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| 1 | +# KEP-2365: IngressClass Namespaced Params |
| 2 | + |
| 3 | +<!-- toc --> |
| 4 | +- [Release Signoff Checklist](#release-signoff-checklist) |
| 5 | +- [Summary](#summary) |
| 6 | +- [Motivation](#motivation) |
| 7 | + - [Goals](#goals) |
| 8 | + - [Non-Goals](#non-goals) |
| 9 | +- [Proposal](#proposal) |
| 10 | + - [Risks and Mitigations](#risks-and-mitigations) |
| 11 | +- [Design Details](#design-details) |
| 12 | + - [Test Plan](#test-plan) |
| 13 | + - [Unit Tests](#unit-tests) |
| 14 | + - [Graduation Criteria](#graduation-criteria) |
| 15 | + - [Alpha release](#alpha-release) |
| 16 | + - [Alpha -> Beta Graduation](#alpha---beta-graduation) |
| 17 | + - [Beta -> GA Graduation](#beta---ga-graduation) |
| 18 | + - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy) |
| 19 | + - [Version Skew Strategy](#version-skew-strategy) |
| 20 | +- [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire) |
| 21 | + - [Feature Enablement and Rollback](#feature-enablement-and-rollback) |
| 22 | + - [Rollout, Upgrade and Rollback Planning](#rollout-upgrade-and-rollback-planning) |
| 23 | + - [Monitoring Requirements](#monitoring-requirements) |
| 24 | + - [Dependencies](#dependencies) |
| 25 | + - [Scalability](#scalability) |
| 26 | + - [Troubleshooting](#troubleshooting) |
| 27 | +- [Implementation History](#implementation-history) |
| 28 | +- [Drawbacks](#drawbacks) |
| 29 | +- [Alternatives](#alternatives) |
| 30 | +<!-- /toc --> |
| 31 | + |
| 32 | +## Release Signoff Checklist |
| 33 | + |
| 34 | +Items marked with (R) are required *prior to targeting to a milestone / release*. |
| 35 | + |
| 36 | +- [ ] (R) Enhancement issue in release milestone, which links to KEP dir in [kubernetes/enhancements] (not the initial KEP PR) |
| 37 | +- [x] (R) KEP approvers have approved the KEP status as `implementable` |
| 38 | +- [x] (R) Design details are appropriately documented |
| 39 | +- [x] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input |
| 40 | +- [x] (R) Graduation criteria is in place |
| 41 | +- [x] (R) Production readiness review completed |
| 42 | +- [x] (R) Production readiness review approved |
| 43 | +- [ ] "Implementation History" section is up-to-date for milestone |
| 44 | +- [ ] User-facing documentation has been created in [kubernetes/website], for publication to [kubernetes.io] |
| 45 | +- [ ] Supporting documentation—e.g., additional design documents, links to mailing list discussions/SIG meetings, relevant PRs/issues, release notes |
| 46 | + |
| 47 | +## Summary |
| 48 | + |
| 49 | +This KEP proposes adding new Scope and Namespace fields to the IngressClass |
| 50 | +ParametersRef field. |
| 51 | + |
| 52 | +## Motivation |
| 53 | + |
| 54 | +After the initial release of IngressClass, a number of use cases called for the |
| 55 | +ability to reference namespace-scoped Parameters. For example, one could use a |
| 56 | +GatewayClass parameters CR to describe how and where a controller should be |
| 57 | +provisioned. This same thought process was also happening in the Service APIs |
| 58 | +subproject. It was ultimately deemed worthwhile for GatewayClass if we could |
| 59 | +also gain approval for a parallel API change to IngressClass. |
| 60 | + |
| 61 | +### Goals |
| 62 | + |
| 63 | +- Allow referencing namespace-scoped Parameters resources. |
| 64 | + |
| 65 | +### Non-Goals |
| 66 | + |
| 67 | +- Requiring all Parameters resources to be namespace-scoped. |
| 68 | + |
| 69 | +## Proposal |
| 70 | + |
| 71 | +Add new Scope and Namespace fields to the IngressClass ParametersRef field. |
| 72 | + |
| 73 | +### Risks and Mitigations |
| 74 | + |
| 75 | +The option to reference namespace-scoped Parameters resources could lead to |
| 76 | +confusion. It is relatively rare for resource references to be able to target |
| 77 | +both cluster-scoped and namespace-scoped resources. We believe that the |
