gem

gem is the Gardener Extension Manager - not to be confused with Rubygems of course.

When working with Gardener, you'll always want to use extensions. Extensions come in the form of of controller-registration.yaml files. These files register an extension provider in Gardener so that it can then make use of its functionality when creating a Shoot cluster. More on this topic can be found in the Gardener repository.

One issue when working with extensions is to get the right set of versions. gem is a command line tool & library that addresses this issue by providing means to define extension requirements, resolve them to exact revisions and then download them into one controller-registrations.yaml file (one big YAML that contains all controller-registration.yaml files as a list).

Installation

To install gem, you need a working go installation >1.11. Once you have it, cd to an empty, temporary directory (in order not to mess up any go project) and run

GO111MODULE=on go get github.com/gardener/gem

Usage

In order to use gem you need to define a requirements.yaml. An example can be found here. In this file, you list your required gardener extensions.

For a requirement, you always have to specify a name and either a revision, version or branch. Optionally, you can also specify a filename, if the name of controller-registration is not the default controller-registration.yaml.

Once you've successfully defined a requirements.yaml file, gem provides the following commands to work with it, though the most important one will probably be ensure:

• solve: tries to solve the requirements given in your requirements.yaml and write it into a locks.yaml.

• fetch: requires a locks.yaml to be present. Fetches the controller-registrations specified via the requirements and locks.

• ensure: ensures that the controller-registrations you specified in your requirements.yaml are present and up to date. It can optionally also update your dependencies to the latest allowed version.