Add support for HTTP Basic auth based on ENV vars (#21)

* Support basic auth based on ENV vars

* Update README.

* Fix rubocop.

README.md

@@ -31,7 +31,8 @@ You can install ciao via the official Docker image `brotandgames/ciao` or using
 - `SECRET_KEY_BASE` will be auto-generated if you omit it
 - Check [SMTP Configuration](smtp_configuration.md) for all possible configuration variables, notes and example configurations for Gmail, Sendgrid etc.
 - By mounting a Docker volume you can avoid loosing data on restart or upgrade
-- Time zone is configurable per `TIME_ZONE` variable (default: UTC) eg. `TIME_ZONE="Vienna"` - you can find all possible values by executing `docker run --rm brotandgames/ciao rake time:zones`
+- Time zone is configurable per `TIME_ZONE` variable (default: UTC) eg. `TIME_ZONE="Vienna"` - you can find all possible values by executing `docker run --rm brotandgames/ciao rake time:zones` (since version 1.2.0)
+- You can enable HTTP Basic auth for ciao by defining `BASIC_AUTH_USERNAME` and `BASIC_AUTH_PASSWORD` eg. `BASIC_AUTH_USERNAME="ciao-admin"` `BASIC_AUTH_PASSWORD="********"` (since version 1.3.0)
 
 IMPORTANT: Be sure to enable authentication (eg. HTTP Basic auth) and TLS certificates if you serve ciao publicly.
 
@@ -225,7 +226,9 @@ dokku config:set --no-restart ciao \
   SMTP_AUTHENTICATION=plain \
   SMTP_ENABLE_STARTTLS_AUTO=auto \
   SMTP_USERNAME=ciao \
-  SMTP_PASSWORD="sensitive_password"
+  SMTP_PASSWORD="sensitive_password" \
+  BASIC_AUTH_USERNAME="username_for_basic_auth" \ # leave empty to disable basic auth
+  BASIC_AUTH_PASSWORD="password_for_basic_auth"
 ````
 
 Deploy ciao using your deployment method eg. [Dockerfile Deployment](http://dokku.viewdocs.io/dokku/deployment/methods/dockerfiles/), [Docker Image Deployment](http://dokku.viewdocs.io/dokku/deployment/methods/images/) etc.

app/controllers/application_controller.rb

@@ -1,5 +1,19 @@
 # frozen_string_literal: true
 
 class ApplicationController < ActionController::Base
+  before_action :authenticate
   protect_from_forgery unless: -> { request.format.json? }
+
+  def authenticate
+    # rubocop:disable Metrics/LineLength
+    basic_auth_username = ENV.fetch('BASIC_AUTH_USERNAME', '')
+    basic_auth_password = ENV.fetch('BASIC_AUTH_PASSWORD', '')
+
+    return true if basic_auth_username.empty?
+
+    authenticate_or_request_with_http_basic('Ciao Application') do |username, password|
+      username == basic_auth_username && password == basic_auth_password
+    end
+    # rubocop:enable Metrics/LineLength
+  end
 end