Templates for Common Files in Operator Repositories

Stackable develops and maintains a growing number of operators for open source software.

The high level structure of the repository is consistent across all repositories, which in the past has led to repetitive maintenance tasks in many repositories even for small changes.

This repository is intended to help with these changes by keeping common files as templates and offering tooling to roll these out to all repositories that are under management by this tool.

Structure of this repository

GitHub Actions

The definition files for GitHub actions that in turn execute the playbooks doing the actual work are kept in .github

Playbook

playbook contains the ansible playbook which is executed to perform the needed changes.

Templates

Everything under the top level folder template is replicated to the target repositories. The folder and file structure under template is considered as source structure which will be synchronized across all repositories in the following manner:

• Regular files and folders are simply copied

• Files with an extension of .j2 will be processed as jinja2 templates and copied to the target repositories with the .j2 extension removed. The default jinja2 variable delimiter has been replaced with {[ }] since a lot of the template files contain {{ }} and caused issues.

• File and directory names which contain [[product]] will have this substituted for the value of the product_string variable. For example: "stackable-[[product]]-operator.service" would become stackable-kafka-operator.service.

To remove files or directories that already exist in the target repositories these need to be configured in repositories.yaml under the retired_files key.

Anything that is listed here will be deleted from the target repositories.

Note	Deletion is the last step that is performed, so if there is an overlap between files existing in the template folder and this setting, the files would not be rolled out, since they’d get deleted before creting the pull request.

Configuration

All user-facing configuration is kept in repositories.yaml.

The actions in this repository are set up so that the playbooks are automatically executed whenever a commit is made to the main branch of this repository.

So in principle it is as simple as pushing any commit to main which will trigger a sync of everything under template to all target repositories.

Target repositories are configured in repositories.yaml in the following form:

- name: kafka-operator
  url: stackabletech/kafka-operator.git
  product_string: kafka
  pretty_string: Kafka

Field	Description
name	This is only used internally to name working directories and the like.
url	The github repository for this operator. Need to be in the form of <org>/<repo>.git
product_string	A lower case string to use in config files, file names and the like. Should not contain whitespaces. This can sometimes be a shortened version of the full name, for example for Open Policy Agent this would be "opa"
pretty_string	The actual name of the product, including whitespaces and proper capitalization. This is intended to be used in doc or man files or similar things.
include_productconfig	Whether to include files from the deploy/config-spec folder into the os package. Default: true

These are the only variables currently being used on the playbooks, but can be extended easily as more are needed.

Note	If a new variable is introduced, it needs to be added to all repository objects!

Additional settings can be found in playbook/group_vars/all, but these are not intended to be freely changed and should be treated with care.

Making changes to the template

If you want to make a change that should be rolled out to all operators, make the change in the template directory. Consult the section above to learn more about the structure of the template.

Test changes locally

1. Create the directory work and run the test.sh script.

2. The changes can be examined with git status. When the pull request is later merged into the main branch then pull requests with these changes will be created automatically.

3. Depending on the change, it makes sense to run the integration tests for all changed operators. If the tests are not run in this stage and if there is even just one integration test failing in the subsequential generated pull requests then the operator-templating must be adapted which creates again pull requests for all operators. Changes in the GitHub workflow actions cannot be tested until finally merged.

Deploying changes

Changes are rolled out via GitHub actions.

Authentication

Since this tool needs to authenticate itself in order to push commits it needs credentials of a user. This is currently solved via a personal access token that needs to be provided as a repository (or org) secret with the name GH_ACCESS_TOKEN.

The personal access token needs to have the following permissions for this to work:

• repo

• org:read

• workflow

Limitations

There is currently no synchronization with existing PRs on the target repositories whatsoever. A new pull request will be created for every commit made to this repository.

To update a PR that was created via this tool, it will have to be closed and necessary changes pushed here, which will result in a new PR.

Warning

The Helm Chart files that are rolled out by the templates in their current form do not include a ClusterRole object which may be needed for this to work with RBAC.