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Contributing to Kubeflow
Welcome to the Kubeflow project!
Getting started as a Kubeflow contributor
This document is the single source of truth for how to contribute to the code base. We’d love to accept your patches and contributions to this project. There are just a few small guidelines you need to follow.
Sign the CLA
Contributions to this project must be accompanied by a Contributor License Agreement (CLA). You (or your employer) retain the copyright to your contribution. This gives us permission to use and redistribute your contributions as part of the project. Head over to https://cla.developers.google.com/ to see your current agreements on file or to sign a new one.
You generally only need to submit a CLA once, so if you’ve already submitted one (even if it was for a different project), you probably don’t need to do it again.
Follow the code of conduct
Please make sure to read and observe our Code of Conduct.
Consider participating in Kubeflow user research
Maggie Lynn, a user experience researcher, is conducting user studies to inform future developments for Kubeflow. These typically involve a one hour study session conducted online with a thank you gift for providing your feedback. As a member of the Kubeflow community, your feedback and expertise are extremely valuable to us, so if you have time in the next month, please consider participating. To gather your interest, availability, and some basic information about you, please fill out this form where you’ll find out more details about this research opportunity: https://goo.gl/forms/sv5sRo3UfsgeUEjK2
Joining the community
Follow these instructions if you want to
- Become a member of the Kubeflow GitHub org (see below)
- Become part of the Kubeflow build cop or release teams
- Be recognized as an individual or organization contributing to Kubeflow
Joining the Kubeflow GitHub Org
Before asking to join the community, we ask that you first make a small number of contributions to demonstrate your intent to continue contributing to Kubeflow.
There are are a number of ways to contribute to Kubeflow
- Submit PRs
- File issues reporting bugs or providing feedback
- Answer questions on Slack or GitHub issues
You can use this table to see how many contributions you’ve made
- Note: This only counts GitHub related ways of contributing
When you are ready to join
- Send a PR adding yourself as a member in org.yaml
- After the PR is merged an admin will send you an invitation
- This is a manual process that’s generally run a couple times a week
- If a week passes without receiving an invitation reach out on kubeflow#community
If you would like your company or organization to be acknowledged for contributing to Kubeflow or participating in the community (being a user counts) please send a PR adding the relevant info to member_organizations.yaml.
If you want your employee’s GitHub contributions to be attributed to your company please ask them to set the company field in their GitHub profile.
There are many ways to contribute! Join one of our communication channels, attend a community meeting, get to know the community. Read the details in our community guide.
Your first contribution
Find something to work on
Help is always welcome! For example, documentation (like the text you are reading now) can always use improvement. There’s always code that can be clarified and variables or functions that can be renamed or commented. There’s always a need for more test coverage. You get the idea - if you ever see something you think should be fixed, you should own it. Here is how you get started.
To find Kubeflow issues that make good entry points:
- Start with issues labeled good first issue. For example, see the good first issues in the kubeflow/website repository for doc updates, and in the kubeflow/kubeflow repository for updates to the core Kubeflow code.
- For issues that require deeper knowledge of one or more technical aspects, look at issues labeled help wanted. For example, see these issues in the kubeflow/kubeflow repository
- Examine the issues in any of the Kubeflow repositories.
Owners files and PR workflow
Overview of OWNERS files
OWNERS files are used to designate responsibility over different parts of the Kubeflow codebase. Today, we use them to assign the reviewer and approver roles used in our two-phase code review process. Our OWNERS files were inspired by Chromium OWNERS files, which in turn inspired GitHub’s CODEOWNERS files.
The velocity of a project that uses code review is limited by the number of people capable of reviewing code. The quality of a person’s code review is limited by their familiarity with the code under review. Our goal is to address both of these concerns through the prudent use and maintenance of OWNERS files
Each directory that contains a unit of independent code or content may also contain an OWNERS file. This file applies to everything within the directory, including the OWNERS file itself, sibling files, and child directories.
OWNERS files are in YAML format and support the following keys:
approvers: a list of GitHub usernames or aliases that can
labels: a list of GitHub labels to automatically apply to a PR
options: a map of options for how to interpret this OWNERS file, currently only one:
no_parent_owners: defaults to
falseif not present; if
true, exclude parent OWNERS files. Allows the use case where
a/OWNERSfile from having any effect on
reviewers: a list of GitHub usernames or aliases that are good candidates to
All users are expected to be assignable. In GitHub terms, this means they are either collaborators of the repo, or members of the organization to which the repo belongs.
A typical OWNERS file looks like:
approvers: - alice - bob # this is a comment reviewers: - alice - carol # this is another comment - sig-foo # this is an alias
Each repo may contain at its root an OWNERS_ALIAS file.
OWNERS_ALIAS files are in YAML format and support the following keys:
aliases: a mapping of alias name to a list of GitHub usernames
We use aliases for groups instead of GitHub Teams, because changes to GitHub Teams are not publicly auditable.
A sample OWNERS_ALIASES file looks like:
aliases: sig-foo: - david - erin sig-bar: - bob - frank
GitHub usernames and aliases listed in OWNERS files are case-insensitive.
The code review process
- The author submits a PR
- Phase 0: Automation suggests reviewers and approvers for the PR
- Determine the set of OWNERS files nearest to the code being changed
- Choose at least two suggested reviewers, trying to find a unique reviewer for every leaf OWNERS file, and request their reviews on the PR
- Choose suggested approvers, one from each OWNERS file, and list them in a comment on the PR
- Phase 1: Humans review the PR
- Reviewers look for general code quality, correctness, sane software engineering, style, etc.
