Use explicitly tracked deployments for MR widgets

When displaying the deployments of a merge request in the MR widget, we
used to rely on the latest CI pipeline to determine what the deployment
was. In this commit we add the ability to use the table
"deployment_merge_requests" to display the deployments of a merge
request. This way the data displayed remains the same, regardless of the
state of any CI pipelines.

These changes are currently hidden behind the
"deployment_merge_requests_widget" project feature flag. We do not
reuse the existing deployments feature flag, as we still want to record
merge requests even if the UI is not able to display the data properly.

app/controllers/projects/merge_requests_controller.rb

@@ -218,11 +218,16 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
   end
 
   def ci_environments_status
-    environments = if ci_environments_status_on_merge_result?
-                     EnvironmentStatus.after_merge_request(@merge_request, current_user)
-                   else
-                     EnvironmentStatus.for_merge_request(@merge_request, current_user)
-                   end
+    environments =
+      if ci_environments_status_on_merge_result?
+        if Feature.enabled?(:deployment_merge_requests_widget, @project)
+          EnvironmentStatus.for_deployed_merge_request(@merge_request, current_user)
+        else
+          EnvironmentStatus.after_merge_request(@merge_request, current_user)
+        end
+      else
+        EnvironmentStatus.for_merge_request(@merge_request, current_user)
+      end
 
     render json: EnvironmentStatusSerializer.new(current_user: current_user).represent(environments)
   end

app/models/environment_status.rb

@@ -20,6 +20,28 @@ class EnvironmentStatus
     build_environments_status(mr, user, mr.merge_pipeline)
   end
 
+  def self.for_deployed_merge_request(mr, user)
+    statuses = []
+
+    mr.recent_visible_deployments.each do |deploy|
+      env = deploy.environment
+
+      next unless Ability.allowed?(user, :read_environment, env)
+
+      statuses <<
+        EnvironmentStatus.new(deploy.project, env, mr, deploy.sha)
+    end
+
+    # Existing projects that used deployments prior to the introduction of
+    # explicitly linked merge requests won't have any data using this new
+    # approach, so we fall back to retrieving deployments based on CI pipelines.
+    if statuses.any?
+      statuses
+    else
+      after_merge_request(mr, user)
+    end
+  end
+
   def initialize(project, environment, merge_request, sha)
     @project = project
     @environment = environment

app/models/merge_request.rb

@@ -73,6 +73,14 @@ class MergeRequest < ApplicationRecord
   has_many :merge_request_assignees
   has_many :assignees, class_name: "User", through: :merge_request_assignees
 
+  has_many :deployment_merge_requests
+
+  # These are deployments created after the merge request has been merged, and
+  # the merge request was tracked explicitly (instead of implicitly using a CI
+  # build).
+  has_many :deployments,
+    through: :deployment_merge_requests
+
   KNOWN_MERGE_PARAMS = [
     :auto_merge_strategy,
     :should_remove_source_branch,
@@ -1472,6 +1480,10 @@ class MergeRequest < ApplicationRecord
     true
   end
 
+  def recent_visible_deployments
+    deployments.visible.includes(:environment).order(id: :desc).limit(10)
+  end
+
   private
 
   def with_rebase_lock

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -1280,6 +1280,28 @@ describe Projects::MergeRequestsController do
       end
     end
 
+    it 'uses the explicitly linked deployments' do
+      expect(EnvironmentStatus)
+        .to receive(:for_deployed_merge_request)
+        .with(merge_request, user)
+        .and_call_original
+
+      get_ci_environments_status(environment_target: 'merge_commit')
+    end
+
+    context 'when the deployment_merge_requests_widget feature flag is disabled' do
+      it 'uses the deployments retrieved using CI builds' do
+        stub_feature_flags(deployment_merge_requests_widget: false)
+
+        expect(EnvironmentStatus)
+          .to receive(:after_merge_request)
+          .with(merge_request, user)
+          .and_call_original
+
+        get_ci_environments_status(environment_target: 'merge_commit')
+      end
+    end
+
     def get_ci_environments_status(extra_params = {})
       params = {
         namespace_id: merge_request.project.namespace.to_param,

