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# Automatic Upgrades For Failed Operator Installations

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<!-- toc -->
- [Release Signoff Checklist](#release-signoff-checklist)
- [Summary](#summary)
- [Motivation](#motivation)
- [Goals](#goals)
- [Non-Goals](#non-goals)
- [Proposal](#proposal)
- [User Stories (Optional)](#user-stories-optional)
- [Story 1](#story-1)
- [Story 2](#story-2)
- [Notes/Constraints/Caveats (Optional)](#notesconstraintscaveats-optional)
- [Risks and Mitigations](#risks-and-mitigations)
- [Design Details](#design-details)
- [Test Plan](#test-plan)
- [Graduation Criteria](#graduation-criteria)
- [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
- [Version Skew Strategy](#version-skew-strategy)
- [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
- [Feature Enablement and Rollback](#feature-enablement-and-rollback)
- [Rollout, Upgrade and Rollback Planning](#rollout-upgrade-and-rollback-planning)
- [Monitoring Requirements](#monitoring-requirements)
- [Dependencies](#dependencies)
- [Scalability](#scalability)
- [Troubleshooting](#troubleshooting)
- [Implementation History](#implementation-history)
- [Drawbacks](#drawbacks)
- [Alternatives](#alternatives)
- [Infrastructure Needed (Optional)](#infrastructure-needed-optional)
<!-- /toc -->

## Release Signoff Checklist

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- [ ] (R) KEP approvers have approved the KEP status as `implementable`
- [ ] (R) Design details are appropriately documented
- [ ] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input (including test refactors)
- [ ] e2e Tests for all Beta API Operations (endpoints)
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- [ ] (R) Minimum Two Week Window for GA e2e tests to prove flake free
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[kubernetes.io]: https://kubernetes.io/
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[kubernetes/website]: https://git.k8s.io/website

## Summary

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This proposal describes modifications to the Operator Lifecycle Manager (OLM) that enable users to opt-into "fail forward" operator upgrades; that is, automatically upgrading an operator even when its deployment has failed.

## Motivation

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Today, when an operator's installation fails due to a defect, users must manually reconcile k8s resources -- e.g delete the operator -- before it can be upgraded to a working version. Two of the most common defects are:

1. An issue with an operator's manifests -- e.g. a typo -- prevents resources from being applied to a cluster
2. An operator crashes due to a bug

In both of these scenarios, OLM refuses to apply further upgrades even when there's potential to automatically resolve the issue.

### Goals

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- Provide a mechanism to enable upgrades from failed operator installations without manual intervention
- Once automatic upgrades of a failed operator are enabled, no further intervention by the user is necessary to ensure available upgrades are applied

### Non-Goals

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-->
- Automatically upgrade from failed installations without user opt-in
- Provide typical upgrade safety; e.g. no data loss, CustomResourceDefinition (CRD) API schema compatibility, etc

## Proposal

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Introduce a field on the `Subscription` API that lets users opt-into "fail forward". When enabled and an upgrade is available for a package, OLM will **always** resolve the upgrade and perform a potentially disruptive/destructive installation of the new version.

**Alternative:** Put a flag on OLMConfig resource instead of on a Subscription. This flag can make "fail forward" behavior global -- i.e. for all operator installations -- or, can accept a list of Subscriptions or Namespaces to do this for.

**Edge Cases:**

- Target version has an incompatible CRD schema
- More than one package (operator) installed to a namespace
- Existing version contains APIServices/Webhooks

**Open Questions:**

- Do transient errors constitute "install failure"; e.g. when network issues that blocked an installation are resolved, will installation eventually succeed?

TODO find home:

- Questions:
- What's the UX around failed rollouts?
- What's required in order to enable more control over failed rollouts, e.g. more advanced health checks/probes/etc.
- Can you configure the failed rollouts behavior, or is this a one-off for SD going forward? Does this design need to account for future asks around supporting extended deployment stategies (canary, b/g, etc.)
- https://issues.redhat.com/browse/OLM-2311
- Do we need to support purging resources and/or provide trivial self healing mechanisms?
- If so: What happens when a vital namespaced-scoped resource is deleted during a failed rollout (e.g. ServiceAccount) and the result is a degraded operator installation?
- What kind of granularity do we need to expose?
- What's the downstream requirements for introducing new APIs that are opt-in?