| 78 | +advantages of this KEP outweigh this potential confusion. |
| 79 | + |
| 80 | +## Design Details |
| 81 | + |
| 82 | +This will result in adding a new `IngressClassParametersReference` type that |
| 83 | +closely mirrors the existing `TypedLocalObjectReference` type that is currently |
| 84 | +in use. |
| 85 | + |
| 86 | +```golang |
| 87 | +// IngressClassParametersReference identifies an API object. This can be used |
| 88 | +// to specify a cluster-scoped or namespace-scoped resource. |
| 89 | +type IngressClassParametersReference struct { |
| 90 | + // APIGroup is the group for the resource being referenced. If APIGroup is not |
| 91 | + // specified, the specified Kind must be in the core API group. For any other |
| 92 | + // third-party types, APIGroup is required. |
| 93 | + // +optional |
| 94 | + APIGroup *string |
| 95 | + // Kind is the type of resource being referenced. |
| 96 | + Kind string |
| 97 | + // Name is the name of resource being referenced. |
| 98 | + Name string |
| 99 | + // Scope represents if this refers to a cluster or namespace scoped resource. |
| 100 | + // This may be set to "cluster" or "namespace". |
| 101 | + // Default: "cluster" |
| 102 | + Scope string |
| 103 | + // Namespace is the namespace of the resource being referenced. This field is |
| 104 | + // required when scope is set to "namespace". |
| 105 | + // +optional |
| 106 | + Namespace *string |
| 107 | +} |
| 108 | +``` |
| 109 | + |
| 110 | +Use of these new `Scope` and `Namespace` fields will be guarded by a new |
| 111 | +`IngressClassNamespacedParams` feature gate. |
| 112 | + |
| 113 | +### Test Plan |
| 114 | + |
| 115 | +#### Unit Tests |
| 116 | +- When feature gate is disabled: |
| 117 | + - Ensure that namespace and scope fields can not be set on a newly created |
| 118 | + IngressClass resource. |
| 119 | + - Ensure that namespace and scope field can not be changed if it is not |
| 120 | + already set on an IngressClass resource. |
| 121 | + - Ensure that namespace and scope field can be changed if it is already set on |
| 122 | + an IngressClass resource. |
| 123 | +- When feature gate is enabled: |
| 124 | + - Ensure that namespace and scope field can be set on a newly created |
| 125 | + IngressClass resource. |
| 126 | + - Ensure that namespace and scope field can be changed if it is not already |
| 127 | + set on an IngressClass resource. |
| 128 | + - Ensure that namespace and scope field can be changed if it is already set on |
| 129 | + an IngressClass resource. |
| 130 | + |
| 131 | +### Graduation Criteria |
| 132 | + |
| 133 | +#### Alpha release |
| 134 | + |
| 135 | +- Implementation complete |
| 136 | +- Test plan complete |
| 137 | +- Documentation added covering how params resources should and should not be |
| 138 | + used |
| 139 | + |
| 140 | +#### Alpha -> Beta Graduation |
| 141 | + |
| 142 | +- Existed in alpha for at least 1 minor release |
| 143 | + |
| 144 | +#### Beta -> GA Graduation |
| 145 | + |
| 146 | +- Existed in beta for at least 1 minor release |
| 147 | + |
| 148 | +### Upgrade / Downgrade Strategy |
| 149 | + |
| 150 | +N/A |
| 151 | + |
| 152 | +### Version Skew Strategy |
| 153 | + |
| 154 | +See unit tests above. |
| 155 | + |
| 156 | +## Production Readiness Review Questionnaire |
| 157 | + |
| 158 | +### Feature Enablement and Rollback |
| 159 | + |
| 160 | +* **How can this feature be enabled / disabled in a live cluster?** |
| 161 | + - [x] Feature gate (also fill in values in `kep.yaml`) |
| 162 | + - Feature gate name: IngressClassNamespacedParams |
| 163 | + - Components depending on the feature gate: API Server |
| 164 | + |
| 165 | +* **Does enabling the feature change any default behavior?** |
| 166 | + A new API field can be set. This may enable new behavior for Ingress |
| 167 | + controllers that support the field. |
| 168 | + |