spec/lib/gitlab/import_export/all_models.yml

@@ -139,6 +139,8 @@ merge_requests:
 - blocking_merge_requests
 - blocked_merge_requests
 - description_versions
+- deployment_merge_requests
+- deployments
 external_pull_requests:
 - project
 merge_request_diff:

spec/models/environment_status_spec.rb

@@ -92,6 +92,84 @@ describe EnvironmentStatus do
     end
   end
 
+  describe '.for_deployed_merge_request' do
+    context 'when a merge request has no explicitly linked deployments' do
+      it 'returns the statuses based on the CI pipelines' do
+        mr = create(:merge_request, :merged)
+
+        expect(described_class)
+          .to receive(:after_merge_request)
+          .with(mr, mr.author)
+          .and_return([])
+
+        statuses = described_class.for_deployed_merge_request(mr, mr.author)
+
+        expect(statuses).to eq([])
+      end
+    end
+
+    context 'when a merge request has explicitly linked deployments' do
+      let(:merge_request) { create(:merge_request, :merged) }
+
+      let(:environment) do
+        create(:environment, project: merge_request.target_project)
+      end
+
+      it 'returns the statuses based on the linked deployments' do
+        deploy = create(
+          :deployment,
+          :success,
+          project: merge_request.target_project,
+          environment: environment,
+          deployable: nil
+        )
+
+        deploy.link_merge_requests(merge_request.target_project.merge_requests)
+
+        statuses = described_class
+          .for_deployed_merge_request(merge_request, merge_request.author)
+
+        expect(statuses.length).to eq(1)
+        expect(statuses[0].environment).to eq(environment)
+        expect(statuses[0].merge_request).to eq(merge_request)
+      end
+
+      it 'excludes environments the user can not see' do
+        deploy = create(
+          :deployment,
+          :success,
+          project: merge_request.target_project,
+          environment: environment,
+          deployable: nil
+        )
+
+        deploy.link_merge_requests(merge_request.target_project.merge_requests)
+
+        statuses = described_class
+          .for_deployed_merge_request(merge_request, create(:user))
+
+        expect(statuses).to be_empty
+      end
+
+      it 'excludes deployments that have the status "created"' do
+        deploy = create(
+          :deployment,
+          :created,
+          project: merge_request.target_project,
+          environment: environment,
+          deployable: nil
+        )
+
+        deploy.link_merge_requests(merge_request.target_project.merge_requests)
+
+        statuses = described_class
+          .for_deployed_merge_request(merge_request, merge_request.author)
+
+        expect(statuses).to be_empty
+      end
+    end
+  end
+
   describe '.build_environments_status' do
     subject { described_class.send(:build_environments_status, merge_request, user, pipeline) }
 

spec/models/merge_request_spec.rb

@@ -3376,4 +3376,56 @@ describe MergeRequest do
       ])
     end
   end
+
+  describe '#recent_visible_deployments' do
+    let(:merge_request) { create(:merge_request) }
+
+    let(:environment) do
+      create(:environment, project: merge_request.target_project)
+    end
+
+    it 'returns visible deployments' do
+      created = create(
+        :deployment,
+        :created,
+        project: merge_request.target_project,
+        environment: environment
+      )
+
+      success = create(
+        :deployment,
+        :success,
+        project: merge_request.target_project,
+        environment: environment
+      )
+
+      failed = create(
+        :deployment,
+        :failed,
+        project: merge_request.target_project,
+        environment: environment
+      )
+
+      merge_request.deployment_merge_requests.create!(deployment: created)
+      merge_request.deployment_merge_requests.create!(deployment: success)
+      merge_request.deployment_merge_requests.create!(deployment: failed)
+
+      expect(merge_request.recent_visible_deployments).to eq([failed, success])
+    end
+
+    it 'only returns a limited number of deployments' do
+      20.times do
+        deploy = create(
+          :deployment,
+          :success,
+          project: merge_request.target_project,
+          environment: environment
+        )
+
+        merge_request.deployment_merge_requests.create!(deployment: deploy)
+      end
+
+      expect(merge_request.recent_visible_deployments.count).to eq(10)
+    end
+  end
 end