**Implementation paths:**

There are two independent paths to implement this feature:

1. Extend the existing `InstallPlan` controllers
2. Introduce APIs and behaviors from `rukpak`

Details (rukpak):

- Introduce a new InstallPlan-esq API that manages Bundle/BundleInstance resources
- Replace InstallPlans with Bundles/BundleInstances
- Provisioner looks at Subscriptions and OperatorGroups
- creates cluster-scoped Bundles/BundleInstances with manifests scoped to the OperatorGroup
- Provisioner is responsible for making pivoting decisions
- Extending the existing InstallPlan-related code to support the new APIs wouldn't be trivial, and the existing catalog-operator codebase is already due for a refactoring


Details (extend existing):

- Extend the current InstallPlan API when the opt-in mechanism has been enabled, and only the new APIs are created in the list of steps; implemented a provisioner responsible for this use-case
- Support enabling a mechanism for exposing scope to the BundleInstance API, e.g. an annotation that contains the desired operator installation namespace
- What are the existing OLM features that would need to be present in an implementation that's centered around the new APIs
- Safely rolling out CRD changes

### User Stories (Optional)

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#### Story 1

#### Story 2

### Notes/Constraints/Caveats (Optional)

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#### Happy Path Install

The "Happy Path Install" refers to the scenario where an operator is installed without any issues occuring.

Consider a namespace, `my-ns`, containing the following resources:

1. A `CatalogSource`, `my-cs`
- points to a valid catalog image
- contains a linear bundle upgrade graph for package `pkg-a`; i.e. `bundle-vN` replaces `bundle-v(N-1)` replaces `bundle-v(N-2)` replaces `...`
- all bundles in `pkg-a` support the same install modes
- all bundles in `pkg-a` provide the same CRD `foos.my.com`
2. An `OperatorGroup`, `my-og`
- configured to any one of the install modes supported by bundles in `pkg-a`

Assuming a clean cluster -- i.e. no other namespaces, CRDs, APIServices, what-have-you -- with OLM, the latest bundle in `pkg-a`, `bundle-vN`, can be installed by creating `Subscription` `my-sub`:

- in `my-ns`
- with a spec requesting `pkg-a` from `my-cs`

When `my-sub` is created, OLM will perform the following sequence (roughly):

1. Gather all `Subscriptions` and `CSVs` in `my-ns`
- in this case, only `Subscription` `my-sub` is found
2. Gather all available bundles in `my-cs`
3. Massage the output of 1. and 2. into a filtered set of candidate bundles to install
4. Feed the output of 3. to a SAT-Solver, which determines _the_ set of bundles that satisfies all given constraints (if such a set exists)
- here, it resolves the latest bundle `bundle-vN`
5. Create an InstallPlan in `my-ns`, containing instructions to apply new `Subscriptions` for and manifests from yet-to-be-installed bundles resolved in 4.
- in this case the `Subscription` for `bundle-vN` in `pkg-a` already exists (`my-sub`), so only instructions to install manifests for `bundle-vN` are added
- this step also generates and adds RBAC resources to the `InstallPlan` based on the permissions fields of the CSVs in each bundle
6. Execute the InstallPlan created in 5.
- all `Subscriptions` and namespace-scoped bundle manifests are automatically namespaced to `my-ns`
- bundle resources are applied sequentially by a partial-order prioritizing CRDs, then CSVs, then all other kinds (TODO: verify this)
- this means CRD `foos.my.com` is created _before_ CSV `csv-vN`

While this is happening, a separate controller in OLM is concurrently performing an independent sequence:

1. Gather CSVs and `OperatorGroups` in `my-ns`
- only `csv-vN` and `my-og` is found
2. Determine if any API ownership conflicts exist between CSVs in `my-ns`
- an "API ownership conflict" exists when more than one unrelated CSV provides the same CRD, APIService, and/or Webhook
- CSVs are related if there exists a linear upgrade path between them; i.e. have a direct or transitive "replaces" fields
- for this `csv-vN` in this case, no conflict exists
3. Determine if any API ownership conflicts exist between CSVs in intersecting `OperatorGroups`
- `OperatorGroups` intersect when they set of APIs they select overlap
- here, there are no other `OperatorGroups` on the cluster, so there's no conflict
4. Generate and apply `Deployments` from CSVs in `my-ns`
5.

### Risks and Mitigations

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#### Data Loss

## Design Details

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### Test Plan

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### Graduation Criteria

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[conformance tests]: https://git.k8s.io/community/contributors/devel/sig-architecture/conformance-tests.md

#### Deprecation

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### Upgrade / Downgrade Strategy

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### Version Skew Strategy

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## Production Readiness Review Questionnaire

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### Feature Enablement and Rollback

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###### How can this feature be enabled / disabled in a live cluster?

