Add retries to working_docker_image?

* Also synchronize images during save

app/controllers/execution_environments_controller.rb

@@ -15,9 +15,7 @@ class ExecutionEnvironmentsController < ApplicationController
   def create
     @execution_environment = ExecutionEnvironment.new(execution_environment_params)
     authorize!
-    create_and_respond(object: @execution_environment) do
-      sync_to_runner_management
-    end
+    create_and_respond(object: @execution_environment)
   end
 
   def destroy
@@ -165,9 +163,7 @@ class ExecutionEnvironmentsController < ApplicationController
   end
 
   def update
-    update_and_respond(object: @execution_environment, params: execution_environment_params) do
-      sync_to_runner_management
-    end
+    update_and_respond(object: @execution_environment, params: execution_environment_params)
   end
 
   def sync_all_to_runner_management
@@ -186,11 +182,4 @@ class ExecutionEnvironmentsController < ApplicationController
       redirect_to ExecutionEnvironment, alert: t('execution_environments.index.synchronize_all.failure')
     end
   end
-
-  def sync_to_runner_management
-    unless Runner.management_active? && Runner.strategy_class.sync_environment(@execution_environment)
-      t('execution_environments.form.errors.not_synced_to_runner_management')
-    end
-  end
-  private :sync_to_runner_management
 end

app/models/execution_environment.rb

@@ -79,13 +79,24 @@ class ExecutionEnvironment < ApplicationRecord
   private :validate_docker_image?
 
   def working_docker_image?
-    runner = Runner.for(author, self)
-    output = runner.execute_command(VALIDATION_COMMAND)
-    errors.add(:docker_image, "error: #{output[:stderr]}") if output[:stderr].present?
-  rescue Runner::Error::NotAvailable => e
-    Rails.logger.info("The Docker image could not be verified: #{e}")
-  rescue Runner::Error => e
-    errors.add(:docker_image, "error: #{e}")
+    sync_runner_environment
+    retries = 0
+    begin
+      runner = Runner.for(author, self)
+      output = runner.execute_command(VALIDATION_COMMAND)
+      errors.add(:docker_image, "error: #{output[:stderr]}") if output[:stderr].present?
+    rescue Runner::Error => e
+      # In case of an Runner::Error, we retry multiple times before giving up.
+      # The time between each retry increases to allow the runner management to catch up.
+      if retries < 5 && !Rails.env.test?
+        retries += 1
+        sleep retries
+        retry
+      elsif errors.exclude?(:docker_image)
+        errors.add(:docker_image, "error: #{e}")
+        raise ActiveRecord::RecordInvalid.new(self)
+      end
+    end
   end
 
   def delete_runner_environment