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title authors reviewers approvers creation-date last-updated status see-also
Neat-Enhancement-Idea
@estroz
TBD
@joelanford
@dmesser
TBD
@joelanford
@dmesser
2019-09-12
2019-09-12
implementable
./cli-ux-phase1.md

sdk integration with olm

Release Signoff Checklist

  • Enhancement is implementable
  • Design details are appropriately documented from clear requirements
  • Test plan is defined
  • Graduation criteria for dev preview, tech preview, GA
  • User-facing documentation is created in openshift/docs

Summary

The Operator Lifecycle Manager (OLM) is a set of cluster resources that manage the lifecycle of an Operator. OLM can be installed onto a Kubernetes cluster to provide a robust Operator management system for any cluster users. The Operator SDK (SDK) should be able to interact with OLM to a degree that gives any user the ability to deploy their Operator and tear it down using OLM, all in a reproducible fashion. This proposal aims to describe integration of OLM into the SDK for deployment and teardown.

Motivation

OLM is an incredibly useful cluster management tool. There is currently no integration between SDK and OLM that encourages running an Operator with the latter.

Goals

General

  • Operator developers can use operator-sdk to quickly deploy OLM on a given Kubernetes cluster
  • Operator developers can use operator-sdk to run their Operator under OLM
  • Operator developers can use operator-sdk to build a catalog/bundle containing their Operator for use with OLM

Specific

  • operator-sdk creates a bundle from an Operator project to deploy with OLM
  • operator-sdk has a CLI interface to interact with OLM
  • operator-sdk installs a specific version of OLM onto Kubernetes cluster
  • operator-sdk uninstalls a specific version of OLM onto Kubernetes cluster
  • operator-sdk accepts a bundle and deploys that operator onto an OLM-enabled Kubernetes cluster
  • operator-sdk accepts a bundle and removes that operator onto an OLM-enabled Kubernetes cluster

Non-Goals

Proposal

User Stories

TODO

Detail the things that people will be able to do if this is implemented. Include as much detail as possible so that people can understand the "how" of the system. The goal here is to make this feel real for users without getting bogged down.

Story 1

Implementation Details/Notes/Constraints

Initial PR: operator-framework#1912

Use of operator-registry

The SDK's approach to deployment should be as general and reliant on existing mechanisms as possible. To that end, operator-registry should be used since it defines what a bundle contains and how one is structured. operator-registry libraries should be used to create and serve bundles, and interact with package manifests.

The idea is to create a Deployment containing the latest operator-registry image to initialize a bundle database and run a registry server serving that database using binaries contained in the image. The Deployment will contain volume mounts from a ConfigMap containing bundle files and a package manifest for an operator. Using manifest data in the ConfigMap volume source, the registry initializer can build a local database and serve that database through the Service. OLM-specific resources created by the SDK or supplied by a user, described below, will establish communication between this registry server and OLM.

OLM resources

OLM understands operator-registry servers and served data through several objects. A CatalogSource specifies how to communicate with a registry server. A Subscription links a particular CSV channel to a CatalogSource, indicating from which CatalogSource OLM should pull an Operator. Another OLM resource that may be required is an OperatorGroup, which provides Operator namespacing information to OLM; OLM creates two OperatorGroup's by default, one of which can be used for globally scoped Operators.

These resources can be created from bundle data with minimal user input. They can also be created from manifests defined by the user; however, the SDK cannot make guarantees that user-defined manifests will work as expected.

Use of operator-framework/api validation

Static validation is necessary for users to determine problems before deploying their Operator. As we all know, static bugs are usually more tractable than runtime bugs, especially those discovered in a live cluster. The operator-framework/api repo intends to house a validation library for static, and potentially runtime, validation. The SDK should use this library as the source of truth for the qualities of a valid OLM manifest. This repo is a work-in-progress, and should be used as soon as it is ready.

Risks and Mitigations

There are fewer risks with this approach than others because external libraries that define OLM components are used whenever possible, ensuring maximum compatibility.

One risk factor is how hidden OLM nuances are from users. Much of how an Operator is deployed using a registry and OLM resources like Subscription's is complex, and understanding each component is necessary for true self sufficiency. However good documentation can help direct users towards solutions. There is also an ongoing effort to reduce the complexity of OLM metadata requirements.

Design Details

Test Plan

Note: Section not required until targeted at a release.

Consider the following in developing a test plan for this enhancement:

  • Will there be e2e and integration tests, in addition to unit tests?
  • How will it be tested in isolation vs with other components?

No need to outline all of the test cases, just the general strategy. Anything that would count as tricky in the implementation and anything particularly challenging to test should be called out.

All code is expected to have adequate tests (eventually with coverage expectations).

Graduation Criteria

Note: Section not required until targeted at a release.

Define graduation milestones.

These may be defined in terms of API maturity, or as something else. Initial proposal should keep this high-level with a focus on what signals will be looked at to determine graduation.

Consider the following in developing the graduation criteria for this enhancement:

  • Maturity levels - Dev Preview, Tech Preview, GA
  • Deprecation

Clearly define what graduation means.

Examples

These are generalized examples to consider, in addition to the aforementioned maturity levels.

Dev Preview -> Tech Preview
  • Ability to utilize the enhancement end to end
  • End user documentation, relative API stability
  • Sufficient test coverage
  • Gather feedback from users rather than just developers
Tech Preview -> GA
  • More testing (upgrade, downgrade, scale)
  • Sufficient time for feedback
  • Available by default

For non-optional features moving to GA, the graduation criteria must include end to end tests.

Removing a deprecated feature
  • Announce deprecation and support policy of the existing feature
  • Deprecate the feature

Upgrade / Downgrade Strategy

If applicable, how will the component be upgraded and downgraded? Make sure this is in the test plan.

Consider the following in developing an upgrade/downgrade strategy for this enhancement:

  • What changes (in invocations, configurations, API use, etc.) is an existing cluster required to make on upgrade in order to keep previous behavior?
  • What changes (in invocations, configurations, API use, etc.) is an existing cluster required to make on upgrade in order to make use of the enhancement?

Version Skew Strategy

How will the component handle version skew with other components? What are the guarantees? Make sure this is in the test plan.

Consider the following in developing a version skew strategy for this enhancement:

  • During an upgrade, we will always have skew among components, how will this impact your work?
  • Does this enhancement involve coordinating behavior in the control plane and in the kubelet? How does an n-2 kubelet without this feature available behave when this feature is used?
  • Will any other components on the node change? For example, changes to CSI, CRI or CNI may require updating that component before the kubelet.

Implementation History

Major milestones in the life cycle of a proposal should be tracked in Implementation History.

Drawbacks

The idea is to find the best form of an argument why this enhancement should not be implemented.

Alternatives

Similar to the Drawbacks section the Alternatives section is used to highlight and record other possible approaches to delivering the value proposed by an enhancement.

Infrastructure Needed

Use this section if you need things from the project. Examples include a new subproject, repos requested, github details, and/or testing infrastructure.

Listing these here allows the community to get the process for these resources started right away.