Hi all,

We are planning to introduce a new tool/script which would help with the problem of visibility of the changes done to Ceph configuration options. Currently there are two main limitations:

Changes to the configuration are missed in our release notes
No easy way to know what configuration have modified/added/deleted between two releases

Some context on ceph configuration management system:

The default values for all the configuration options for a ceph cluster when starting up are in the yaml files present in the `src/common/options` directory.

For example: `osd.yaml.in` file tells us all the configuration options available for `ceph-osd` daemon.

The config options from yaml files are directly injected to the `CephContext` and these files are the sole source of truth to know about the configurations present for all the systems of ceph. It is important to note that, the values in the yaml files only represent the default values with which the cluster starts with, any changes made to these config options are not reflected in the yaml files.

The detailed information about the configuration management is present here: https://docs.ceph.com/en/latest/dev/config/

Proposal to solve this problem is two fold:

1. Tool to compare configuration options between releases or commit hashes

A script which takes commit hashes or release names and diff the yaml files present in the `src/common/options` directory and output sections like: `Deleted`, `Added` and `Updated`
Developers can run this script whenever they wish to know the configuration diff between two releases
For example: `ceph-config-diff --mode diff-branch --ref-repo <repo-url> --ref-branch main --cmp-branch squid`, a command like this will compare the current main branch with the squid branch.

2. A Github action runs on every PR (it only executes when the yaml files are updated). This will be added as an optional check.

This action will check if any changes have occurred to yaml config files and write a comment to the PR notifying the PR author to also update the relevant release docs.
This action will reuse the script mentioned above to find the diff, if any present

I believe, these two options should help solve the current visibility problems in ceph configuration system.

Please let us know your thoughts about this feature. All inputs are welcome.

Thanks,

Naveen