feat: Addition of Reviewer's Guideline (#4338)

2 files changed, 277 insertions, 7 deletions

diff --git a/contributors/guide/collab.md b/contributors/guide/collab.md
index 6f3b95fa..4c80ff88 100644
--- a/contributors/guide/collab.md
+++ b/contributors/guide/collab.md
@@ -30,10 +30,3 @@ changes.
 
 Expect reviewers to request that you avoid [common go style
 mistakes](https://github.com/golang/go/wiki/CodeReviewComments) in your PRs.
-
-## Assigned reviews
-
-Maintainers can assign reviews to other maintainers, when appropriate. The
-assignee becomes the shepherd for that PR and is responsible for merging the PR
-once they are satisfied with it or else closing it. The assignee might request
-reviews from non-maintainers.
diff --git a/contributors/guide/review-guidelines.md b/contributors/guide/review-guidelines.md
new file mode 100644
index 00000000..4526e177
--- /dev/null
+++ b/contributors/guide/review-guidelines.md
@@ -0,0 +1,277 @@
+---
+title: "Pull Request Review Guidelines"
+weight: 13
+slug: "review-guidelines"
+---
+- [Tips for getting your PR reviewed](#tips-for-getting-your-pr-reviewed)
+  - [Use Tokens to signal the state of your PR](#use-tokens-to-signal-the-state-of-your-pr)
+  - [Reduce the scope of your PR](#reduce-the-scope-of-your-pr)
+  - [Split your PR into logical smaller commits](#split-your-pr-into-logical-smaller-commits)
+  - [Squash or remove unnecessary commits](#squash-or-remove-unnecessary-commits)
+  - [Explain your changes (comments)](#explain-your-changes-comments)
+  - [Ensure you properly test your changes](#ensure-you-properly-test-your-changes)
+  - [Commit messages should be thorough and detailed](#commit-messages-should-be-thorough-and-detailed)
+  - [Pull Request comments should summarize the PR](#pull-request-comments-should-summarize-the-pr)
+  - [Minor changes (typos / link fixes)](#minor-changes-typos--link-fixes)
+- [Tips for code reviewers](#tips-for-code-reviewers)
+  - [Managing time](#managing-time)
+    - [Block time off to review](#block-time-off-to-review)
+    - [Taking a break or stepping away](#taking-a-break-or-stepping-away)
+  - [Loop in others when domain specific knowledge is needed](#loop-in-others-when-domain-specific-knowledge-is-needed)
+  - [Asking questions](#asking-questions)
+  - [Asking for changes](#asking-for-changes)
+    - [Commit Hygiene](#commit-hygiene)
+  - [Be clear on progress and time](#be-clear-on-progress-and-time)
+  - [Checking out a PR](#checking-out-a-pr)
+- [Additional Resources](#additional-resources)
+
+
+## Tips for getting your PR reviewed
+
+
+### Use Tokens to signal the state of your PR
+
+Token phrases like `WIP` or `do not merge` signal to reviewers that the PR is
+potentially in a state that is not complete. This can save significant time for
+reviewers on prioritizing which PR should be reviewed. They can either hold off
+on reviewing altogether or will review the PR with the knowledge that it is not
+complete.
+
+
+### Reduce the scope of your PR
+
+Extremely large PRs take significant amounts of time to both review and evaluate
+for potential upstream/downstream impacts. If it is possible to achieve the
+desired goal over multiple smaller, more concise PR ("Pre-factor"), it decreases
+risk and will have a greater chance of being accepted.
+
+
+### Split your PR into logical smaller commits
+
+Multiple smaller commits that contain the logical pieces of work simplify the
+review process for others to review your code. These commits should be able to
+stand on their own and not necessarily depend on other things.
+
+**Example: Markdown**
+
+A PR that applies both formatting changes and content changes. If taken together
+in a single commit, it will appear to your reviewer that the entire document has
+changed and will require more time to compare and separate the actual content
+changes from the style changes.
+
+If content and style changes were made in separate commits, they could be reviewed
+independently for their changes.
+
+**Example: Generated code**
+
+A PR that has both authored code and generated code can be difficult to parse.
