Use node-redis for page cache (#18421)

* Use [node-]redis as a direct dependency

* Extract Redis client creation to its own module

* Attach extensive logging in the Redis client creation module

* Allow the rate limiter to pass requests when Redis is disconnected

* Update rate-limit-redis

* Default error input to empty object for formatRedisError method

* Provide a name for the rate limiter's Redis client

* Include redis-mock, exclude ioredis/ioredis-mock

* Remove unused RedisAccessor#exists method

* Switch RedisAccessor to use redis/redis-mock

* Provide a name for logging on the Redis page cache

* Remove extraneous trailing space from Redis logging prefix

Our updated use of console.* will already be adding a space after the prefix

* Replace ioredis-mock with redis-mock in tests

* Revert removal of ioredis dependency

* Bind Redis client to async promisified methods

* Extract former RedisAccessor constructor tests to new create-client tests

* Update RedisAccessor tests to work with the callback-based redis client

* Handle formatting Redis errors (or not) with more resiliency

Author: JamesMGreene

lib/redis-accessor.js

@@ -1,42 +1,21 @@
-const Redis = require('ioredis')
-const InMemoryRedis = require('ioredis-mock')
+const createRedisClient = require('./redis/create-client')
+const InMemoryRedis = require('redis-mock')
+const { promisify } = require('util')
 
-const { CI, NODE_ENV, REDIS_URL, REDIS_MAX_DB } = process.env
+const { CI, NODE_ENV, REDIS_URL } = process.env
 
 // Do not use real a Redis client for CI, tests, or if the REDIS_URL is not provided
 const useRealRedis = !CI && NODE_ENV !== 'test' && !!REDIS_URL
 
-// By default, every Redis instance supports database numbers 0 - 15
-const redisMaxDb = REDIS_MAX_DB || 15
-
-// Enable better stack traces in non-production environments
-const redisBaseOptions = {
-  showFriendlyErrorStack: NODE_ENV !== 'production'
-}
-
 class RedisAccessor {
-  constructor ({ databaseNumber = 0, prefix = null, allowSetFailures = false } = {}) {
-    if (!Number.isInteger(databaseNumber) || databaseNumber < 0 || databaseNumber > redisMaxDb) {
-      throw new TypeError(
-        `Redis database number must be an integer between 0 and ${redisMaxDb} but was: ${JSON.stringify(databaseNumber)}`
-      )
-    }
-
+  constructor ({ databaseNumber = 0, prefix = null, allowSetFailures = false, name = null } = {}) {
     const redisClient = useRealRedis
-      ? new Redis(REDIS_URL, {
-          ...redisBaseOptions,
+      ? createRedisClient({
+          url: REDIS_URL,
           db: databaseNumber,
-
-          // Only add this configuration for TLS-enabled REDIS_URL values.
-          // Otherwise, it breaks for local Redis instances without TLS enabled.
-          ...REDIS_URL.startsWith('rediss://') && {
-            tls: {
-              // Required for production Heroku Redis
-              rejectUnauthorized: false
-            }
-          }
+          name: name || 'redis-accessor'
         })
-      : new InMemoryRedis()
+      : InMemoryRedis.createClient()
 
     this._client = redisClient
 
@@ -96,6 +75,7 @@ class RedisAccessor {
   }
 
   async set (key, value, options = {}) {
+    const setAsync = promisify(this._client.set).bind(this._client)
     const fullKey = this.prefix(key)
 
     if (typeof value !== 'string' || !value) {
@@ -106,7 +86,7 @@ class RedisAccessor {
     const setArgs = this.constructor.translateSetArguments(options)
 
     try {
-      const result = await this._client.set(fullKey, value, ...setArgs)
+      const result = await setAsync(fullKey, value, ...setArgs)
       return result === 'OK'
     } catch (err) {
       const errorText = `Failed to set value in Redis.
@@ -124,14 +104,10 @@ Error: ${err.message}`
   }
 
   async get (key) {
-    const value = await this._client.get(this.prefix(key))
+    const getAsync = promisify(this._client.get).bind(this._client)
+    const value = await getAsync(this.prefix(key))
     return value
   }
-
-  async exists (key) {
-    const result = await this._client.exists(this.prefix(key))
-    return result === 1
-  }
 }
 
 module.exports = RedisAccessor

lib/redis/create-client.js

@@ -6,10 +6,12 @@ const { REDIS_MIN_DB, REDIS_MAX_DB } = process.env
 const redisMinDb = REDIS_MIN_DB || 0
 const redisMaxDb = REDIS_MAX_DB || 15
 
-function formatRedisError (error = {}) {
-  const { code } = error
-  const preamble = error.constructor.name + (code ? ` with code "${code}"` : '')
-  return preamble + error.toString()
+function formatRedisError (error) {
+  const errorCode = error ? error.code : null
+  const errorName = error ? error.constructor.name : 'Error'
+  const errorMsg = error ? error.toString() : 'unknown error'
+  const preamble = errorName + (errorCode ? ` with code "${errorCode}"` : '')
+  return preamble + ': ' + errorMsg
 }
 
 module.exports = function createClient (options = {}) {
@@ -45,7 +47,7 @@ module.exports = function createClient (options = {}) {
   })
 
   // If a `name` was provided, use it in the prefix for logging event messages
-  const logPrefix = '[redis' + (name ? ` (${name})` : '') + '] '
+  const logPrefix = '[redis' + (name ? ` (${name})` : '') + ']'
 
   // Add event listeners for basic logging
   client.on('connect', () => { console.log(logPrefix, 'Connection opened') })

middleware/render-page.js

@@ -16,7 +16,8 @@ const pageCache = new RedisAccessor({
   databaseNumber: pageCacheDatabaseNumber,
   prefix: (HEROKU_RELEASE_VERSION ? HEROKU_RELEASE_VERSION + ':' : '') + 'rp',
   // Allow for graceful failures if a Redis SET operation fails
-  allowSetFailures: true
+  allowSetFailures: true,
+  name: 'page-cache'
 })
 
 // a list of query params that *do* alter the rendered page, and therefore should be cached separately

package-lock.json

@@ -58,8 +58,7 @@
     "hot-shots": "^8.2.0",
     "html-entities": "^1.2.1",
     "imurmurhash": "^0.1.4",
-    "ioredis": "^4.19.4",
-    "ioredis-mock": "^5.2.0",
+    "ioredis": "^4.24.4",
     "is-url": "^1.2.4",
     "js-cookie": "^2.2.1",
     "js-yaml": "^3.14.0",
@@ -79,6 +78,7 @@
     "react": "^17.0.1",
     "react-dom": "^17.0.1",
     "redis": "^3.0.2",
+    "redis-mock": "^0.56.3",
     "rehype-autolink-headings": "^2.0.5",
     "rehype-highlight": "^3.1.0",
     "rehype-raw": "^4.0.2",