Summary of Cloud Native Buildpacks Summit

Matthew Gibson

Hello, mailing list readers!  

My name is Matt Gibson and I work as a PM on the Cloud Native Buildpacks project. Hopefully by this point you’ve visited, reviewed some of our documentation, and started to play around with the ‘pack’ CLI.  As always, we’re happy to answer questions, resolve issues, and listen to suggestions for how to improve @

While we're still excited about the beta release mentioned above, we also wanted to share an update about the CNB summit last month. On 3/20, core project contributors and platform stakeholders potentially seeking to integrate with CNBs gathered in Pivotal’s New York office to discuss future areas of focus for the project.  Others invited were maintainers of existing buildpack or buildpack-like integrations. During the meetings, the core project contributors solicited and prioritized feedback related to contributing to and using CNBs, the feasibility of various platform integrations, and to set up a more robust governance framework to better accommodate a growing community. We will review each of these areas in more detail below.  

Attendee List:

Scott Andrews (Project Riff)

**Emily Casey (Cloud Native Buildpacks)

Jacques Chester (formerly Cloud Native Buildpacks)

Daniella Corricelli (Cloud Foundry Windows)

Matt Gibson (Cloud Native Buildpacks)

*Joe Kutner (Cloud Native Buildpacks + Heroku)

Jose Gonzalez (Herokuish/Dokku)

*Ben Hale (Cloud Native Buildpacks + Cloud Foundry)

Daniel Joyce (Cloud Native Buildpacks)

Guillermo Kardolus (Cloud Foundry)

*Terence Lee (Cloud Native Buildpacks + Heroku)

*Stephen Levine (Cloud Native Buildpacks + Cloud Foundry)

Matt McNew (Cloud Native Buildpacks)

Andrew Meyer (Cloud Native Buildpacks)

Michelle Noorali (Draft + CNAB)

Joao Pereira (Cloud Native Buildpacks)

Ashwin Venkatesh (Cloud Native Buildpacks)

Micha Young (Cloud Foundry Windows)

* Project Owner

** Core Maintainer

Community Feedback

Collecting feedback from the community using and contributing to CNBs was a primary goal for the summit.  At various points, all attendees silently generated feedback on sticky notes, these notes were then affinity mapped based on the topic, and voted on by the group in an effort to prioritize the project’s focus.  UX, buildpack groups, and onboarding were the clear winners. To dig a little bit deeper on each of these categories, see below for some examples of the feedback we collected.


  • “When I get an error, it’s really difficult to know why”

  • “All the different metadata can be hard to keep track of”

  • “Unclear who is the primary user of pack CLI”

Buildpack Groups:

  • “Difficult to distribute buildpack groups”

  • “Buildpack groups can be complicated”

  • “Sharing groups is not well defined”


  • “How do I know which commands are meant for which persona?”

  • “Getting started documentation could be better”

  • “New to docker, the struggle is real”

We found this feedback extremely helpful, action items arising from this exercise have already influenced the work we’ve prioritized.  

  • Andrew Meyer (Pivotal) updated the read me in the CNB repo and created a new tutorial based around using CNBs to create an image from a simple Java app and running it on a cloud platform

  • We recently added a UX designer to the team who will focus on improving the pack CLI.  Additionally, the CNB team pulled more stories around improving the UX into the Beta release including - limiting the amount of generated image shas, making `pack inspect builder` more helpful, and more gracefully handling exiting a command when an image is pulling.

  • Incoming PR that modifies the specification to improve the buildpack groups experience

Platform Integrations

In addition to collecting feedback, we wanted to take the opportunity presented by gathering in person to work through potential platform integrations.  Representatives from Draft, Dokku, and the Cloud Foundry Windows .NET experience team paired with at least one core CNB project contributor to work through a technical implementation for each platform.  Here’s a snapshot of some of the things we learned:

  • Fewer barriers than anticipated to integrate CNBs with the Draft platform

  • Pack as a library would probably help platforms come up with integration strategies more easily

  • Mixins would be a huge help for Dokku and we should probably prioritize them following release of the CNB Beta


In 2019 we aim to grow the community by pursuing new platform integrations and adding more contributors and maintainers from a more diverse range of companies.  As we seek to add new voices, it is important to establish a more robust and well documented governance framework. Michelle Noorali of the Microsoft Draft team provided a lot of helpful feedback and shared insight into how more mature CNCF projects structure their governance.  Terence Lee captured the updates to our governance in a write-up, feel free to check it out and leave feedback!  

