add: ui-middleware will slowly warm it's caches after version updates

src/files.js

@@ -84,3 +84,21 @@ export function getFile ({ version, path }) {
     return fetchFileWithHeaders({ version, path })
   })
 }
+
+export async function warmCache ({ version }) {
+  const start = +new Date()
+  logger.info('[File] start warming up the cache')
+  const viteManifests = await getViteManifests({ version })
+
+  for (const key of Object.keys(viteManifests)) {
+    const path = `/${viteManifests[key].file}`
+    if (!path) continue
+    try {
+      await getFile({ version, path })
+    } catch (err) {
+      logger.info(`[File] could not prefetch file ${path}`)
+    }
+  }
+
+  logger.info(`[File] finished warming up the cache in ${Math.floor((+new Date() - start) / 1000)}s`)
+}

src/index.js

@@ -8,6 +8,7 @@ import { configMap } from './configMap.js'
 import * as redis from './redis.js'
 import lightshipCjs from 'lightship'
 import { createMetricsServer } from './metrics.js'
+import { warmCache } from './files.js'
 
 config()
 
@@ -26,6 +27,13 @@ app.addHook('onReady', () => {
   lightship.signalReady()
 })
 
+app.addHook('onReady', () => {
+  // don't block the onReady hook
+  getLatestVersion()
+    .then(version => warmCache({ version }))
+    .catch(err => logger.error(err))
+})
+
 // Binds and listens for connections on the specified host and port
 app.listen({ host: '::', port: Number(process.env.PORT) })
 

src/version.js

@@ -5,6 +5,7 @@ import * as cache from './cache.js'
 import * as redis from './redis.js'
 import { Gauge } from 'prom-client'
 import { getViteManifests } from './manifests.js'
+import { warmCache } from './files.js'
 
 let latestVersion
 
@@ -80,6 +81,7 @@ export function registerLatestVersionListener (client) {
     await configMap.load()
     versionUpdateGauge.setToCurrentTime({ version })
     cache.clear()
+    warmCache({ version }).catch(err => logger.error(err))
     latestVersion = version
   })
 }
@@ -121,6 +123,7 @@ export async function updateVersionProcessor () {
       // if redis is disabled, this will only be trigger by a setInterval and not from a redis event
       logger.info('[Version] Clear local cache due to version update.')
       cache.clear()
+      warmCache({ version: fetchedVersion }).catch(err => logger.error(err))
       latestVersion = fetchedVersion
     }
     return latestVersion