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###### What happens if we reenable the feature if it was previously rolled back?

###### Are there any tests for feature enablement/disablement?

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### Rollout, Upgrade and Rollback Planning

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###### How can a rollout or rollback fail? Can it impact already running workloads?

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###### What specific metrics should inform a rollback?

<!--
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###### Were upgrade and rollback tested? Was the upgrade->downgrade->upgrade path tested?

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###### Is the rollout accompanied by any deprecations and/or removals of features, APIs, fields of API types, flags, etc.?

<!--
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### Monitoring Requirements

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###### How can an operator determine if the feature is in use by workloads?

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###### How can someone using this feature know that it is working for their instance?

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- [ ] Events
- Event Reason:
- [ ] API .status
- Condition name:
- Other field:
- [ ] Other (treat as last resort)
- Details:

###### What are the reasonable SLOs (Service Level Objectives) for the enhancement?

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These goals will help you determine what you need to measure (SLIs) in the next
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###### What are the SLIs (Service Level Indicators) an operator can use to determine the health of the service?

<!--
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-->

- [ ] Metrics
- Metric name:
- [Optional] Aggregation method:
- Components exposing the metric:
- [ ] Other (treat as last resort)
- Details:

###### Are there any missing metrics that would be useful to have to improve observability of this feature?

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### Dependencies

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###### Does this feature depend on any specific services running in the cluster?

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and creating new ones, as well as about cluster-level services (e.g. DNS):
- [Dependency name]
- Usage description:
- Impact of its outage on the feature:
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### Scalability

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###### Will enabling / using this feature result in any new API calls?

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###### Will enabling / using this feature result in introducing new API types?

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- Supported number of objects per cluster
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###### Will enabling / using this feature result in any new calls to the cloud provider?

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###### Will enabling / using this feature result in increasing size or count of the existing API objects?

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- Estimated increase in size: (e.g., new annotation of size 32B)
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###### Will enabling / using this feature result in increasing time taken by any operations covered by existing SLIs/SLOs?

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Think about adding additional work or introducing new steps in between
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###### Will enabling / using this feature result in non-negligible increase of resource usage (CPU, RAM, disk, IO, ...) in any components?

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Things to keep in mind include: additional in-memory state, additional
non-trivial computations, excessive access to disks (including increased log
volume), significant amount of data sent and/or received over network, etc.
This through this both in small and large cases, again with respect to the
[supported limits].

[supported limits]: https://git.k8s.io/community//sig-scalability/configs-and-limits/thresholds.md
-->

### Troubleshooting

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This section must be completed when targeting beta to a release.

The Troubleshooting section currently serves the `Playbook` role. We may consider
splitting it into a dedicated `Playbook` document (potentially with some monitoring
details). For now, we leave it here.
-->

###### How does this feature react if the API server and/or etcd is unavailable?

###### What are other known failure modes?

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For each of them, fill in the following information by copying the below template:
- [Failure mode brief description]
- Detection: How can it be detected via metrics? Stated another way:
how can an operator troubleshoot without logging into a master or worker node?
- Mitigations: What can be done to stop the bleeding, especially for already
running user workloads?
- Diagnostics: What are the useful log messages and their required logging
levels that could help debug the issue?
Not required until feature graduated to beta.
- Testing: Are there any tests for failure mode? If not, describe why.
-->

###### What steps should be taken if SLOs are not being met to determine the problem?

## Implementation History

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Major milestones in the lifecycle of a KEP should be tracked in this section.
Major milestones might include:
- the `Summary` and `Motivation` sections being merged, signaling SIG acceptance
- the `Proposal` section being merged, signaling agreement on a proposed design
- the date implementation started
- the first Kubernetes release where an initial version of the KEP was available
- the version of Kubernetes where the KEP graduated to general availability
- when the KEP was retired or superseded
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## Drawbacks

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Why should this KEP _not_ be implemented?
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## Alternatives

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What other approaches did you consider, and why did you rule them out? These do
not need to be as detailed as the proposal, but should include enough
information to express the idea and why it was not acceptable.
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## Infrastructure Needed (Optional)

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Use this section if you need things from the project/SIG. Examples include a
new subproject, repos requested, or GitHub details. Listing these here allows a
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