GitLab Data Seeder

GitLab Data Seeder (GDS) is a test data seeding harness, that can seed test data into a user or group namespace.

The Data Seeder uses FactoryBot in the backend which makes maintenance straightforward. When a Model changes, FactoryBot already reflects the change.

Docker Setup

See Data Seeder Docker Demo

GDK Setup

$ gdk start db
ok: run: services/postgresql: (pid n) 0s, normally down
ok: run: services/redis: (pid n) 74s, normally down
$ bundle install
Bundle complete!
$ bundle exec rake db:migrate
main: migrated
ci: migrated


The ee:gitlab:seed:data_seeder Rake task takes two arguments. :name and :namespace_id.

$ bundle exec rake "ee:gitlab:seed:data_seeder[data_seeder,1]"
Seeding Data for Administrator


Where :name is the filename. (This name reflects relative .rb, .yml, or .json files located in ee/db/seeds/data_seeder, or absolute paths to seed files.)


Where :namespace_id is the ID of the User or Group Namespace


The Data Seeder uses FactoryBot definitions from spec/factories which …

  1. Saves time on development
  2. Are easy-to-read
  3. Are easy to maintain
  4. Do not rely on an API that may change in the future
  5. Are always up-to-date
  6. Execute on the lowest-level (ActiveRecord) possible to create data as quickly as possible

From the FactoryBot README : factory_bot is a fixtures replacement with a straightforward definition syntax, support for multiple build strategies (saved instances, unsaved instances, attribute hashes, and stubbed objects), and support for multiple factories for the same class, including factory inheritance

Factories reside in spec/factories/* and are fixtures for Rails models found in app/models/*. For example, For a model named app/models/issue.rb, the factory will be named spec/factories/issues.rb. For a model named app/models/project.rb, the factory will be named app/models/projects.rb.

There are three parsers that the GitLab Data Seeder supports. Ruby, YAML, and JSON.


All Ruby Seeds must define a DataSeeder class with a #seed instance method. You may structure your Ruby class as you wish. All FactoryBot methods (create, build, create_list) are included in the class automatically and may be called.

The DataSeeder class contains the following instance variables defined upon seeding:

  • @seed_file - The File object.
  • @owner - The owner of the seed data.
  • @name - The name of the seed. This is the seed filename without the extension.
  • @group - The root group that all seeded data is created under.
# frozen_string_literal: true

class DataSeeder
  def seed
    my_group = create(:group, name: 'My Group', path: 'my-group-path', parent: @group)
    my_project = create(:project, :public, name: 'My Project', namespace: my_group, creator: @owner)


The YAML Parser is a DSL that supports Factory definitions and allows you to seed data using a human-readable format.

name: My Seeder
  - _id: my_group
    name: My Group
    path: my-group-path

  - _id: my_project
    name: My Project
    namespace_id: <%= %>
    creator_id: <%= %>
      - public


The JSON Parser allows you to house seed files in JSON format.

  "name": "My Seeder",
  "groups": [
    { "_id": "my_group", "name": "My Group", "path": "my-group-path" }
  "projects": [
      "_id": "my_project",
      "name": "My Project",
      "namespace_id": "<%= %>",
      "creator_id": "<%= %>",
      "traits": ["public"]

Taxonomy of a Factory

Factories consist of three main parts - the Name of the factory, the Traits and the Attributes.

Given: create(:iteration, :with_title, :current, title: 'My Iteration')

:iterationThis is the Name of the factory. The filename will be the plural form of this Name and reside under either spec/factories/iterations.rb or ee/spec/factories/iterations.rb.
:with_titleThis is a Trait of the factory. See how it’s defined.
:currentThis is a Trait of the factory. See how it’s defined.
title: ‘My Iteration’This is an Attribute of the factory that is passed to the Model for creation.


In these examples, you will see an instance variable @owner. This is the root user (User.first).