+If the authored code and generated code are in separate commits, the generated
+code can largely be ignored by the reviewer, and they can focus their time on
+the authored code.
+
+### Squash or remove unnecessary commits
+
+Often you may rapidly commit small changes or fixes. These are even more common
+when accepting suggestions through the GitHub UI where each change is done as an
+independent small commit. [Squashing] these down into a logical commit will both
+help your reviewer when performing a final pass, and provide for a clean git
+commit history.
+
+
+### Explain your changes (comments)
+
+Comments should be used for **ANY** non-obvious changes. They should explain why
+something was done and the intent behind it; leave no surprises for the next
+person to view or touch your code. If you spent time debugging, testing, or 
+searching for prior art on a means to do something - document it in the comments.
+
+If you leave a `TODO`, it should explain why it needs to be revisited along with
+any relevant information that could help the next person looking to update that
+part of the code. Consider following insertion of a `TODO` with creating a new
+_help wanted_ issue, if appropriate.
+
+This is also true for things that should **NOT** be updated or updated with great
+care. It should document why it cannot be further reduced or changed. For an
+example of this, see the _"[KEEP THE SPACE SHUTTLE FLYING]"_ portion of the
+persistent volume controller as an example.
+
+
+### Ensure you properly test your changes
+
+Code submitted without tests will almost always be rejected at first pass. If an
+area you're updating did not previously have them, adding them in your PR will
+be appreciated and helps improve the overall health of the project.
+
+If something you change has the potential to impact the performance or scalability
+of the project, include a benchmark. These are essential to demonstrate the 
+efficacy of your change and will help in preventing potential regressions.
+
+
+### Commit messages should be thorough and detailed
+
+PR comments are not represented in the commit history. Important details
+regarding your changes should be kept in your commit message.
+
+The commit message subject line should be no more than 72 characters and
+summarize the changes being made.
+
+Use the body of the commit message to describe **WHY** the change is being made.
+Describing why something has changed is more important than how. You are
+providing context to both your reviewer and the next person that has to touch
+your code.
+
+For more guidance on commit messages, see our [commit message guidelines].
+
+
+### Pull Request comments should summarize the PR
+
+The GitHub pull request should contain a summary of the changes being made as
+well as links to all the relevant information related to the PR itself. These
+are things such as issues it closes, KEPs, and any other relevant documentation.
+
+Accurately filling out the issue template and applying the necessary labels
+will greatly speed up the initial triage of your PR.
+
+If there is a portion of your PR that should be explained or linked that is not
+committed as a comment, you can review your own PR, applying additional context
+or links.
+
+
+### Minor changes (typos / link fixes)
+
+While these sort of fixes are appreciated, try and fix multiple instances at the
+same time if possible, instead of issuing subsequent individual PRs for each fix.
+
+---
+
+## Tips for code reviewers
+
+### Managing time
+
+#### Block time off to review
+
+Often it can be hard to find dedicated, uninterrupted time to review PRs. If you
+can, allocate some time and block it off on your calendar to help stay on top of
+the incoming queue.
+
+#### Taking a break or stepping away
+
+If you are taking a break, going on vacation, or stepping away for a bit -- you
+can set your [GitHub status] to busy; this will signal [Blunderbuss] to not
+automatically assign you to reviews (It does not block manual assignment).
+
+If for an extended period of time, or if you need to focus on other areas,
+consider setting yourself as an `[emeritus_approver]` in some of the areas your
+an approver.
+
+
+### Loop in others when domain specific knowledge is needed
+
+Kubernetes has an incredibly large and complex code base with sections that may
+require domain-specific knowledge. If you are unsure or uncomfortable reviewing
+a portion of a PR, it is better to decline a review and reassign to an owner or 
+contributor with more expertise in that area.
+
+If you are brought in for your knowledge in a specific area, try and provide
+meaningful comments to serve as breadcrumbs in the future to help others gain a
+better understanding of that area.
+
+
+### Asking questions
+
+You are encouraged to ask questions and seek an understanding of what the PR is
+doing; however, your question might be answered further into the review. You can
+stage your questions, and before you submit your review, revisit your own comments
+to see if they're still relevant or update them after gaining further context. 
