Add Redis gem and Create RedisClient (#4582)

* Add redis gem and client

* use keyword arguments in redis initializer

* check for REDISCLOUD_URL and fallback on REDIS_URL when connecting to redis

* dont parse Redis url in initializer

Envfile

@@ -27,6 +27,9 @@ variable :RACK_TIMEOUT_SERVICE_TIMEOUT, :Integer, default: 100_000
 # Production related config that can be ignored
 variable :DEPLOYMENT_SIGNATURE, :String, default: "Optional"
 
+# For Redis storage
+variable :REDIS_URL, :String, default: "redis://localhost:6379"
+
 ################################################
 ############## 3rd Party Services ##############
 ################################################

Gemfile

@@ -73,6 +73,7 @@ gem "rails-assets-airbrake-js-client", "~> 1.6", source: "https://rails-assets.o
 gem "rails-observers", "~> 0.1" # Rails observer (removed from core in Rails 4.0)
 gem "recaptcha", "~> 5.2", require: "recaptcha/rails" # Helpers for the reCAPTCHA API
 gem "redcarpet", "~> 3.5" # A fast, safe and extensible Markdown to (X)HTML parser
+gem "redis", "~> 4.1.3" # Redis ruby client
 gem "reverse_markdown", "~> 1.3" # Map simple html back into markdown
 gem "rolify", "~> 5.2" # Very simple Roles library
 gem "rouge", "~> 3.12" # A pure-ruby code highlighter

Gemfile.lock

@@ -613,6 +613,7 @@ GEM
     recaptcha (5.2.1)
       json
     redcarpet (3.5.0)
+    redis (4.1.3)
     regexp_parser (1.6.0)
     representable (3.0.4)
       declarative (< 0.1.0)
@@ -949,6 +950,7 @@ DEPENDENCIES
   rails-observers (~> 0.1)
   recaptcha (~> 5.2)
   redcarpet (~> 3.5)
+  redis (~> 4.1.3)
   reverse_markdown (~> 1.3)
   rolify (~> 5.2)
   rouge (~> 3.12)

config/initializers/redis.rb

@@ -0,0 +1,5 @@
+# DEV uses the RedisCloud Heroku Add-On which comes with the predefined env variable REDISCLOUD_URL
+redis_url = ENV["REDISCLOUD_URL"]
+redis_url ||= ApplicationConfig["REDIS_URL"]
+
+RedisClient = Redis.new(url: redis_url)

docs/installation/linux.md

@@ -31,6 +31,13 @@ DEV uses [ImageMagick](https://imagemagick.org/) to manipulate images on upload.
 
 Please refer to ImageMagick's [instructions](https://imagemagick.org/script/download.php) on how to install it.
 
+### Redis
+
+DEV requires Redis version 4.0 or higher.
+
+We recommend following Digital Ocean's extensive [How To Install and Configure Redis on Ubuntu 16.04](https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-redis-on-ubuntu-16-04)
+(available for other Linux distributions as well) to setup Redis.
+
 ## Installing DEV
 
 1. Fork DEV's repository, e.g. <https://github.com/thepracticaldev/dev.to/fork>

docs/installation/mac.md

@@ -27,6 +27,28 @@ DEV uses [ImageMagick](https://imagemagick.org/) to manipulate images on upload.
 
 You can install ImageMagick with `brew install imagemagick`.
 
+### Redis
+
+DEV requires Redis version 4.0 or higher.
+
+We recommend using [Homebrew](https://brew.sh):
+
+```shell
+brew install redis
+```
+
+you can follow the post installation instructions, we recommend using `brew services` to start Redis in the background:
+
+```shell
+brew services start redis
+```
+
+You can test if it's up and running by issuing the following command:
+
+```shell
+redis-cli ping
+```
+
 ## Installing DEV
 
 1. Fork DEV's repository, e.g. <https://github.com/thepracticaldev/dev.to/fork>

docs/installation/windows.md

@@ -105,6 +105,12 @@ DEV uses [ImageMagick](https://imagemagick.org/) to manipulate images on upload.
 
 Please refer to ImageMagick's [instructions](https://imagemagick.org/script/download.php) on how to install it.
 
+### Redis
+
+DEV requires Redis version 4.0 or higher.
+
+We recommend to follow [this guide](https://redislabs.com/blog/redis-on-windows-10/) to run Redis under WSL.
+
 ## Installing DEV
 
 1. Fork DEV's repository, eg. <https://github.com/thepracticaldev/dev.to/fork>

docs/technical-overview.md

@@ -8,6 +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
 - [_Fastly_](https://www.fastly.com/) for [edge caching](https://dev.to/ben/making-devto-insanely-fast)
 - [_Cloudinary_](https://cloudinary.com/) for image manipulation/serving
 - [_Airbrake_](https://airbrake.io/) for error monitoring