Create a Group

my_group = create(:group, name: 'My Group', path: 'my-group-path')

Create a Project

# create a Project belonging to a Group
my_project = create(:project, :public, name: 'My Project', namespace: my_group, creator: @owner)

Create an Issue

# create an Issue belonging to a Project
my_issue = create(:issue, title: 'My Issue', project: my_project, weight: 2)

Create an Iteration

# create an Iteration under a Group
my_iteration = create(:iteration, :with_title, :current, title: 'My Iteration', group: my_group)

Frequently encountered issues

ActiveRecord::RecordInvalid: Validation failed: Email has already been taken, Username has already been taken

This is because, by default, our factories are written to backfill any data that is missing. For instance, when a project is created, the project must have somebody that created it. If the owner is not specified, the factory attempts to create it.

How to fix

Check the respective Factory to find out what key is required. Usually :author or :owner.

# This throws ActiveRecord::RecordInvalid
create(:project, name: 'Throws Error', namespace: create(:group, name: 'Some Group'))

# Specify the user where @owner is a [User] record
create(:project, name: 'No longer throws error', owner: @owner, namespace: create(:group, name: 'Some Group'))
create(:epic, group: create(:group), author: @owner)

parsing id "my id" as "my_id"

See specifying variables

id is invalid

Given that non-Ruby parsers parse IDs as Ruby Objects, the naming conventions of Ruby must be followed when specifying an ID.

Examples of invalid IDs:

  • IDs that start with a number
  • IDs that have special characters (-, !, $, @, `, =, <, >, ;, :)

ActiveRecord::AssociationTypeMismatch: Model expected, got … which is an instance of String

This is a limitation for the seeder.

See the issue for allowing parsing of raw Ruby objects.

YAML Factories

Generator to generate n amount of records

Group Labels

  # Group Label with Name and a Color
  - name: Group Label 1
    group_id: <%= %>
    color: "#FF0000"

Group Milestones

  # Past Milestone
  - name: Past Milestone
    group_id: <%= %>
    start_date: <%= 1.month.ago %>
    due_date: <%= %>

  # Ongoing Milestone
  - name: Ongoing Milestone
    group_id: <%= %>
    start_date: <%= %>
    due_date: <%= 1.month.from_now %>

  # Future Milestone
  - name: Ongoing Milestone
    group_id: <%= %>
    start_date: <%= 1.month.from_now %>
    due_date: <%= 2.months.from_now %>


  • You must specify group: and have it be empty. This is because the Milestones factory manipulates the factory in an after(:build). If this is not present, the Milestone cannot be associated properly with the Group.


  # Simple Epic
  - title: Simple Epic
    group_id: <%= %>
    author_id: <%= %>

  # Epic with detailed Markdown description
  - title: Detailed Epic
    group_id: <%= %>
    author_id: <%= %>
    description: |
      # Markdown


  # Epic with dates
  - title: Epic with dates
    group_id: <%= %>
    author_id: <%= %>
    start_date: <%= %>
    due_date: <%= 1.month.from_now %>


Each created factory can be assigned an identifier to be used in future seeding.

You can specify an ID for any created factory that you may use later in the seed file.

Specify a variable

You may pass an _id attribute on any factory to refer back to it later in non-Ruby parsers.

Variables are under the factory definitions that they reside in.

  - _id: my_label #=> group_labels.my_label

  - _id: my_project #=> projects.my_project


It is not advised, but you may specify variables with spaces. These variables may be referred back to with underscores.

Referencing a variable

Given a YAML seed file:

  - _id: my_group_label #=> group_labels.my_group_label
    name: My Group Label
    color: "#FF0000"
  - _id: my_other_group_label #=> group_labels.my_other_group_label
    color: <%= group_labels.my_group_label.color %>

  - _id: my_project #=> projects.my_project
    name: My Project

When referring to a variable, the variable refers to the already seeded models. In other words, the model’s id attribute will be populated.