being down (regardless of URL) if (req.get('X-CacheTest-Error')) { res.status(parseInt(req.get('X-CacheTest-Error'))).end() return } const cacheControlModeParam = req.get('X-CacheTest-CCMode') ?? 'none' const staleIfErrorParam = req.get('X-CacheTest-StaleIfError') ?? '300' const staleWhileRevalidateParam = req.get('X-CacheTest-StaleWhileRevalidate') ?? '60' const maxAgeParam = req.get('X-CacheTest-MaxAge') ?? '300' const path = req.params[0] const content = `

Timestamp: ${new Date()}

` let status = 200 const surrogateControlValues = [] if (path.includes('max-age')) surrogateControlValues.push(`max-age=${maxAgeParam}`) if (path.includes('must-revalidate')) surrogateControlValues.push('must-revalidate') if (path.includes('no-cache')) surrogateControlValues.push('no-cache') if (path.includes('no-store')) surrogateControlValues.push('no-store') if (path.includes('private')) surrogateControlValues.push('private') if (path.includes('proxy-revalidate')) surrogateControlValues.push('proxy-revalidate') if (path.includes('public')) surrogateControlValues.push('public') if (path.includes('stale-if-error')) surrogateControlValues.push(`stale-if-error=${staleIfErrorParam}`) if (path.includes('stale-while-revalidate')) surrogateControlValues.push(`stale-while-revalidate=${staleWhileRevalidateParam}`) if (path.includes('no-cookies')) { res.removeHeader('Set-Cookie') } if (path.includes('etag')) { res.set({ ETag: `"${crypto.createHash('md5').update(content).digest('hex')}"`, }) } if (path.includes('error500')) { status = 500 } else if (path.includes('error502')) { status = 502 } else if (path.includes('error503')) { status = 503 } else if (path.includes('error504')) { status = 504 } if (surrogateControlValues.length > 0) { switch (cacheControlModeParam) { case 'none': res.set({ 'surrogate-control': surrogateControlValues.join(', '), }) break case 'both': res.set({ 'surrogate-control': surrogateControlValues.join(', '), 'cache-control': surrogateControlValues.join(', ').replace('max-age', 's-maxage'), }) break case 'only': res.set({ 'cache-control': surrogateControlValues.join(', ').replace('max-age', 's-maxage'), }) break } } res.status(status) res.send(content) res.end() }) export default router