[RFC] Noble Based cflinuxfs5

[plamen-bardarov]

This PR adds the "Introduce cflinuxfs5 Stack Based on Ubuntu Noble (24.04)" RFC
Preview

[beyhan]

Hi @plamen-bardarov,

I would suggest to also add a Workstreams sections as e.g. available in https://github.com/cloudfoundry/community/blob/main/toc/rfc/rfc-0026-noble-os.md#workstreams. Additionally, I would suggest to have similar validation and maintenance requirements as for the Noble stemcell described in the App Runtime Deployments WG . I mean we should maintain the cflinuxfs4 and buildpacks based on that stack until the end of life of Jammy and have validations running in cf-deployment in parallel.

[rkoster]

How long will this transition period be?

[vpetrinski]

Hi @rkoster , thank you for the notice. I have changed the text. The goal is to support fs4 until Jammy reaches EOL.

[rkoster]

How will adoption be measured how do we know that production stability has been reached?

[vpetrinski]

The text is updated. Thank you.

[ChrisMcGowan]

Hi @plamen-bardarov,

For folks that will remain on Jammy based stemcells (example: FIPS requirements for OS), will cflinuxfs5 be a tested and a supported stack on Jammy stemcells ? If so can that be called out and added to this RFC along with a timeframe for that support ? Thanks

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: plamen-bardarov / name: Plamen Bardarov (a252f43, ac29d5c)
• ✅ login: vpetrinski (74c4184, 29cc9f0, db3f4d0, 116c87b, c1f988d, dbf70fd, 2ad4808, 64bf400, a873c7c)

[vpetrinski]

/easycla

[jochenehret]

As Beyhan mentioned above, we should have a dedicated Workstreams section for the App Runtime Deployments WG. The adoption of the new stack will require many steps (opt-in for fs5, make fs5 default, remove fs4 etc.). You can check the cflinuxfs4 issue as a reference.

@plamen-bardarov : Can you do that or should I add a section for the ARD WG?

[vpetrinski]

For folks that will remain on Jammy based stemcells (example: FIPS requirements for OS), will cflinuxfs5 be a tested and a supported stack on Jammy stemcells

Hi @ChrisMcGowan, This does not appear to be covered in the current RFC.
For those remaining on Jammy, cflinuxfs4 can continue to be used until its end-of-life.
Please note that we are aware of the request for FIPS compliance, and discussions are ongoing.
However, FIPS compliance is not addressed in this RFC.

[jochenehret]

ARD WG workstream proposal:

App Runtime Deployments WG

The ARD WG will integrate the cflinuxfs5 stack into the cf-deployment project and also validate the new stack. The steps will be similar to the cflinuxfs4 adoption (see cloudfoundry/cf-deployment#989):

1. Integrate cflinuxfs5-release into the "update-releases" pipeline to enable automatic version updates
2. Provide an experimental ops file to integrate cflinuxfs5 and the cflinuxfs5 buildpacks (as available)
3. Run CATs against a cflinuxfs5-enabled cf-deployment
4. Promote experimental ops file (or integrate directly into cf-deployment.yml)
5. Make cflinuxfs5 the default stack (-> major cf-d release)

The deprecation and removal of cflinuxfs4 will happen at a later time as that stack is being supported for now.

[ChrisMcGowan]

Hi @ChrisMcGowan, This does not appear to be covered in the current RFC. For those remaining on Jammy, cflinuxfs4 can continue to be used until its end-of-life. Please note that we are aware of the request for FIPS compliance, and discussions are ongoing. However, FIPS compliance is not addressed in this RFC.

@vpetrinski - Can you include in the RFC a support matrix of which stacks would be supported on which stemcells ? When cflinuxfs4 came out, it was still tested and supported on bionic stemcells while bionic was still under support.

I'm hoping this cross stemcell support this will continue with cflinuxfs5 for folks not moving to noble stemcells right away. This could be due to their use of FIPS ( jammy is almost certified - noble is in submittal phase ), older/customer BOSH releases not yet converted to work on noble, etc. If people are required to use noble stemcells in order to use cflinuxfs5, that will lead to those groups being "stuck" on older releases and missing out on new features/enhancements.

[beyhan]

Hi @ChrisMcGowan, This does not appear to be covered in the current RFC. For those remaining on Jammy, cflinuxfs4 can continue to be used until its end-of-life. Please note that we are aware of the request for FIPS compliance, and discussions are ongoing. However, FIPS compliance is not addressed in this RFC.

@vpetrinski - Can you include in the RFC a support matrix of which stacks would be supported on which stemcells ? When cflinuxfs4 came out, it was still tested and supported on bionic stemcells while bionic was still under support.

I'm hoping this cross stemcell support this will continue with cflinuxfs5 for folks not moving to noble stemcells right away. This could be due to their use of FIPS ( jammy is almost certified - noble is in submittal phase ), older/customer BOSH releases not yet converted to work on noble, etc. If people are required to use noble stemcells in order to use cflinuxfs5, that will lead to those groups being "stuck" on older releases and missing out on new features/enhancements.

I think it makes sense to validate the cflinuxfs4 and cflinuxfs5 on the supported stemcells Jammy and Noble. @jochenehret what is your input on this? Does it add a lot of complexity to the validation?

[jochenehret]

No, this won't be much effort to validate both stacks on both stemcells. We just have to configure the cflinuxfs5 ops file for the deployment and list the stacks in the CATs configuration.

[beyhan]

During the TOC meeting on 06.05.2025 we decided to start the FCP for this RFC with the goal to approve it.