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Add TLS adherance feature gate #2680

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88 changes: 88 additions & 0 deletions config/v1/tests/apiservers.config.openshift.io/TLSAdherence.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,88 @@
apiVersion: apiextensions.k8s.io/v1
name: "APIServer"
crdName: apiservers.config.openshift.io
featureGates:
- TLSAdherence
tests:
onCreate:
- name: Should be able to create with tlsAdherence set to LegacyExternalAPIServerComponentsOnly
initial: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: LegacyExternalAPIServerComponentsOnly
expected: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
audit:
profile: Default
tlsAdherence: LegacyExternalAPIServerComponentsOnly
- name: Should be able to create with tlsAdherence set to StrictAllComponents
initial: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: StrictAllComponents
expected: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
audit:
profile: Default
tlsAdherence: StrictAllComponents
- name: Should reject invalid tlsAdherence value
initial: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: InvalidValue
expectedError: 'spec.tlsAdherence: Unsupported value: "InvalidValue": supported values: "LegacyExternalAPIServerComponentsOnly", "StrictAllComponents"'
onUpdate:
- name: Should be able to update tlsAdherence from LegacyExternalAPIServerComponentsOnly to StrictAllComponents
initial: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: LegacyExternalAPIServerComponentsOnly
updated: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: StrictAllComponents
expected: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
audit:
profile: Default
tlsAdherence: StrictAllComponents
- name: Should be able to update tlsAdherence from StrictAllComponents to LegacyExternalAPIServerComponentsOnly
initial: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: StrictAllComponents
updated: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: LegacyExternalAPIServerComponentsOnly
expected: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
audit:
profile: Default
tlsAdherence: LegacyExternalAPIServerComponentsOnly
- name: Should not allow removing tlsAdherence once set
initial: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec:
tlsAdherence: StrictAllComponents
updated: |
apiVersion: config.openshift.io/v1
kind: APIServer
spec: {}
expectedError: "tlsAdherence may not be removed once set"
58 changes: 58 additions & 0 deletions config/v1/types_apiserver.go
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ type APIServer struct {
Status APIServerStatus `json:"status"`
}

// +openshift:validation:FeatureGateAwareXValidation:featureGate=TLSAdherence,rule="has(oldSelf.tlsAdherence) ? has(self.tlsAdherence) : true",message="tlsAdherence may not be removed once set"
type APIServerSpec struct {
// servingCert is the TLS cert info for serving secure traffic. If not specified, operator managed certificates
// will be used for serving secure traffic.
Expand Down Expand Up @@ -62,6 +63,37 @@ type APIServerSpec struct {
// The current default is the Intermediate profile.
// +optional
TLSSecurityProfile *TLSSecurityProfile `json:"tlsSecurityProfile,omitempty"`
// tlsAdherence controls which components in the cluster adhere to the TLS security profile
// configured on this APIServer resource.
//
// Valid values are "LegacyExternalAPIServerComponentsOnly" and "StrictAllComponents".
//
// When set to "LegacyExternalAPIServerComponentsOnly", only the externally exposed
// API server components (kube-apiserver, openshift-apiserver, oauth-apiserver) honor the configured
// TLS profile. Other components continue to use their individual TLS configurations.
//
// When set to "StrictAllComponents", all components must honor the configured TLS profile
// unless they have a component-specific TLS configuration that overrides it.
// This mode is recommended for security-conscious deployments and is required for
// certain compliance frameworks.
//
// Note: Some components such as Kubelet and IngressController have their own dedicated TLS
// configuration mechanisms via KubeletConfig and IngressController CRs respectively. When these
// component-specific TLS configurations are set, they take precedence over the cluster-wide
// tlsSecurityProfile. When not set, these components fall back to the cluster-wide default.
//
// Components that encounter an unknown value for tlsAdherence should treat it as "StrictAllComponents"
// and log a warning to ensure forward compatibility while defaulting to the more secure behavior.
//
// This field is optional.
// When omitted, this means the user has no opinion and the platform is left to choose reasonable defaults.
// These defaults are subject to change over time.
// The current default is LegacyExternalAPIServerComponentsOnly.
//
// Once set, this field may be changed to a different value, but may not be removed.
// +openshift:enable:FeatureGate=TLSAdherence
// +optional
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@joelanford joelanford Feb 3, 2026

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We need to configure validation on this field, and set the default.