- Anyone in the organization can act as a reviewer with the exception of the individual who opened the PR
- If the code changes look good to them, a reviewer types
/lgtmin a PR comment or review; if they change their mind, they
- Once a reviewer has
/lgtm‘ed, prow (@k8s-ci-robot) applies an
lgtmlabel to the PR
- Phase 2: Humans approve the PR
- The PR author
/assign’s all suggested approvers to the PR, and optionally notifies them (eg: “pinging @foo for approval”)
- Only people listed in the relevant OWNERS files, either directly or through an alias, can act as approvers, including the individual who opened the PR
- Approvers look for holistic acceptance criteria, including dependencies with other features, forwards/backwards compatibility, API and flag definitions, etc
- If the code changes look good to them, an approver types
/approvein a PR comment or review; if they change their mind, they
- prow (@k8s-ci-robot) updates its comment in the PR to indicate which approvers still need to approve
- Once all approvers (one from each of the previously identified OWNERS files) have approved,
prow (@k8s-ci-robot) applies an
- The PR author
Phase 3: Automation merges the PR:
If all of the following are true:
- All required labels are present (eg:
- Any blocking labels are missing (eg: there is no
- All required labels are present (eg:
And if any of the following are true:
- there are no presubmit prow jobs configured for this repo
- there are presubmit prow jobs configured for this repo, and they all pass after automatically being re-run one last time
Then the PR will automatically be merged
Quirks of the process
There are a number of behaviors we’ve observed that while possible are discouraged, as they go against the intent of this review process. Some of these could be prevented in the future, but this is the state of today.
- An approver’s
/lgtmis simultaneously interpreted as an
- While a convenient shortcut for some, it can be surprising that the same command is interpreted in one of two ways depending on who the commenter is
- Instead, explicitly write out
/approveto help observers, or save the
/lgtmfor a reviewer
- This goes against the idea of having at least two sets of eyes on a PR, and may be a sign that there are too few reviewers (who aren’t also approver)
- Technically, anyone who is a member of the Kubeflow GitHub organization can drive-by
- Drive-by reviews from non-members are encouraged as a way of demonstrating experience and intent to become a collaborator or reviewer
/lgtm’s from members may be a sign that our OWNERS files are too small, or that the existing reviewers are too unresponsive
- This goes against the idea of specifying reviewers in the first place, to ensure that author is getting actionable feedback from people knowledgeable with the code
- Reviewers, and approvers are unresponsive
- This causes a lot of frustration for authors who often have little visibility into why their PR is being ignored
- Many reviewers and approvers are so overloaded by GitHub notifications that @mention’ing is unlikely to get a quick response
- If an author
/assign’s a PR, reviewers and approvers will be made aware of it on their PR dashboard
- An author can work around this by manually reading the relevant OWNERS files,
/unassign‘ing unresponsive individuals, and
- This is a sign that our OWNERS files are stale; pruning the reviewers and approvers lists would help with this
- Authors are unresponsive
- This costs a tremendous amount of attention as context for an individual PR is lost over time
- This hurts the project in general as its general noise level increases over time
- Instead, close PR’s that are untouched after too long (we currently have a bot do this after 90 days)
Automation using OWNERS files
Prow receives events from GitHub, and reacts to them. It is effectively stateless. The following pieces of prow are used to implement the code review process above.
- cmd: tide
- per-repo configuration:
labels: list of labels required to be present for merge (eg:
missingLabels: list of labels required to be missing for merge (eg:
reviewApprovedRequired: defaults to
false; when true, require that there must be at least one approved pull request review present for merge
merge_method: defaults to
rebase, use that merge method instead when clicking a PR’s merge button
- merges PR’s once they meet the appropriate criteria as configured above
- if there are any presubmit prow jobs for the repo the PR is against, they will be re-run one final time just prior to merge
- plugin: assign
- assigns GitHub users in response to
/assigncomments on a PR
- unassigns GitHub users in response to
/unassigncomments on a PR
- assigns GitHub users in response to
- plugin: approve
- per-repo configuration:
issue_required: defaults to
true, require that the PR description link to an issue, or that at least one approver issues a
implicit_self_approve: defaults to
true, if the PR author is in relevant OWNERS files, act as if they have implicitly
- adds the
approvedlabel once an approver for each of the required OWNERS files has
- comments as required OWNERS files are satisfied
- removes outdated approval status comments
- plugin: blunderbuss
- determines reviewers and requests their reviews on PR’s
- plugin: lgtm
- adds the
lgtmlabel when a reviewer comments
/lgtmon a PR
- the PR author may not
/lgtmtheir own PR
- adds the
- pkg: k8s.io/test-infra/prow/repoowners
- parses OWNERS and OWNERS_ALIAS files
- if the
no_parent_ownersoption is encountered, parent owners are excluded from having any influence over files adjacent to or underneath of the current OWNERS file
Maintaining OWNERS files
OWNERS files should be regularly maintained.
We encourage people to self-nominate or self-remove from OWNERS files via PR’s. Ideally in the future we could use metrics-driven automation to assist in this process.
We should strive to:
- grow the number of OWNERS files
- add new people to OWNERS files
- ensure OWNERS files only contain org members and repo collaborators
- ensure OWNERS files only contain people are actively contributing to or reviewing the code they own
- remove inactive people from OWNERS files
Bad examples of OWNERS usage:
- directories that lack OWNERS files, resulting in too many hitting root OWNERS
- OWNERS files that have a single person as both approver and reviewer
- OWNERS files that haven’t been touched in over 6 months
- OWNERS files that have non-collaborators present
Good examples of OWNERS usage:
- there are more
approversare not in the
- OWNERS files that are regularly updated (at least once per release)
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