Application limits development
This document provides a development guide for contributors to add application limits to GitLab.
Documentation
First of all, you have to gather information and decide which are the different limits that are set for the different GitLab tiers. Coordinate with others to document and communicate those limits.
There is a guide about introducing application limits.
Implement plan limits
Insert database plan limits
In the plan_limits
table, create a new column and insert the limit values.
It’s recommended to create two separate migration script files.
-
Add a new column to the
plan_limits
table with non-null default value that represents desired limit, such as:add_column(:plan_limits, :project_hooks, :integer, default: 100, null: false)
Plan limits entries set to
0
mean that limits are not enabled. You should use this setting only in special and documented circumstances. -
(Optionally) Create the database migration that fine-tunes each level with a desired limit using
create_or_update_plan_limit
migration helper, such as:class InsertProjectHooksPlanLimits < Gitlab::Database::Migration[2.1] def up create_or_update_plan_limit('project_hooks', 'default', 0) create_or_update_plan_limit('project_hooks', 'free', 10) create_or_update_plan_limit('project_hooks', 'bronze', 20) create_or_update_plan_limit('project_hooks', 'silver', 30) create_or_update_plan_limit('project_hooks', 'premium', 30) create_or_update_plan_limit('project_hooks', 'premium_trial', 30) create_or_update_plan_limit('project_hooks', 'gold', 100) create_or_update_plan_limit('project_hooks', 'ultimate', 100) create_or_update_plan_limit('project_hooks', 'ultimate_trial', 100) end def down create_or_update_plan_limit('project_hooks', 'default', 0) create_or_update_plan_limit('project_hooks', 'free', 0) create_or_update_plan_limit('project_hooks', 'bronze', 0) create_or_update_plan_limit('project_hooks', 'silver', 0) create_or_update_plan_limit('project_hooks', 'premium', 0) create_or_update_plan_limit('project_hooks', 'premium_trial', 0) create_or_update_plan_limit('project_hooks', 'gold', 0) create_or_update_plan_limit('project_hooks', 'ultimate', 0) create_or_update_plan_limit('project_hooks', 'ultimate_trial', 0) end end
Some plans exist only on GitLab.com. This is a no-op for plans that do not exist.
Plan limits validation
Get current limit
Access to the current limit can be done through the project or the namespace, such as:
project.actual_limits.project_hooks
Check current limit
There is one method PlanLimits#exceeded?
to check if the current limit is
being exceeded. You can use either an ActiveRecord
object or an Integer
.
Ensures that the count of the records does not exceed the defined limit, such as:
project.actual_limits.exceeded?(:project_hooks, ProjectHook.where(project: project))
Ensures that the number does not exceed the defined limit, such as:
project.actual_limits.exceeded?(:project_hooks, 10)
Limitable
concern
The Limitable
concern
can be used to validate that a model does not exceed the limits. It ensures
that the count of the records for the current model does not exceed the defined
limit.
You must specify the limit scope of the object being validated and the limit name if it’s different from the pluralized model name.
class ProjectHook
include Limitable
self.limit_name = 'project_hooks' # Optional as ProjectHook corresponds with project_hooks
self.limit_scope = :project
end
To test the model, you can include the shared examples.
it_behaves_like 'includes Limitable concern' do
subject { build(:project_hook, project: create(:project)) }
end
Testing instance-wide limits
Instance-wide features always use default
Plan, as instance-wide features
do not have license assigned.
class InstanceVariable
include Limitable
self.limit_name = 'instance_variables' # Optional as InstanceVariable corresponds with instance_variables
self.limit_scope = Limitable::GLOBAL_SCOPE
end
Subscription Plans
The opensource
plan was introduced in GitLab 14.7.
Self-managed:
-
default
: Everyone.
GitLab.com:
-
default
: Any system-wide feature. -
free
: Namespaces and projects with a Free subscription. -
bronze
: Namespaces and projects with a Bronze subscription. This tier is no longer available for purchase. -
silver
: Namespaces and projects with a Premium subscription. -
premium
: Namespaces and projects with a Premium subscription. -
premium_trial
: Namespaces and projects with a Premium Trial subscription. -
gold
: Namespaces and projects with an Ultimate subscription. -
ultimate
: Namespaces and projects with an Ultimate subscription. -
ultimate_trial
: Namespaces and projects with an Ultimate Trial subscription. -
opensource
: Namespaces and projects that are member of GitLab Open Source program.
The test
environment doesn’t have any plans.
Implement rate limits using Rack::Attack
We use the Rack::Attack
middleware to throttle Rack requests.
This applies to Rails controllers, Grape endpoints, and any other Rack requests.
The process for adding a new throttle is loosely:
- Add new columns to the
ApplicationSetting
model (*_enabled
,*_requests_per_period
,*_period_in_seconds
). - Extend
Gitlab::RackAttack
andGitlab::RackAttack::Request
to configure the new rate limit, and apply it to the desired requests. - Add the new settings to the Admin Area form in
app/views/admin/application_settings/_ip_limits.html.haml
. - Document the new settings in User and IP rate limits and Application settings API.
- Configure the rate limit for GitLab.com and document it in GitLab.com-specific rate limits.
Refer to these past issues for implementation details:
- Create a separate rate limit for the Files API.
- Create a separate rate limit for unauthenticated API traffic.
Implement rate limits using Gitlab::ApplicationRateLimiter
This module implements a custom rate limiter that can be used to throttle
certain actions. Unlike Rack::Attack
and Rack::Throttle
, which operate at
the middleware level, this can be used at the controller or API level.
See the CheckRateLimit
concern for use in controllers. In other parts of the code
the Gitlab::ApplicationRateLimiter
module can be called directly.
Next rate limiting architecture
In May 2022 we’ve started working on the next iteration of our application limits framework using a forward looking rate limiting architecture.
We are working on defining new requirements and designing the next architecture, so if you need new functionalities to add new limits, instead of building them right now, consider contributing to the Rate Limiting Architecture Working Group
Examples of what features we might want to build into the next iteration of rate limiting architecture:
- Making it possible to define and override limits per namespace / per plan.
- Automatically generating documentation about what limits are implemented and what the defaults are.
- Defining limits in a single place that can be found and explored.
- Soft and hard limits, with support for notifying users when a limit is approaching.