// +kubebuilder:validation:items:Enum:=LegacyExternalAPIServerComponentsOnly;StrictAllComponents
// +kubebuilder:default:=LegacyExternalAPIServerComponentsOnly

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@joelanford joelanford Feb 3, 2026

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Oh I see you are defining the Enum validation on the type, which is fine. Let's also include the +kubebuilder:default marker there as well.

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@joelanford joelanford Feb 3, 2026

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Hmm, reading the tlsAdherence description again, it seems like you are wanting it to be possible for an empty string to be allowed to be persisted for this field in etcd, which would allow us in theory to change the default semantic later in the future from legacy to strict without a change in the actual tlsAdherence value.

In practice, I think the problem with that idea is that each component essentially has their own implementation of this API and we'd have to do a really good job coordinating a semantic switch from legacy to strict.

What do folks think about:

  1. Actually writing LegacyExternalAPIServerComponentsOnly to etcd by default.
  2. Telling implementers they specifically only need to look for StrictAllComponents and will not have to worry about the possibility of "" with changing semantics later.
  3. When want to set StrictAllComponents as the new default, we make sure newly installed clusters get that, and we potentially block upgrades of clusters that still use LegacyExternalAPIServerComponentsOnly? Or maybe there's some other way to encourage users to switch to StrictAllComponents?

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@everettraven everettraven Feb 3, 2026

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For configuration APIs we generally try to avoid setting the default via +kubebuilder:default marker so that we can change the default behavior of the "no-opinion" mechanism.

In this case, I don't think we will be doing that but I still wouldn't use the +kubebuilder:default marker because then we won't be able to distinguish whether or not the user intentionally set the field or if we defaulted it on their behalf and you technically get locked into that default being a contractual default.

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@joelanford joelanford Feb 4, 2026

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so that we can change the default behavior of the "no-opinion" mechanism.

Thanks, I was hoping you'd have some good advice here. It is the intent to eventually make all components honor the cluster-wide default, so I supposed we'll just have to deal with trying to coordinate a semantic change across a bunch of components at once when the time comes.

To facilitate that, I'd suggest a library-go function somehow like this:

// in configv1
const TLSAdherenceNoOpinion = ""
func ShouldAllComponentsAdhere(tlsAdherence configv1.TLSAdherence) bool {
    if tlsAdherence == configv1.TLSAdherenceNoOpinion || tlsAdherence == configv1.LegacyExternalAPIServerComponentsOnly {
        return false
    }
    return true
}

And then when we want to change the semantic, we'd update that function to:

func ShouldAllComponentsAdhere(tlsAdherence configv1.TLSAdherence) bool {
    if tlsAdherence == configv1.LegacyExternalAPIServerComponentsOnly {
        return false
    }
    return true
}

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@everettraven everettraven Feb 4, 2026

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That aligns with what I envisioned.

Can we make sure to update the EP with a mention of this kind of check/library that implementors are expected to use?

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@richardsonnick richardsonnick Feb 4, 2026

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Added a mention of this helper function.
Also created a draft diff in library-go to add this function: openshift/library-go#2114

Will need to land this first to get the TLSAdherencePolicy type into library-go

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The behavior for unknown values seem inconsistent with the behavior for unset/empty values. Shouldn't unknown values lead to a warning and setting the default value instead of StrictAllComponents ? This would be less surprising for both users and implementers ?

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I'm not super opinionated on what the "unknown" case means for components, but I think StrictAllComponents is reasonable.

I suspect that we probably won't add many new allowed values here. Assuming that we do have a scenario where we've added a new value that might be unknown for some components, I think the current assumption of unknown != explicit legacy choice (that all components should be aware of) being that components should respect the configuration defined here is reasonable.

Issuing some kind of warning sounds reasonable to me. You wouldn't want to modify this value based on one component not understanding the value here because other components may understand the value.