+
+Often a question may turn into a request for further comments or changes to
+explain what is happening at that specific point.
+
+In your questions, try and be empathetic when phrasing. Instead of:
+
+_"Why did you do this?"_
+
+try
+
+_"Am I understanding this correctly? Can you explain why...?"_
+
+Remember a review is a discussion, often with multiple parties -- be reasonable.
+Try to focus and summarize in ways which constructively move the conversation
+forward instead of retreading ground.
+
+### Asking for changes
+
+It's okay to ask for changes to be made on a PR. In your comments, you should be
+clear on what is a 'nit' or small thing to be improved and a **required** change
+needed to accept the PR.
+
+Be clear and state upfront architectural or larger changes. These should be
+resolved first before addressing any further nits.
+
+It's also okay to say _"No"_ to a PR. As a community, we want to respect people's
+time and efforts, but sometimes things just don't make sense to accept. As
+reviewers, you are the stewards of the code-base and sometimes that means pushing
+back on potential changes.
+
+
+#### Commit Hygiene 
+
+It can be seen as trivial, but you can ask the PR author to break apart their
+PR into smaller chunks, or change a commit message to be more informative. They
+are the _"permanent record"_ of the change and should accurately describe both
+what and why it is being done.
+
+
+### Be clear on progress and time
+
+Be upfront with the PR author about where the state of their PR is and what
+needs to be completed for it to be accepted.
+
+No one likes it if their PR misses a release, but it is a fact of life. Try and
+be upfront about it. Don't push a PR through out of guilt or deadlines. Remember,
+you are a steward of the codebase.
+
+
+### Checking out a PR
+
+If a PR is too complex to review through the GitHub UI, you can pull it down
+locally to evaluate. You can do so using the following command:
+
+```
+git fetch origin pull/<PR ID>/head:<BRANCHNAME>
+git checkout <BRANCHNAME>
+```
+
+**Example:**
+```
+git fetch upstream pull/1245/head:foo
+git checkout foo
+```
+
+
+## Additional Resources
+
+- [Keeping the Bar High - How to be a bad ass Code Reviewer, Tim Hockin] - A
+  presentation by Tim from the Kubernetes Contributor Summit in San Diego. It is
+  largely what this document is based off of.
+- [Kubernetes Code Reviewing with Tim Hockin] - Some notes and tips from Tim on
+  how to effective at reviewing Kubernetes Code.
+- [Live API Review, Jordan Liggitt] - A presentation by Jordan from the Kubernetes
+  Contributor Summit in San Diego covering the sort of things they look for when
+  performing an API review for a new feature.
+- [The Gentle Art of Patch Review, Sage Sharp] - A blog post from Sage Sharp on
+  some methods of approaching PR review
+
+
+
+[squashing]: ./github-workflow.md#squash-commits
+[KEEP THE SPACE SHUTTLE FLYING]: https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/volume/persistentvolume/pv_controller.go#L57-L117
+[commit message guidelines]: ./pull-requests.md#7-commit-message-guidelines
+[GitHub Status]: https://help.github.com/en/github/setting-up-and-managing-your-github-profile/personalizing-your-profile#setting-a-status
+[Blunderbuss]: https://git.k8s.io/test-infra/prow/plugins/approve/approvers/README.md#blunderbuss-and-reviewers
+[emeritus_approver]: ./owners.md#emeritus
+[Keeping the Bar High - How to be a bad ass Code Reviewer, Tim Hockin]: https://www.youtube.com/watch?v=OZVv7-o8i40
+[Kubernetes Code Reviewing with Tim Hockin]: https://docs.google.com/document/d/15y8nIgWMzptHcYIeqf4vLJPttE3Fj_ht4I6Nj4ghDLA/edit#heading=h.3dchnigrxf5y
+[Live API Review, Jordan Liggitt]: https://www.youtube.com/watch?v=faRARV3C7Fk
+[The Gentle Art of Patch Review, Sage Sharp]: https://sage.thesharps.us/2014/09/01/the-gentle-art-of-patch-review/
+