[ENV] Signing key config

# Conflicts:
#	config/secrets.yml

app/services/signature_service.rb

@@ -1,6 +1,4 @@
 class SignatureService
-  CONFIG_PATH = Rails.root.join("config", "signing_key.yml")
-
   class << self
     def generate
       RbNaCl::Util.bin2hex(RbNaCl::SigningKey.generate)
@@ -24,15 +22,7 @@ class SignatureService
     private
 
     def signing_key
-      @@signing_key ||= RbNaCl::SigningKey.new(RbNaCl::Util.hex2bin(config[:key]))
-    end
-
-    def config
-      if File.exist?(CONFIG_PATH)
-        YAML.safe_load(File.read(CONFIG_PATH)).symbolize_keys
-      else
-        {}
-      end
+      @@signing_key ||= RbNaCl::SigningKey.new(RbNaCl::Util.hex2bin(Rails.application.secrets.signing_key))
     end
   end
 end

config/secrets.yml

@@ -11,6 +11,7 @@
 # if you're sharing your code publicly.
 defaults: &defaults
   secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
+  signing_key: <%= ENV["SIGNING_KEY"] %>
   basic_auth:
     username: <%= ENV['BASIC_AUTH_USERNAME'] %>
     password: <%= ENV['BASIC_AUTH_PASSWORD'] %>
@@ -46,10 +47,12 @@ defaults: &defaults
 development:
   <<: *defaults
   secret_key_base: 05a2d479d8e412198dabd08ef0eee9d6e180f5cbb48661a35fd1cae287f0a93d40b5f1da08f06780d698bbd458a0ea97f730f83ee780de5d4e31f649a0130cf0
+  signing_key: aef3153a9829fa4ba10acb02927ac855df6b92795b1ad265d654443c4b14a017
 
 test:
   <<: *defaults
   secret_key_base: aa52abc3f3a629d04a61e9899a24c12f52b24c679cbf45f8ec0cdcc64ab9526d673adca84212882dff3911ac98e0c32ec4729ca7b3429ba18ef4dfd1bd18bc7a
+  signing_key: aef3153a9829fa4ba10acb02927ac855df6b92795b1ad265d654443c4b14a017
   api_entreprise:
     key: api_entreprise_test_key
     base_url: https://entreprise.api.gouv.fr/v2

config/signing_key.yml

@@ -1,2 +0,0 @@
-# This is a signing key used in dev and test environments
-key: 'aef3153a9829fa4ba10acb02927ac855df6b92795b1ad265d654443c4b14a017'