Perform some checks on some environment variables

Some environment variables are extremely important when deploying
Portus. This commit makes Portus raise an exception during
initialization process when there's something off about these
environment variables.

Fixes #580

Signed-off-by: Miquel Sabaté Solà <msabate@suse.com>

Gemfile

@@ -65,7 +65,7 @@ end
 gem "puma", "~> 3.10.0" if ENV["PORTUS_PUMA_DEPLOYMENT"] == "yes" || !packaging?
 
 # Configuration management
-gem "cconfig", "~> 1.1.0"
+gem "cconfig", "~> 1.2.0"
 
 # In order to create the Gemfile.lock required for packaging
 # meaning that it should contain only the production packages

Gemfile.lock

@@ -80,7 +80,7 @@ GEM
       rack (>= 1.0.0)
       rack-test (>= 0.5.4)
       xpath (~> 2.0)
-    cconfig (1.1.1)
+    cconfig (1.2.0)
       safe_yaml (~> 1.0.0, >= 1.0.0)
     choice (0.2.0)
     cliver (0.3.2)
@@ -465,7 +465,7 @@ DEPENDENCIES
   brakeman
   byebug
   capybara (~> 2.14.3)
-  cconfig (~> 1.1.0)
+  cconfig (~> 1.2.0)
   codeclimate-test-reporter
   crono
   database_cleaner

config/initializers/environment_check.rb

@@ -0,0 +1,28 @@
+# This file checks for important environment variables. Some of them have to be
+# set in order for Portus to work in certain scenarios (e.g. secret key base on
+# production), others are strong recommendations.
+
+# Checks that the secret value has been set either in `config/secrets.yml` or as
+# an environment variable. If this is not the case, then it raises an exception
+# with the proper message.
+def mandatory_secret!(env, value)
+  return unless value.blank?
+  return unless ENV["PORTUS_#{env}"].blank?
+
+  raise "Environment variable `PORTUS_#{env}` has not been set! This variable is " \
+        "mandatory in production because it's needed for the generation of secrets."
+end
+
+if Rails.env.production?
+  # Mandatory environment variables for production.
+  mandatory_secret!("SECRET_KEY_BASE", Rails.application.secrets.secret_key_base)
+  mandatory_secret!("KEY_PATH", Rails.application.secrets.encryption_private_key_path)
+  mandatory_secret!("PASSWORD", Rails.application.secrets.portus_password)
+
+  # Strongly recommended environment variables for production.
+  if ENV["PORTUS_MACHINE_FQDN_VALUE"].blank?
+    if APP_CONFIG["machine_fqdn"]["value"] == APP_CONFIG.default_of("machine_fqdn.value")
+      Rails.logger.warn "You have not changed the FQDN configuration. Are you sure about this?"
+    end
+  end
+end