Dependabot Core

Dependabot Core is the heart of Dependabot. It handles the logic for updating dependencies on GitHub (including GitHub Enterprise), GitLab and Azure DevOps.

If you want to host your own automated dependency update bot then this repo should give you the tools you need. A reference implementation is available here.

What's in this repo?

Dependabot Core is a collection of packages for automating dependency updating in Ruby, JavaScript, Python, PHP, Elixir, Elm, Go, Rust, Java and .NET. It can also update git submodules, Docker files and Terraform files. Highlights include:

• Logic to check for the latest version of a dependency that's resolvable given a project's other dependencies
• Logic to generate updated manifest and lockfiles for a new dependency version
• Logic to find changelogs, release notes, and commits for a dependency update

Other Dependabot resources

In addition to this library, you may be interested in:

• The dependabot-script repo, which provides a collection of scripts that use this library to update dependencies on GitHub Enterprise, GitLab or Azure DevOps
• The API docs for Dependabot's hosted instance (dependabot.com)

Setup

To run all of Dependabot Core, you'll need Ruby, Python, PHP, Elixir, Node, Go, Elm and Rust installed. However, if you just wish to run it for a single language you can get away with just having that language and Ruby.

The main library is written in Ruby, while JavaScript, Python, PHP, Elm, Elixir, Go and Rust are required for dealing with updates for their respective languages.

To install the helpers for each language:

1. cd npm_and_yarn/helpers && yarn install --production && cd -
2. cd composer/helpers && composer install --no-dev && cd -
3. cd python/helpers && pyenv exec pip install -r requirements.txt && cd -
4. cd hex/helpers && mix deps.get && cd -
5. cd terraform && helpers/build helpers/install-dir/terraform && cd -

Local development

Run the tests by running rspec spec inside each of the packages. Style is enforced by RuboCop. To check for style violations, simply run rubocop in each of the packages.

Running with Docker

While you can run Dependabot Core without Docker, we also provide a development Dockerfile. In most cases, you'll be better off running Dependabot in the development Docker container as it bakes in all required dependencies.

Start by building the initial Dependabot Core image, or pull it from the Docker registry.

$ docker pull dependabot/dependabot-core # OR
$ docker build -t dependabot/dependabot-core . # this may take a while

Once you have the base Docker image, you can build and run the development container using the docker-dev-shell script. The script will automatically build the container if it's not present, and can be forced to rebuild with the --rebuild flag. The image includes all dependencies, and the script runs the image, mounting the local copy of Dependabot Core so changes made locally will be reflected inside the container. This means you can continue to use your editor of choice, while running the tests inside the container.

$ bin/docker-dev-shell
=> building image from Dockerfile.development
=> running docker development shell
[dependabot-core-dev] ~/dependabot-core $

Dry run script

Note: you must have run bundle install in the omnibus directory before running this script.

You can use the "dry-run" script to simulate a dependency update job, printing the diff that would be generated to the terminal. It takes two positional arguments: the package manager and the GitHub repo name (including the account):

$ cd omnibus && bundle install && cd -
$ bin/dry-run.rb go_modules rsc/quote
=> fetching dependency files
=> parsing dependency files
=> updating 2 dependencies
...

Releasing

Triggering the jobs that will push the new gems is done by the following the steps below.

• Ensure you have the latest merged changes: git checkout master and git pull
• Generate an updated CHANGELOG, version.rb, and the rest of the needed commands: bin/bump-version.rb patch
• Edit the CHANGELOG file and remove any entries that aren't needed
• Run the commands that were output by running bin/bump-version.rb patch

Architecture

Dependabot Core is a collection of Ruby packages (gems), which contain the logic for updating dependencies in a number of languages.

dependabot-common

The common package contains all general-purpose / shared functionality. For instance the code for creating pull requests via GitHub's API lives here, as does most of the logic for handling Git dependencies (as most languages support Git dependencies in one way or another). There are also base classes defined for each of the major concerns required to implement support for a language or package manager.

dependabot-{package-manager}

There is a gem for each package manager or language that Dependabot supports. At a minimum, each of these gems will implement the following classes:

Service	Description
FileFetcher	Fetches the relevant dependency files for a project (e.g., the Gemfile and Gemfile.lock). See the README for more details.
FileParser	Parses a dependency file and extracts a list of dependencies for a project. See the README for more details.
UpdateChecker	Checks whether a given dependency is up-to-date. See the README for more details.
FileUpdater	Updates a dependency file to use the latest version of a given dependency. See the README for more details.
MetadataFinder	Looks up metadata about a dependency, such as its GitHub URL. See the README for more details.
Version	Describes the logic for comparing dependency versions. See the hex Version class for an example.
Requirement	Describes the format of a dependency requirement (e.g. >= 1.2.3). See the hex Requirement class for an example.

The high level flow looks like this:

dependabot-omnibus

This is a "meta" gem, that simply depends on all the others. If you want to automatically include support for all languages, you can just include this gem and you'll get all you need.

Why is this public?

As the name suggests, Dependabot Core is the core of Dependabot (the rest of the app is pretty much just a UI and database). If we were paranoid about someone stealing our business then we'd be keeping it under lock and key.

Dependabot Core is public because we're more interested in it having an impact than we are in making a buck from it. We'd love you to use Dependabot, so that we can continue to develop it, but if you want to build and host your own version then this library should make doing so a lot easier.

If you use Dependabot Core then we'd love to hear what you build!

License

We use the License Zero Prosperity Public License, which essentially enshrines the following:

• If you would like to use Dependabot Core in a non-commercial capacity, such as to host a bot at your workplace, then we give you full permission to do so. In fact, we'd love you to, and will help and support you however we can.
• If you would like to add Dependabot's functionality to your for-profit company's offering then we DO NOT give you permission to use Dependabot Core to do so. Please contact us directly to discuss a partnership or licensing arrangement.

If you make a significant contribution to Dependabot Core then you will be asked to transfer the IP of that contribution to Dependabot Ltd so that it can be licensed in the same way as the above.

History

Dependabot and Dependabot Core started life as Bump and Bump Core, back when Harry and Grey were working at GoCardless. We remain grateful for the help and support of GoCardless in helping make Dependabot possible - if you need to collect recurring payments from Europe, check them out.