Extract logic who created deployment into Deployment#deployed_by

Prefer the deployable user over the deployment user.

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/66037.

app/models/deployment.rb

@@ -162,6 +162,14 @@ class Deployment < ApplicationRecord
     deployed_at&.to_time&.in_time_zone&.to_s(:medium)
   end
 
+  def deployed_by
+    # We use deployable's user if available because Ci::PlayBuildService
+    # does not update the deployment's user, just the one for the deployable.
+    # TODO: use deployment's user once https://gitlab.com/gitlab-org/gitlab-ce/issues/66442
+    # is completed.
+    deployable&.user || user
+  end
+
   private
 
   def ref_path

app/serializers/deployment_entity.rb

@@ -21,7 +21,7 @@ class DeploymentEntity < Grape::Entity
   expose :finished_at
   expose :tag
   expose :last?
-  expose :user, using: UserEntity
+  expose :deployed_by, as: :user, using: UserEntity
 
   expose :deployable do |deployment, opts|
     deployment.deployable.yield_self do |deployable|

app/views/projects/deployments/_deployment.html.haml

@@ -15,10 +15,10 @@
           .flex-truncate-child
             = link_to [@project.namespace.becomes(Namespace), @project, deployment.deployable], class: 'build-link' do
               #{deployment.deployable.name} (##{deployment.deployable.id})
-        - if deployment.user
+        - if deployment.deployed_by
           %div
             by
-            = user_avatar(user: deployment.user, size: 20, css_class: "mr-0 float-none")
+            = user_avatar(user: deployment.deployed_by, size: 20, css_class: "mr-0 float-none")
 
   .table-section.section-15{ role: 'gridcell' }
     .table-mobile-header{ role: 'rowheader' }= _("Created")

changelogs/unreleased/66037-deployment-user.yml

@@ -0,0 +1,5 @@
+---
+title: Return correct user for manual deployments
+merge_request: 32004
+author:
+type: fixed

spec/models/deployment_spec.rb

@@ -322,4 +322,30 @@ describe Deployment do
       end
     end
   end
+
+  describe '#deployed_by' do
+    it 'returns the deployment user if there is no deployable' do
+      deployment_user = create(:user)
+      deployment = create(:deployment, deployable: nil, user: deployment_user)
+
+      expect(deployment.deployed_by).to eq(deployment_user)
+    end
+
+    it 'returns the deployment user if the deployable have no user' do
+      deployment_user = create(:user)
+      build = create(:ci_build, user: nil)
+      deployment = create(:deployment, deployable: build, user: deployment_user)
+
+      expect(deployment.deployed_by).to eq(deployment_user)
+    end
+
+    it 'returns the deployable user if there is one' do
+      build_user = create(:user)
+      deployment_user = create(:user)
+      build = create(:ci_build, user: build_user)
+      deployment = create(:deployment, deployable: build, user: deployment_user)
+
+      expect(deployment.deployed_by).to eq(build_user)
+    end
+  end
 end