Thanks for reading!  Stay tuned for further updates.


The Cloud Native Buildpacks Team

A message from the Buildpacks' Owl

Joe Kutner

Hello from the Cloud Native Buildpacks team,

We’d like to share a few updates on the project, and set some expectations for how we’ll be using this mailing list.

The recently discussed an RFC in which we resolve to use the mailing list more often. We’ve heard from the community that Slack is not always the best place to share information and have discussions. As a result, we plan to distribute (at a minimum) the following updates via email as a matter of policy:

• RFCs entering Final Comment Period
• New releases, including (but not limited to) lifecycle and pack
• Changes to governance structure, core team, maintainers, etc

There will be other topics for sure, and anyone can use the mailing list to ask questions, share ideas, or shower us with praise :)

We’ll continue to use Slack and we encourage everyone who can to join the conversation there. But don’t hesitate to reach out to us on the mailing list.

The CNB team

New Platform Maintainer

Joe Kutner

The Buildpacks team would like to welcome Javier Romero as an official Platform Maintainer. Javier has been contributing to the Pack CLI since May 2019 and will now take on leadership responsibilities for the project, which include change approval and maintence. Congrats Javier, and thank you for your work.

RFC: Pack Build Default Process Flag

Joe Kutner

RFC "Pack Build Default Process Flag" has entered Final Comment Period. This will be open until next Thursday (Dec 12, 2019) at which time it will be merged and accepted at the WG meeting.

Renaming of Github org

Joe Kutner

We've renamed our Github org from "buildpack" to "buildpacks":

Please let us know if you encounter any issues.

[RFC] Minimal Project Descriptor

Joe Kutner

RFC "Minimal Project Descriptor" has entered Final Comment Period. This will be open until next Thursday (Jan 16, 2020) at which time it will be merged and accepted at the WG meeting.

[RFC] Lifecycle Compatibility Verification

Joe Kutner

RFC "Lifecycle Compatibility Verification" has entered Final Comment Period. This will be open until next Thursday (Jan 16, 2020) at which time it will be merged and accepted at the WG meeting.

Breaking Change Notice: Lifecycle 0.6.0



The Cloud Native Buildpacks team is scheduled to release a new version of the lifecycle. The release contains some changes we want to make the community aware of in advance.


The next release of the lifecycle (0.6.0) contains changes which improve caching performance. These improvements introduce some breaking changes between the lifecycle and previous platform APIs. 

Builders containing the 0.5.0 version of the lifecycle will continue to work with newer versions of pack. This is the default version (as of pack 0.6.0) injected during the builder creation process. 

Explicit configuration of the lifecycle.version field to 0.5.0 during builder creation will allow you take the time to update to the latest changes. We plan to update the default version of the lifecycle to 0.6.0 at a later release of pack.

In order to maintain platform compatibility, platforms will need to implement the changes noted below.


There are 3 major changes that impact backwards compatibility.

  1. `cacher` is now part of `exporter`. (#205)

    • Impact: Major

    • The `cacher` binary is no longer present. Refer to RFC#14 for details.

  2. `analyzer` and `restorer` order of operations swap. (#207)

    • Impact: Major

    • The order in which `analyzer` and `restorer` are executed must be inverted. Refer to RFC#14 for details.

  3. Implementation of App Slices as detailed in spec. (#210, #220)

    • Impact: Minor

    • A key on a metadata label used by the lifecycle has changed from a string to an array to align with the fact that there are now multiple application layers due to slices.



Due to these breaking changes the Platform API version is being updated to 0.2. Platforms that support arbitrary builders should attempt to support both Platform API versions 0.1 and 0.2 for a transitional period. Platform authors can do this by supporting both the old and new build sequences/binaries, and selecting the proper sequence based on the lifecycle's declared API version. A platform can read a given lifecycle's declared platform API version by inspecting the io.buildpacks.builder.metadata label on a builder (lifecycle.api.platform field).


pack 0.6.0 was updated (#384, #415, #423) to support both Platform API 0.1 and 0.2.

There is a minor constraint brought upon by the App Slices changes:

  • pack 0.6.0 can rebase app images from lifecycle greater than or equal to 0.5.0

  • pack 0.5.0 cannot rebase app images from lifecycle 0.6.0


The tekton task will be updated to support only Platform API 0.2 in the coming weeks. (#176)


There is no impact on buildpacks.