TLSAdherence TLSAdherencePolicy `json:"tlsAdherence,omitempty"`
// audit specifies the settings for audit configuration to be applied to all OpenShift-provided
// API servers in the cluster.
// +optional
Expand Down Expand Up @@ -237,6 +269,32 @@ const (
type APIServerStatus struct {
}

// TLSAdherencePolicy defines which components adhere to the TLS security profile.
// Implementors should use the ShouldAllComponentsAdhere helper function from library-go
// rather than checking these values directly.
// +kubebuilder:validation:Enum=LegacyExternalAPIServerComponentsOnly;StrictAllComponents
type TLSAdherencePolicy string

const (
// TLSAdherencePolicyNoOpinion represents an empty/unset value for tlsAdherence.
// This value cannot be explicitly set and is only present when the field is omitted.
// When the field is omitted, the cluster defaults to LegacyExternalAPIServerComponentsOnly
// behavior. Components should treat this the same as LegacyExternalAPIServerComponentsOnly.
TLSAdherencePolicyNoOpinion TLSAdherencePolicy = ""

// TLSAdherencePolicyLegacyExternalAPIServerComponentsOnly means only the externally exposed
// API server components (kube-apiserver, openshift-apiserver, oauth-apiserver) honor
// the configured TLS profile. Other components continue to use their individual TLS
// configurations.
TLSAdherencePolicyLegacyExternalAPIServerComponentsOnly TLSAdherencePolicy = "LegacyExternalAPIServerComponentsOnly"

// TLSAdherencePolicyStrictAllComponents means all components must honor the configured TLS
// profile unless they have a component-specific TLS configuration that overrides it.
// This mode is recommended for security-conscious deployments and is required
// for certain compliance frameworks.
TLSAdherencePolicyStrictAllComponents TLSAdherencePolicy = "StrictAllComponents"
)

// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// Compatibility level 1: Stable within a major release for a minimum of 12 months or 3 minor releases (whichever is longer).
Expand Down
37 changes: 37 additions & 0 deletions ...zz_generated.crd-manifests/0000_10_config-operator_01_apiservers-CustomNoUpgrade.crd.yaml
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Expand Up @@ -292,6 +292,40 @@ spec:
type: array
x-kubernetes-list-type: atomic
type: object
tlsAdherence:
description: |-
tlsAdherence controls which components in the cluster adhere to the TLS security profile
configured on this APIServer resource.
Valid values are "LegacyExternalAPIServerComponentsOnly" and "StrictAllComponents".
When set to "LegacyExternalAPIServerComponentsOnly", only the externally exposed
API server components (kube-apiserver, openshift-apiserver, oauth-apiserver) honor the configured
TLS profile. Other components continue to use their individual TLS configurations.
When set to "StrictAllComponents", all components must honor the configured TLS profile
unless they have a component-specific TLS configuration that overrides it.
This mode is recommended for security-conscious deployments and is required for
certain compliance frameworks.
Note: Some components such as Kubelet and IngressController have their own dedicated TLS
configuration mechanisms via KubeletConfig and IngressController CRs respectively. When these
component-specific TLS configurations are set, they take precedence over the cluster-wide
tlsSecurityProfile. When not set, these components fall back to the cluster-wide default.
Components that encounter an unknown value for tlsAdherence should treat it as "StrictAllComponents"
and log a warning to ensure forward compatibility while defaulting to the more secure behavior.
This field is optional.
When omitted, this means the user has no opinion and the platform is left to choose reasonable defaults.
These defaults are subject to change over time.
The current default is LegacyExternalAPIServerComponentsOnly.
Once set, this field may be changed to a different value, but may not be removed.
enum:
- LegacyExternalAPIServerComponentsOnly
- StrictAllComponents
type: string
tlsSecurityProfile:
description: |-
tlsSecurityProfile specifies settings for TLS connections for externally exposed servers.
Expand Down Expand Up @@ -427,6 +461,9 @@ spec:
type: string
type: object
type: object
x-kubernetes-validations:
- message: tlsAdherence may not be removed once set
rule: 'has(oldSelf.tlsAdherence) ? has(self.tlsAdherence) : true'
status:
description: status holds observed values from the cluster. They may not
be overridden.
Expand Down
37 changes: 37 additions & 0 deletions ...enerated.crd-manifests/0000_10_config-operator_01_apiservers-DevPreviewNoUpgrade.crd.yaml
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Expand Up @@ -292,6 +292,40 @@ spec:
type: array
x-kubernetes-list-type: atomic
type: object
tlsAdherence:
description: |-
tlsAdherence controls which components in the cluster adhere to the TLS security profile
configured on this APIServer resource.
Valid values are "LegacyExternalAPIServerComponentsOnly" and "StrictAllComponents".
When set to "LegacyExternalAPIServerComponentsOnly", only the externally exposed
API server components (kube-apiserver, openshift-apiserver, oauth-apiserver) honor the configured
TLS profile. Other components continue to use their individual TLS configurations.
When set to "StrictAllComponents", all components must honor the configured TLS profile
unless they have a component-specific TLS configuration that overrides it.
This mode is recommended for security-conscious deployments and is required for
certain compliance frameworks.
Note: Some components such as Kubelet and IngressController have their own dedicated TLS
configuration mechanisms via KubeletConfig and IngressController CRs respectively. When these
component-specific TLS configurations are set, they take precedence over the cluster-wide
tlsSecurityProfile. When not set, these components fall back to the cluster-wide default.
Components that encounter an unknown value for tlsAdherence should treat it as "StrictAllComponents"
and log a warning to ensure forward compatibility while defaulting to the more secure behavior.
This field is optional.
When omitted, this means the user has no opinion and the platform is left to choose reasonable defaults.
These defaults are subject to change over time.
The current default is LegacyExternalAPIServerComponentsOnly.
Once set, this field may be changed to a different value, but may not be removed.
enum:
- LegacyExternalAPIServerComponentsOnly
- StrictAllComponents
type: string
tlsSecurityProfile:
description: |-
tlsSecurityProfile specifies settings for TLS connections for externally exposed servers.
Expand Down Expand Up @@ -427,6 +461,9 @@ spec:
type: string
type: object
type: object
x-kubernetes-validations:
- message: tlsAdherence may not be removed once set
rule: 'has(oldSelf.tlsAdherence) ? has(self.tlsAdherence) : true'
status:
description: status holds observed values from the cluster. They may not
be overridden.
Expand Down
37 changes: 37 additions & 0 deletions ...nerated.crd-manifests/0000_10_config-operator_01_apiservers-TechPreviewNoUpgrade.crd.yaml
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Expand Up @@ -224,6 +224,40 @@ spec:
type: array
x-kubernetes-list-type: atomic
type: object
tlsAdherence:
description: |-
tlsAdherence controls which components in the cluster adhere to the TLS security profile
configured on this APIServer resource.

