Enabled variables for CI services

CI lint now validates the Services hash
even after adding a Variables hash

Variables are also returned in the Service object
when the runner requests a new Job

Changelog: added

lib/api/entities/ci/job_request/service.rb

@@ -6,6 +6,7 @@ module API
       module JobRequest
         class Service < Entities::Ci::JobRequest::Image
           expose :alias, :command
+          expose :variables
         end
       end
     end

lib/gitlab/ci/build/image.rb

@@ -4,7 +4,7 @@ module Gitlab
   module Ci
     module Build
       class Image
-        attr_reader :alias, :command, :entrypoint, :name, :ports
+        attr_reader :alias, :command, :entrypoint, :name, :ports, :variables
 
         class << self
           def from_image(job)
@@ -33,6 +33,7 @@ module Gitlab
             @entrypoint = image[:entrypoint]
             @name = image[:name]
             @ports = build_ports(image).select(&:valid?)
+            @variables = build_variables(image)
           end
         end
 
@@ -45,6 +46,12 @@ module Gitlab
         def build_ports(image)
           image[:ports].to_a.map { |port| ::Gitlab::Ci::Build::Port.new(port) }
         end
+
+        def build_variables(image)
+          image[:variables].to_a.map do |key, value|
+            { key: key.to_s, value: value.to_s }
+          end
+        end
       end
     end
   end

lib/gitlab/ci/config/entry/service.rb

@@ -15,7 +15,7 @@ module Gitlab
           include ::Gitlab::Config::Entry::Attributable
           include ::Gitlab::Config::Entry::Configurable
 
-          ALLOWED_KEYS = %i[name entrypoint command alias ports].freeze
+          ALLOWED_KEYS = %i[name entrypoint command alias ports variables].freeze
 
           validations do
             validates :config, hash_or_string: true
@@ -32,6 +32,10 @@ module Gitlab
           entry :ports, Entry::Ports,
             description: 'Ports used to expose the service'
 
+          entry :variables, ::Gitlab::Ci::Config::Entry::Variables,
+            description: 'Environment variables available for this service.',
+            inherit: false
+
           attributes :ports
 
           def alias
@@ -57,6 +61,10 @@ module Gitlab
             {}
           end
 
+          def variables
+            value[:variables]
+          end
+
           def with_image_ports?
             opt(:with_image_ports)
           end