Merge branch 'jejacks0n/provide-default-context-key-strategy' into 'master'

Provide default context key hashing strategy

See merge request gitlab-org/gitlab!62414

config/initializers/gitlab_experiment.rb

@@ -5,4 +5,13 @@ Gitlab::Experiment.configure do |config|
   config.cache = Gitlab::Experiment::Cache::RedisHashStore.new(
     pool: ->(&block) { Gitlab::Redis::SharedState.with { |redis| block.call(redis) } }
   )
+
+  # TODO: This will be deprecated as of v0.6.0, but needs to stay intact for
+  #  actively running experiments until a versioning concept is put in place to
+  #  enable migrating into the new SHA2 strategy.
+  config.context_hash_strategy = lambda do |source, seed|
+    source = source.keys + source.values if source.is_a?(Hash)
+    data = Array(source).map { |v| (v.respond_to?(:to_global_id) ? v.to_global_id : v).to_s }
+    Digest::MD5.hexdigest(data.unshift(seed).join('|'))
+  end
 end