Valid values are "LegacyExternalAPIServerComponentsOnly" and "StrictAllComponents".

When set to "LegacyExternalAPIServerComponentsOnly", only the externally exposed
API server components (kube-apiserver, openshift-apiserver, oauth-apiserver) honor the configured
TLS profile. Other components continue to use their individual TLS configurations.

When set to "StrictAllComponents", all components must honor the configured TLS profile
unless they have a component-specific TLS configuration that overrides it.
This mode is recommended for security-conscious deployments and is required for
certain compliance frameworks.

Note: Some components such as Kubelet and IngressController have their own dedicated TLS
configuration mechanisms via KubeletConfig and IngressController CRs respectively. When these
component-specific TLS configurations are set, they take precedence over the cluster-wide
tlsSecurityProfile. When not set, these components fall back to the cluster-wide default.

Components that encounter an unknown value for tlsAdherence should treat it as "StrictAllComponents"
and log a warning to ensure forward compatibility while defaulting to the more secure behavior.

This field is optional.
When omitted, this means the user has no opinion and the platform is left to choose reasonable defaults.
These defaults are subject to change over time.
The current default is LegacyExternalAPIServerComponentsOnly.

Once set, this field may be changed to a different value, but may not be removed.
enum:
- LegacyExternalAPIServerComponentsOnly
- StrictAllComponents
type: string
tlsSecurityProfile:
description: |-
tlsSecurityProfile specifies settings for TLS connections for externally exposed servers.
Expand Down Expand Up @@ -359,6 +393,9 @@ spec:
type: string
type: object
type: object
x-kubernetes-validations:
- message: tlsAdherence may not be removed once set
rule: 'has(oldSelf.tlsAdherence) ? has(self.tlsAdherence) : true'
status:
description: status holds observed values from the cluster. They may not
be overridden.
Expand Down
1 change: 1 addition & 0 deletions config/v1/zz_generated.featuregated-crd-manifests.yaml
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Expand Up @@ -8,6 +8,7 @@ apiservers.config.openshift.io:
FeatureGates:
- KMSEncryption
- KMSEncryptionProvider
- TLSAdherence
FilenameOperatorName: config-operator
FilenameOperatorOrdering: "01"
FilenameRunLevel: "0000_10"
Expand Down
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