Add timed incremental rollout to Auto DevOps

Auto DevOps deployment strategies now supports timed incremental
rollout. We are deprecating the usage of INCREMENTAL_ROLLOUT_ENABLED
environment variable in Auto DevOps template.

The new behavior will be driven by the INCREMENTAL_ROLLOUT_MODE variable
that can either be manual (same as INCREMENTAL_ROLLOUT_ENABLED) or
timed.

Rollout deployments will be executed using a 5 minute delay between each
job.

2 files changed, 23 insertions, 6 deletions

diff --git a/app/models/project_auto_devops.rb b/app/models/project_auto_devops.rb
index dc6736dd9cd..2253ad7b543 100644
--- a/app/models/project_auto_devops.rb
+++ b/app/models/project_auto_devops.rb
@@ -5,7 +5,8 @@ class ProjectAutoDevops < ActiveRecord::Base
 
   enum deploy_strategy: {
     continuous: 0,
-    manual: 1
+    manual: 1,
+    timed_incremental: 2
   }
 
   scope :enabled, -> { where(enabled: true) }
@@ -30,10 +31,7 @@ class ProjectAutoDevops < ActiveRecord::Base
                          value: domain.presence || instance_domain)
       end
 
-      if manual?
-        variables.append(key: 'STAGING_ENABLED', value: '1')
-        variables.append(key: 'INCREMENTAL_ROLLOUT_ENABLED', value: '1')
-      end
+      variables.concat(deployment_strategy_default_variables)
     end
   end
 
@@ -51,4 +49,16 @@ class ProjectAutoDevops < ActiveRecord::Base
       !project.public? &&
       !project.deploy_tokens.find_by(name: DeployToken::GITLAB_DEPLOY_TOKEN_NAME).present?
   end
+
+  def deployment_strategy_default_variables
+    Gitlab::Ci::Variables::Collection.new.tap do |variables|
+      if manual?
+        variables.append(key: 'STAGING_ENABLED', value: '1')
+        variables.append(key: 'INCREMENTAL_ROLLOUT_ENABLED', value: '1') # deprecated
+        variables.append(key: 'INCREMENTAL_ROLLOUT_MODE', value: 'manual')
+      elsif timed_incremental?
+        variables.append(key: 'INCREMENTAL_ROLLOUT_MODE', value: 'timed')
+      end
+    end
+  end
 end
diff --git a/app/views/projects/settings/ci_cd/_autodevops_form.html.haml b/app/views/projects/settings/ci_cd/_autodevops_form.html.haml
index ab92b757836..5ec5a06396e 100644
--- a/app/views/projects/settings/ci_cd/_autodevops_form.html.haml
+++ b/app/views/projects/settings/ci_cd/_autodevops_form.html.haml
@@ -39,10 +39,17 @@
                   = form.label :deploy_strategy_continuous, class: 'form-check-label' do
                     = s_('CICD|Continuous deployment to production')
                     = link_to icon('question-circle'), help_page_path('topics/autodevops/index.md', anchor: 'auto-deploy'), target: '_blank'
+
+                .form-check
+                  = form.radio_button :deploy_strategy, 'timed_incremental', class: 'form-check-input'
+                  = form.label :deploy_strategy_timed_incremental, class: 'form-check-label' do
+                    = s_('CICD|Continuous deployment to production using timed incremental rollout')
+                    = link_to icon('question-circle'), help_page_path('topics/autodevops/index.md', anchor: 'timed-incremental-rollout-to-production'), target: '_blank'
+
                 .form-check
                   = form.radio_button :deploy_strategy, 'manual', class: 'form-check-input'
                   = form.label :deploy_strategy_manual, class: 'form-check-label' do
                     = s_('CICD|Automatic deployment to staging, manual deployment to production')
-                    = link_to icon('question-circle'), help_page_path('ci/environments.md', anchor: 'manually-deploying-to-environments'), target: '_blank'
+                    = link_to icon('question-circle'), help_page_path('topics/autodevops/index.md', anchor: 'incremental-rollout-to-production'), target: '_blank'
 
           = f.submit _('Save changes'), class: "btn btn-success prepend-top-15"