Migrating from App Engine Memcache to Cloud Memorystore (Module 13)

Posted by Wesley Chun (@wescpy), Developer Advocate, Google Cloud

Introduction and history

The preceding Module 12 episode of the Serverless Migration Station online video sequence demonstrated how to add App Engine Memcache use to an existing app that has transitioned from the webapp2 framework to Flask. Today’s Module 13 episode proceeds its modernization by demonstrating how to migrate that application from Memcache to Cloud Memorystore. Transferring from legacy APIs to standalone Cloud companies tends to make apps more moveable and supplies an less complicated changeover from Python 2 to 3. It also makes it attainable to change to other Cloud compute platforms must that be wanted or advantageous. Developers gain from upgrading to present day language releases and acquire additional flexibility in application-hosting options.

While Application Engine Memcache supplies a fundamental, reduced-overhead, serverless caching service, Cloud Memorystore “usually takes it to the upcoming level” as a standalone item. Instead than a proprietary caching engine, Cloud Memorystore gives consumers the choice to pick from a pair of open supply engines, Memcached or Redis, just about every of which supplies more characteristics unavailable from App Engine Memcache. Cloud Memorystore is generally more charge productive at-scale, delivers superior availability, delivers computerized backups, etcetera. On major of this, a single Memorystore instance can be applied across lots of purposes as well as incorporates improvements to memory handling, configuration tuning, and so on., received from expertise running a large fleet of Redis and Memcached occasions.

Although Memcached is additional comparable to Memcache in usage/options, Redis has a significantly richer established of info constructions that permit strong application features if used. Redis has also been recognized as the most loved databases by developers in StackOverflow’s annual builders survey, and it’s a excellent ability to select up. For these causes, we selected Redis as the caching engine for our sample app. Having said that, if your apps’ use of App Motor Memcache is further or more elaborate, a migration to Cloud Memorystore for Memcached might be a greater selection as a nearer analog to Memcache. out?v=lyqSTsLYBOU

Migrating to Cloud Memorystore for Redis highlighted movie


Accomplishing the migration

The sample application registers unique world wide web web site “visits,” storing customer details this kind of as IP tackle and consumer agent. In the authentic application, the most the latest visits are cached into Memcache for an hour and used for display screen if the very same user continually refreshes their browser for the duration of this interval caching is a a person way to counter this abuse. New website visitors or cache expiration success new visits as well as updating the cache with the most current visits. This sort of operation have to be preserved when migrating to Cloud Memorystore for Redis.

Underneath is pseudocode representing the main element of the app that saves new visits and queries for the most latest visits. Before, you can see how the most modern visits are cached into Memcache. Soon after finishing the migration, the fundamental caching infrastructure has been swapped out in favor of Memorystore (by using language-distinct Redis shopper libraries). In this migration, we selected Redis version 5., and we suggest the latest variations, 5. and 6.x at the time of this creating, as the newest releases function added general performance rewards, fixes to strengthen availability, and so on. In the code snippets underneath, see how the phone calls among both caching programs are virtually identical. The bolded lines signify the migration-affected code managing the cached info.

Switching from App Motor Memcache to Cloud Memorystore for Redis


The migration coated starts with the Module 12 sample application (“Start”). Migrating the caching technique to Cloud Memorystore and other requisite updates final results in the Module 13 sample app (“Complete”) along with an optional port to Python 3. To practice this migration on your own to support put together for your personal migrations, observe the codelab to do it by-hand although next together in the online video.

When the code migration demonstrated seems simple, the most significant modify is that Cloud Memorystore calls for dedicated server cases. For this reason, a Serverless VPC connector is also wanted to link your Application Motor app to people Memorystore occasions, necessitating extra devoted servers. On top of that, neither Cloud Memorystore nor Cloud VPC are cost-free solutions, and neither has an “Normally free” tier quota. Just before relocating ahead this migration, check out the pricing documentation for Cloud Memorystore for Redis and Serverless VPC access to figure out cost issues in advance of creating a motivation.

A single critical progress that may perhaps have an affect on your determination: In Fall 2021, the Application Engine crew prolonged assist of numerous of the legacy bundled services like Memcache to next-era runtimes, which means you are no lengthier required to migrate to Cloud Memorystore when porting your application to Python 3. You can keep on using Memcache even when upgrading to 3.x so very long as you retrofit your code to access bundled companies from subsequent-generation runtimes.

A go to Cloud Memorystore and present day migration approaches will be in this article if and when you decide this is the way you want to acquire for your App Engine apps. All Serverless Migration Station content material (codelabs, video clips, resource code [when available]) can be accessed at its open supply repo. While our content material at first focuses on Python end users, we approach to protect other language runtimes, so continue to be tuned. For further movie material, examine out our broader Serverless Expeditions series.

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