Add process for SIG-Node collaboration

This adds public documentation of the process for containerd project
collaboration with Kubernetes SIG-Node.  It is mostly a formalization of
what we have already been doing informally, but the formalization should
help with visibility and work distribution.

Signed-off-by: Samuel Karp <[email protected]>

Author: samuelkarp

SIG-NODE.md

@@ -0,0 +1,148 @@
+# Collaboration with Kubernetes SIG-Node
+
+containerd is a popular container runtime used with
+[Kubernetes](https://kubernetes.io).  containerd implements the Kubernetes
+Container Runtime Interface (CRI) and is expected to participate in the
+development and implementation of CRI.
+
+Changes to Kubernetes (including CRI) are primarily driven through the
+[Kubernetes Enhancement Proposal (KEP) process](https://github.com/kubernetes/enhancements).
+KEPs are proposed to individual Special Interest Groups (SIGs) within the
+Kubernetes project, which help to refine, clarify, and decide the content of an
+individual KEP as well as drive its implementation.  CRI-related KEPs are
+primarily handled through SIG-Node.  SIG-Node has
+[adopted a policy](https://www.kubernetes.dev/docs/code/cri-api-dev-policies/)
+which requires KEPs to reach maturity in both containerd and CRI-O before
+advancing through graduation stages.
+
+This document describes the process that the containerd project uses to
+collaborate with SIG-Node on any KEP or other CRI-related change.
+
+## Goals
+
+* Provide visibility of SIG-Node integration work for containerd (including
+  KEPs) for:
+  * containerd maintainers and community members who are not directly involved
+    in SIG-Node
+  * SIG-Node participants who are not involved in the containerd community
+* Ensure containerd maintainers and communtiy members have adequate
+  opportunities to participate in design without requiring full context on
+  every SIG-Node KEP or who are not familiar with the KEP process
+* Ensure contributors understand the status of their proposed contributions
+* Spread the KEP tracking and review load among interested maintainers, and
+  enable at least two interested containerd maintainers per KEP or
+  Kubernetes-related work item in order to facilitate knowledge sharing
+
+## Non-goals
+
+* Change the development or release process of containerd.  See the
+  [contribution guidelines](CONTRIBUTING.md) and
+  [versioning and release](https://containerd.io/releases) page.
+* Guarantee KEP delivery, outside of providing feedback during KEP design,
+  guiding contributors through processes, and reviews.
+
+## Roles
+
+* SIG-Node member liaison - a containerd maintainer responsible for
+  facilitating communication between SIG-Node and the containerd project
+  regarding KEP status, targeted containerd releases, and any other integration
+  work or pain points.
+* KEP shepherd - for each KEP, at least one (preferably two) containerd
+  maintainer(s) responsible for helping a KEP move through the implementation
+  and release process in containerd.
+
+## Metadata
+
+* Per-KEP issue in the
+  [containerd/containerd](https://github.com/containerd/containerd) repository
+  for tracking KEPs that require CRI changes in the container
+  runtime or one of our other containerd subprojects.  (This includes
+  relatively minor changes, such as a runc update or checking containerd config
+  to align defaults with feature gate GAs.)
+* Labels within the containerd/containerd repository corresponding to
+  Kubernetes minor releases, applied to KEP tracking issues and PRs
+* Recording the assigned shepherd(s) on the KEP tracking issue
+
+## Process
+
+For a KEP to be reviewed and implemented in containerd:
+
+### Issue management
+
+* An issue should be created in the
+  [containerd/containerd repository](https://github.com/containerd/containerd)
+  tracking the individual KEP as soon as possible
+  * containerd KEP tracking issues may be opened by one of the KEP owners,
+    an interested maintainer, or by a group within SIG-Node that is managing
+    the KEP process
+  * This includes all KEPs for SIG-Node, whether they are in Draft or Approved
+    status.  The same issue should continue to track the KEP through each
+    stage, alpha(s), beta(s), and GA
+  * The new issue title should include both the KEP number and a short title or
+    description of the goal of the KEP
+* containerd maintainers will triage new KEP tracking issues as needed
+* KEP tracking issues should be added to a label for the Kubernetes release
+  cycle within the containerd/containerd repository during triage
+
+### SIG-Node Liaison
+
+At least one containerd maintainer will be responsible to liaise with SIG-Node
+for each Kubernetes release cycle.  The liaison role involves:
+
+* Tracking the status of each KEP both in containerd and the larger context in
+  Kubernetes (including the status of the KEP in kubelet and/or other
+  involved/dependent SIGs / projects).
+* Tracking the status of the other types of Node Integration pain points
+  critical to the upcoming kubernetes releases (likely via issue)
+* Communicating which containerd release(s) will include a given KEP (usually
+  the next minor release in our
+  [6-month release cadence](https://containerd.io/releases/#release-cadence))
+  and whether there are implications to prior containerd releases as KEPs are
+  promoted
+* Ensuring other types of SIG-Node integration pain points have at least one
+  containerd maintainer assigned. These include urgent Kubernetes PRs that
+  require containerd support and standard issues that don’t require a KEP, long
+  running infra tasks, major critest/crictl interop up on
+  kubernetes-sigs/critools, etc.
+* Being a
+  [Kubernetes org member](https://github.com/kubernetes/community/blob/master/community-membership.md#member)
+  and
+  [SIG-Node member](https://github.com/kubernetes/community/blob/master/sig-node/sig-node-contributor-ladder.md)
+  (prerequisite for volunteering)
+* Being available in the `#sig-node` channel of the [Kubernetes slack](https://slack.kubernetes.io)
+
+### KEP shepherd
+
+At least one containerd maintainer will be assigned (as part of KEP triage) to
+shepherd each active KEP planned for integration with containerd.  An active
+KEP is one which has already been implemented in an existing Kubernetes release
+or is being considered for an upcoming Kubernetes release.  The shepherd role
+involves:
+
+* Engaging as early as possible in the KEP discussion (via the primary KEP
+  issue, `#sig-node` Slack channel, and SIG-Node weekly calls) and design to
+  represent the containerd maintainer perspective in terms of
+  architecture/layering (i.e., should the new functionality reside in the
+  runtime, Kubelet, or some other component) and priority so that
+  implementation can be scheduled into an upcoming release.
+* Ensuring maintainers have consensus on how the KEP should be implemented in
+  containerd and communicating to the KEP owner and our liaison if consensus on
+  implementation details and/or timing cannot be reached in time for the next
+  minor release.
+* Ensuring the implementation design discussion happens in the open and
+  transparently; allowing proposals from the KEP owner, contributors, and
+  maintainers.
+* Coordinating contributors to implement the KEP
+* Coordinating the review and merge of containerd side KEP-related PRs
+  coinciding with required k/k CRI, kubelet, and other project dependencies
+  * Shepherds should provide initial review of the containerd PRs
+  * Shepherds should ensure that documentation for any new CRI API clearly
+    articulates any guarantees that containerd must provide and any API
+    behaviors that are not clear from the API declaration
+* Assist the liason(s) with reviews of the other KEP dependent PRs, such as CRI
+  API changes, Kubelet changes, etc.
+* Communicating the status of the KEP clearly on the tracking issue which will
+  be cross linked to the KEP issue document, PRs, and other SIG-Node tracking
+  documents.
+* The shepherd role is not necessarily responsible for designing or
+  implementing the KEP themselves