Adding an experimental ops file to enable cflinuxfs5.

[AttilaAlmasi]

WHAT is this change about?

As part of the validation process for the new cflinuxfs5 stack we introduce a new experimental ops file which will serve alongside the cflinuxfs4 stack.

Please describe the change.

• Added new add-cflinuxfs5.yml ops file. j
• Updated the README.md
• added the new file reference to the tests

What customer problem is being addressed? Use customer persona to define the problem e.g. Alana is unable to...

Since cflinuxfs4 is based on Jammy which is end of life in 2027 we need to introduce the new cflinuxfs5 stack which is based on Ubuntu Noble.

Please provide any contextual information.

Include any links to other PRs, stories, slack discussions, etc... that will help establish context.
https://github.com/cloudfoundry/community/blob/main/toc/rfc/rfc-0039-noble-based-cflinuxfs5.md

Has a cf-deployment including this change passed cf-acceptance-tests?

• YES
• NO

Does this PR introduce a breaking change? Please take a moment to read through the examples before answering the question.

• YES - please choose the category from below. Feel free to provide additional details.
• NO

Types of breaking changes:

1. causes app or operator downtime
2. increases VM footprint of cf-deployment - e.g. new jobs, new add ons, increases # of instances etc.
3. modifies, deletes or moves the name of a job or instance group in the main manifest
4. modifies the name or deletes a property of a job or instance group in the main manifest
5. changes the name of credentials in the main manifest
6. requires out-of-band manual intervention on the part of the operator
7. modifies the ops-file path, changes the type, changes the values or removes ops-files from the following folders
   • ./operations/ or ./operations/experimental
   • ./addons
   • ./backup-and-restore/

If you're promoting an experimental Ops-file (or removing one), Please follow the Ops-file workflows.

Ops files changes in the following folders are considered as NON BREAKING CHANGES
./community, ./example-vars-files, ./test

How should this change be described in cf-deployment release notes?

Added experimental ops file for cflinuxfs5

Something brief that conveys the change and is written with the persona (Alana, Cody...) in mind. See previous release notes for examples.

Does this PR introduce a new BOSH release into the base cf-deployment.yml manifest or any ops-files?

• YES - please specify
• NO

Does this PR make a change to an experimental or GA'd feature/component?

• experimental feature/component
• GA'd feature/component

Please provide Acceptance Criteria for this change?

CATs test should be running green.
Apps are deployable with the cflinuxfs5 stack

Please specify either bosh cli or cf cli commands for our team (and cf operators) to verify the changes.

Few examples

1. For a PR with a new job in the manifest, bosh instances can verify the job is running after upgrade. You can provide additional commands to verify the job is running as specified.
2. For a PR with new variables, bosh variables | grep <var-name> command can verify the variable exists. This is the simplest varification but you can also provide additional commands to test that the variable holds the desired value.

What is the level of urgency for publishing this change?

• Urgent - unblocks current or future work
• Slightly Less than Urgent

Tag your pair, your PM, and/or team!

@cloudfoundry/wg-app-runtime-deployments

It's helpful to tag a few other folks on your team or your team alias in case we need to follow up later.
@oliver-heinrich @iaftab-alam @jochenehret

[oliver-heinrich]

@stephanme: Can you also review this PR to add the cflinuxfs5 stack along with buildpacks as experimental opt-in as it affects cloud controller part.

[oliver-heinrich]

there are several lines of code starting with 'cnb'. Do you know if this is related to 'Cloud Native Buildpacks'. If yes then we should clarify with Stephan Merker and Jan von Loewenstein (his team provided cloud native buildpacks) if they are also supported/available for cflinuxfs5. If not that we should remove this code sections.