Adds es:up Docker task to run Elasticsearch from current STACK_VERSION

Author: picandocodigo

CONTRIBUTING.md

@@ -34,6 +34,8 @@ rake docker:start[VERSION]
 E.g.: `rake docker:start[8.0-SNAPSHOT]`.
 To start the container with Platinum, pass it in as a parameter: `rake docker:start[7.x-SNAPSHOT,platinum]`.
 
+There's another rake task that will read the STACK_VERSION value from `.buildkite/pipeline.yml` and run that version of Elasticsearch: `rake es:up`.
+
 If you get this error when running the script:
 ```
 max virtual memory areas vm.max_map_count [65530] likely too low, increase to at least [262144]

rake_tasks/docker_tasks.rake

@@ -38,3 +38,18 @@ namespace :docker do
     system("STACK_VERSION=#{params[:version]} TEST_SUITE=#{test_suite} ./.ci/run-elasticsearch.sh")
   end
 end
+
+namespace :es do
+  desc <<~DOC
+    Start Elasticsearch docker container (shortcut), reads STACK_VERSION from buildkite pipeline
+  DOC
+  task :up do
+    version = File.read('./.buildkite/pipeline.yml').
+                split("\n").
+                select { |a| a.include? 'STACK_VERSION' }
+                .first
+                .strip
+                .gsub('STACK_VERSION: ','')
+    Rake.application.invoke_task("docker:start[#{version}]")
+  end
+end