Add: Gauge for Redis version

src/cache.js

@@ -37,6 +37,16 @@ export const fileCacheSizeGauge = new Gauge({
   help: 'Number of entries in file cache'
 })
 
+export const versionCountGauge = new Gauge({
+  name: 'redis_version_count_gauge',
+  help: 'Number of cache versions stored in Redis',
+  async collect () {
+    const pattern = `${process.env.REDIS_PREFIX}:*:mergedMetadata`
+    const results = await redis.client.keys(pattern)
+    this.set(results.length)
+  }
+})
+
 export function set (key, value, timeout) {
   logger.debug(`[Cache] Set ${key}`)
   if (cache[key] === value) return

src/version.js

@@ -189,7 +189,7 @@ export async function updateVersionProcessor (pubClient) {
       await warmCache({ version: fetchedVersionInfo.version, fetchFiles: true })
       await redis.client.set(getRedisKey({ name: 'versionInfo' }), stringifiedVersionInfo)
       await cache.get(getRedisKey({ version: fetchedVersionInfo.version, name: 'mergedMetadata' }), async () => [await fetchMergedMetadata()])
-      versionUpdateGauge.setToCurrentTime({ version: fetchVersionInfo.version })
+      versionUpdateGauge.setToCurrentTime({ version: fetchedVersionInfo.version })
       logger.info('[Version] publish update to other nodes.')
       pubClient.publish(getRedisKey({ name: 'updateVersionInfo' }), stringifiedVersionInfo)
     } else {