Remove memcache dalli gem and setup code (#5057) [deploy]

Envfile

@@ -202,12 +202,6 @@ group :production do
   variable :SEND_LOGS_TO_TIMBER, :String  # Defaults to true in production, false in development
   variable :TIMBER, :String  # Only required if above is "true" or unset
 
-  # Memcachier
-  # (https://www.memcachier.com/documentation/rails)
-  variable :MEMCACHIER_SERVERS, :String
-  variable :MEMCACHIER_USERNAME, :String
-  variable :MEMCACHIER_PASSWORD, :String
-
   # Sendgrid
   # (https://sendgrid.com/docs/API_Reference/api_v3.html)
   variable :SENDGRID_USERNAME_ACCEL, :String

Gemfile

@@ -27,7 +27,6 @@ gem "carrierwave-bombshelter", "~> 0.2" # Protect your carrierwave from image bo
 gem "cld", "~> 0.8" # Compact Language Detection for Ruby
 gem "cloudinary", "~> 1.13" # Client library for easily using the Cloudinary service
 gem "counter_culture", "~> 2.2" # counter_culture provides turbo-charged counter caches that are kept up-to-date
-gem "dalli", "~> 2.7" # High performance memcached client for Ruby
 gem "delayed_job_active_record", "~> 4.1" # ActiveRecord backend for Delayed::Job
 gem "delayed_job_web", "~> 1.4" # Web interface for delayed_job
 gem "devise", "~> 4.7" # Flexible authentication solution for Rails

Gemfile.lock

@@ -212,7 +212,6 @@ GEM
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.5)
-    dalli (2.7.10)
     dante (0.2.0)
     datetime_picker_rails (0.0.7)
       momentjs-rails (>= 2.8.1)
@@ -883,7 +882,6 @@ DEPENDENCIES
   cld (~> 0.8)
   cloudinary (~> 1.13)
   counter_culture (~> 2.2)
-  dalli (~> 2.7)
   delayed_job_active_record (~> 4.1)
   delayed_job_web (~> 1.4)
   derailed_benchmarks (~> 1.4)

app/views/notifications/_article.html.erb

@@ -32,10 +32,6 @@
       <% end %>
     <% end %>
 
-    <%# keeping this section of out the cache: if the article is never updated
-        the containing cache will likely never expire and this section will be
-        fixed in time until expired randomly by Memcache's algorithm, which can
-        be too late for the freshness of the user experience %>
     <div>
       <% if json_data["article"]["published_at"] %>
         <small><%= time_ago_in_words json_data["article"]["published_at"] %> ago</small>

config/environments/production.rb

@@ -99,19 +99,8 @@ Rails.application.configure do
   # Do not dump schema after migrations.
   config.active_record.dump_schema_after_migration = false
 
-  # TODO: Remove after cache store flip
-  if ENV["USE_REDIS"]
-    DEFAULT_EXPIRATION = 24.hours.to_i.freeze
-    config.cache_store = :redis_store, ENV["REDIS_URL"], { expires_in: DEFAULT_EXPIRATION }
-  else
-    config.cache_store = :dalli_store,
-                         (ENV["MEMCACHIER_SERVERS"] || "").split(","),
-                         { username: ENV["MEMCACHIER_USERNAME"],
-                           password: ENV["MEMCACHIER_PASSWORD"],
-                           failover: true,
-                           socket_timeout: 1.5,
-                           socket_failure_delay: 0.2 }
-  end
+  DEFAULT_EXPIRATION = 24.hours.to_i.freeze
+  config.cache_store = :redis_store, ENV["REDIS_URL"], { expires_in: DEFAULT_EXPIRATION }
 
   config.app_domain = ENV["APP_DOMAIN"]
 

config/initializers/new_framework_defaults_5_2.rb

@@ -6,11 +6,6 @@
 #
 # Read the Guide for Upgrading Ruby on Rails for more info on each option.
 
-# NOTE: we can't enable this just yet because it likely requires a flushing on the whole cache
-# due to how the new cache keys are generated. This is intended to improve and optimize caching
-# strategies by Rails but since we use "dalli_store" we can't enable this without flushing the cache.
-# This won't be a problem when we'll have switched to "redis_cache_store"
-# see <https://blog.heroku.com/cache-invalidation-rails-5-2-dalli-store>
 # Make Active Record use stable #cache_key alongside new #cache_version method.
 # This is needed for recyclable cache keys.
 # Rails.application.config.active_record.cache_versioning = true

docs/technical-overview/stack.md

@@ -8,8 +8,7 @@ For the Dev.to tech stack we use:
 
 - [_Puma_](https://github.com/puma/puma) as the web server
 - [_PostgreSQL_](https://www.postgresql.org/) as the primary database
-- [_Redis_](https://redis.io/) to store additional data and eventually replace
-  memcache
+- [_Redis_](https://redis.io/) to store cached data
 - [_Fastly_](https://www.fastly.com/) for
   [edge caching](https://dev.to/ben/making-devto-insanely-fast)
 - [_Cloudinary_](https://cloudinary.com/) for image manipulation/serving