Since builders have an embedded lifecycle with a specific supported Platform API version, if the platform in which these builders are used does not support their provided Platform API version errors are expected. Builders can be created with an explicit Lifecycle version, which allows you to pin to a version of the lifecycle if your platform does not yet support the newest lifecycle. This is documented here.

For any questions or concerns please reach out via mailing list or slack.

New Learning Maintainer

Joe Kutner

The Buildpacks team would like to welcome Javier Romero as a Learning Maintainer. Javier is already a Platform Maintainer, but will now also help with maintenance of our Learning repositories. For more information on the Learning team and the project's governance, please see our Community Github Repo:

Platform API 0.3

Javier Romero <jromero@...>


New platform API 0.3 will be available after the release of lifecycle 0.7.0.

Platform API 0.3 comes with the following changes:

  1. Added support for project-metadata.toml. (#230)

  2. Added support for /lifecycle/creator. (#243)

  3. Added support for -process-type flag. (#260)

  4. [Breaking] Removal of the -helpers flag. (#259)


In general, platforms should ensure that they support the stated changes to be compliant with Platform API 0.3.


An update to the Tekton task will be available per issue #194.


Added support for Platform API 0.3

pack will be compatible with Platform API 0.3 although it will not yet take advantage of all the new features. (#509)

Dropping support of Platform API 0.1

The platform team aims to always provide support for n-1 of the platform API and buildpack API versions. Given that a new platform API version (0.3) is available, we found it reasonable to drop support for platform API 0.1. (#509)

For more detail on what the changes are between platform API 0.1 and 0.2 please refer to the prior notice.


No impact to builders is expected.


No impact to buildpacks is expected.

[newsletter] April 2020

Joe Kutner

Hello Buildpacks community. We’d like to share some updates from the past month.  



  • Finalized RFC-0029: Buildpack homepage

  • Finalized RFC-0030: RFC template changes

  • Finalized RFC-0031: Defining Mixins for io.buildpacks.stacks.bionic

  • Final Comment Period for PR #66: Update JSON schema in CNB Registry



Please reach out to us if there’s something you’d like us to include in next month’s newsletter.

Welcome Emily Casey to the Core Team

Joe Kutner

The Cloud Native Buildpacks project would like to welcome Emily Casey to the CNB core team.

Emily has worked on the project since its inception, and is a maintainer on both the Platform and Implementation teams. She is the top committer to both the Pack CLI and the CNB Lifecycle with more than 460,000 lines of code contributed. You can find Emily on Twitter[1] and LinkedIn[2].

Thank you for all the work you've done Emily, and welcome to the team.


[newsletter] May 2020

Joe Kutner

Hello Buildpacks community. We’d like to share some updates from the past month.  



  • Paketo Buildpacks, which are implementations of the CNB spec, were launched by the Cloud Foundry Project. Learn more at
  • There’s a new Tilt Extension for Pack. Tilt manages local development instances for teams that deploy to Kubernetes.


Request for End-Users

Joe Kutner

Hello Community,

We're in the process of becoming a CNCF Incubating project. As part of this, we need to create a list of users. We've listed plenty of platforms integrating the CNB lifecycle, but we're now looking for end-users.

If you're a person or company that either builds applications with buildpacks or creates buildpacks using the specification and would like to be listed in the TOC due diligence docs (we won't advertise your usage beyond this document without your consent) please reach out. 

You can email me directly, DM me on Slack, or open a PR against 

The CNB team

[newsletter] June 2020

Joe Kutner

Hello Buildpacks community. Last month was busy, and we’ve got a lot to share!





Primary branch name changed to "main" for all repos

Joe Kutner

As part of our commitment to being an inclusive and welcoming community, we've renamed the primary branch on all repos to "main".

Our Homebrew tap for Pack should continue to work. But if you're experiencing problems, please retap by running:

$ brew untap buildpacks/tap
$ brew tap buildpacks/tap
$ brew upgrade pack

Please let us know if you encounter any other issues.

The CNB team

[newsletter] July 2020

Joe Kutner

Hello Buildpacks community. We’d like to share some updates from the past month.  






[newsletter] August 2020

Joe Kutner

Hello Buildpacks community. We'd like to share some updates from the past month.  





Welcome Yael Harel to the Implementation Team

Joe Kutner

Congratulations to Yael Harel, our newest Implementation Team contributor! Thank you Yael for your substantive contributions to the lifecycle and your thoughtful feedback on recent changes to the specification. We are excited to have you on the team.

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