Add Image Resizer config defaults

changelogs/unreleased/add-img-resizing-configs.yml

+---
+title: Add Image Resizer config defaults
+merge_request: 4639
+author:
+type: other

files/gitlab-config-template/gitlab.rb.template

@@ -841,6 +841,16 @@ external_url 'GENERATED_EXTERNAL_URL'
 #   'SSL_CERT_DIR' => "/opt/gitlab/embedded/ssl/certs/"
 # }
+##! Resource limitations for the dynamic image scaler.
+##! Exceeding these thresholds will cause Workhorse to serve images in their original size.
+##!
+##! Maximum number of scaler processes that are allowed to execute concurrently.
+##! It is recommended for this not to exceed the number of CPUs available.
+# gitlab_workhorse['image_scaler_max_procs'] = 4
+##!
+##! Maximum file size in bytes for an image to be considered eligible for rescaling
+# gitlab_workhorse['image_scaler_max_filesize'] = 250000
+
 ################################################################################
 ## GitLab User Settings
 ##! Modify default git user.

files/gitlab-cookbooks/gitlab/attributes/default.rb

@@ -644,6 +644,8 @@ default['gitlab']['gitlab-workhorse']['env'] = {
   'HOME' => node['gitlab']['user']['home'],
   'SSL_CERT_DIR' => "#{node['package']['install-dir']}/embedded/ssl/certs/"
 }
+default['gitlab']['gitlab-workhorse']['image_scaler_max_procs'] = [2, node['cpu']['total'].to_i / 2].max
+default['gitlab']['gitlab-workhorse']['image_scaler_max_filesize'] = 250_000
 ####
 # mailroom

files/gitlab-cookbooks/gitlab/recipes/gitlab-workhorse.rb

@@ -87,13 +87,25 @@ config_file_path = File.join(working_dir, "config.toml")
 object_store = node['gitlab']['gitlab-rails']['object_store']
 provider = object_store.dig('connection', 'provider')
 object_store_provider = provider if %w(AWS AzureRM).include?(provider)
+image_scaler_max_procs = node['gitlab']['gitlab-workhorse']['image_scaler_max_procs']
+image_scaler_max_filesize = node['gitlab']['gitlab-workhorse']['image_scaler_max_filesize']
 template config_file_path do
   source "workhorse-config.toml.erb"
   owner "root"
   group account_helper.gitlab_group
   mode "0640"
-  variables(object_store: object_store, object_store_provider: object_store_provider, redis_url: redis_url, password: redis_password, sentinels: redis_sentinels, sentinel_master: redis_sentinel_master, master_password: redis_sentinel_master_password)
+  variables(
+    object_store: object_store,
+    object_store_provider: object_store_provider,
+    redis_url: redis_url,
+    password: redis_password,
+    sentinels: redis_sentinels,
+    sentinel_master: redis_sentinel_master,
+    master_password: redis_sentinel_master_password,
+    image_scaler_max_procs: image_scaler_max_procs,
+    image_scaler_max_filesize: image_scaler_max_filesize
+  )
   notifies :restart, "runit_service[gitlab-workhorse]"
   notifies :run, 'bash[Set proper security context on ssh files for selinux]', :delayed if SELinuxHelper.enabled?
 end

files/gitlab-cookbooks/gitlab/templates/default/workhorse-config.toml.erb

@@ -22,3 +22,7 @@ Password = "<%= @master_password %>"
   azure_storage_access_key = "<%= @object_store.dig('connection', 'azure_storage_access_key') %>"
 <%- end %>
 <%- end %>
+
+[image_resizer]
+  max_scaler_procs = <%= @image_scaler_max_procs %>
+  max_filesize = <%= @image_scaler_max_filesize %>

spec/chef/recipes/gitlab-workhorse_spec.rb

 require 'chef_helper'
 RSpec.describe 'gitlab::gitlab-workhorse' do
-  let(:chef_run) { ChefSpec::SoloRunner.new(step_into: %w(runit_service)).converge('gitlab::default') }
+  let(:node_cpus) { 1 }
+  let(:chef_run) do
+    ChefSpec::SoloRunner.new(step_into: %w(runit_service)) do |node|
+      node.automatic['cpu']['total'] = node_cpus
+    end.converge('gitlab::default')
+  end
   let(:default_vars) do
     {
       'SSL_CERT_DIR' => '/opt/gitlab/embedded/ssl/certs/',
@@ -408,4 +413,51 @@ RSpec.describe 'gitlab::gitlab-workhorse' do
       expect(chef_run).not_to render_file("/var/opt/gitlab/gitlab-workhorse/config.toml").with_content(content_url)
     end
   end
+
+  context 'image scaler' do
+    context 'with default values' do
+      it 'sets the default maximum file size' do
+        expect(chef_run).to render_file(config_file).with_content { |content|
+          expect(content).to match(/\[image_resizer\]\n  max_scaler_procs = \d+\n  max_filesize = 250000/m)
+        }
+      end
+
+      context 'when reported CPU cores are at least 4' do
+        let(:node_cpus) { 4 }
+
+        it 'sets default max procs to half the number of cores' do
+          expect(chef_run).to render_file(config_file).with_content { |content|
+            expect(content).to match(/\[image_resizer\]\n  max_scaler_procs = 2/m)
+          }
+        end
+      end
+
+      context 'when reported CPU cores are less than 4' do
+        let(:node_cpus) { 3 }
+
+        it 'pins default max procs to 2' do
+          expect(chef_run).to render_file(config_file).with_content { |content|
+            expect(content).to match(/\[image_resizer\]\n  max_scaler_procs = 2/m)
+          }
+        end
+      end
+    end
+
+    context 'with custom values' do
+      before do
+        stub_gitlab_rb(
+          gitlab_workhorse: {
+            image_scaler_max_procs: 5,
+            image_scaler_max_filesize: 1024
+          }
+        )
+      end
+
+      it 'should generate config file with the specified values' do
+        expect(chef_run).to render_file(config_file).with_content { |content|
+          expect(content).to match(/\[image_resizer\]\n  max_scaler_procs = 5\n  max_filesize = 1024/m)
+        }
+      end
+    end
+  end
 end