| 169 | +* **Can the feature be disabled once it has been enabled (i.e. can we roll back |
| 170 | + the enablement)?** |
| 171 | + Yes. |
| 172 | + |
| 173 | +* **What happens if we reenable the feature if it was previously rolled back?** |
| 174 | + The fields becomes accessible again. |
| 175 | + |
| 176 | +* **Are there any tests for feature enablement/disablement?** |
| 177 | + Yes. |
| 178 | + |
| 179 | +### Rollout, Upgrade and Rollback Planning |
| 180 | + |
| 181 | +* **How can a rollout fail? Can it impact already running workloads?** |
| 182 | + N/A |
| 183 | + |
| 184 | +* **What specific metrics should inform a rollback?** |
| 185 | + N/A |
| 186 | + |
| 187 | +* **Were upgrade and rollback tested? Was the upgrade->downgrade->upgrade path tested?** |
| 188 | + N/A |
| 189 | + |
| 190 | +* **Is the rollout accompanied by any deprecations and/or removals of features, |
| 191 | + APIs, fields of API types, flags, etc.?** |
| 192 | + No. |
| 193 | + |
| 194 | +### Monitoring Requirements |
| 195 | + |
| 196 | +* **How can an operator determine if the feature is in use by workloads?** |
| 197 | + N/A |
| 198 | + |
| 199 | +* **What are the SLIs (Service Level Indicators) an operator can use to |
| 200 | + determine the health of the service?** |
| 201 | + N/A |
| 202 | + |
| 203 | +* **What are the reasonable SLOs (Service Level Objectives) for the above SLIs?** |
| 204 | + N/A |
| 205 | + |
| 206 | +* **Are there any missing metrics that would be useful to have to improve |
| 207 | + observability of this feature?** |
| 208 | + No. |
| 209 | + |
| 210 | +### Dependencies |
| 211 | + |
| 212 | +* **Does this feature depend on any specific services running in the cluster?** |
| 213 | + No |
| 214 | + |
| 215 | +### Scalability |
| 216 | + |
| 217 | +* **Will enabling / using this feature result in any new API calls?** |
| 218 | + No |
| 219 | + |
| 220 | +* **Will enabling / using this feature result in introducing new API types?** |
| 221 | + Yes, IngressClassParametersReference. |
| 222 | + |
| 223 | +* **Will enabling / using this feature result in any new calls to the cloud |
| 224 | + provider?** |
| 225 | + No |
| 226 | + |
| 227 | +* **Will enabling / using this feature result in increasing size or count of the |
| 228 | + existing API objects?** |
| 229 | + Will very slightly increase the size of the IngressClass resource. Generally |
| 230 | + less than 10 of these resources should exist in a cluster. |
| 231 | + |
| 232 | +* **Will enabling / using this feature result in increasing time taken by any |
| 233 | + operations covered by [existing SLIs/SLOs]?** |
| 234 | + No |
| 235 | + |
| 236 | +* **Will enabling / using this feature result in non-negligible increase of |
| 237 | + resource usage (CPU, RAM, disk, IO, ...) in any components?** |
| 238 | + No |
| 239 | + |
| 240 | +### Troubleshooting |
| 241 | + |
| 242 | +* **How does this feature react if the API server and/or etcd is unavailable?** |
| 243 | + N/A |
| 244 | + |
| 245 | +* **What are other known failure modes?** |
| 246 | + N/A |
| 247 | + |
| 248 | +* **What steps should be taken if SLOs are not being met to determine the problem?** |
| 249 | + N/A |
| 250 | + |
| 251 | +## Implementation History |
| 252 | + |
| 253 | +- January 28, 2021: KEP written |
| 254 | + |
| 255 | +## Drawbacks |
| 256 | + |
| 257 | +Potential for confusion with a params reference that can point to both namespace |
| 258 | +scoped and cluster scoped resources. |
| 259 | + |
| 260 | +## Alternatives |
| 261 | + |
| 262 | +- Each controller could assume all parameters were in a predefined namespace. |
| 263 | + This would likely lead to more confusion since it would be different for each |
| 264 | + implementation. |
| 265 | + |
| 266 | +- We could not support namespace-scoped parameters references. This would be |
| 267 | + simplest but would rule out some compelling use cases. |
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