backendtlspolicy_types.go

/*
Copyright 2023 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package v1alpha3

import (
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	v1 "sigs.k8s.io/gateway-api/apis/v1"
	"sigs.k8s.io/gateway-api/apis/v1alpha2"
)

// +genclient
// +kubebuilder:object:root=true
// +kubebuilder:subresource:status
// +kubebuilder:storageversion
// +kubebuilder:resource:categories=gateway-api,shortName=btlspolicy
// +kubebuilder:printcolumn:name="Age",type=date,JSONPath=`.metadata.creationTimestamp`
//
// BackendTLSPolicy is a Direct Attached Policy.
// +kubebuilder:metadata:labels="gateway.networking.k8s.io/policy=Direct"

// BackendTLSPolicy provides a way to configure how a Gateway
// connects to a Backend via TLS.
type BackendTLSPolicy struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`

	// Spec defines the desired state of BackendTLSPolicy.
	Spec BackendTLSPolicySpec `json:"spec"`

	// Status defines the current state of BackendTLSPolicy.
	Status v1alpha2.PolicyStatus `json:"status,omitempty"`
}

// BackendTLSPolicyList contains a list of BackendTLSPolicies
// +kubebuilder:object:root=true
type BackendTLSPolicyList struct {
	metav1.TypeMeta `json:",inline"`
	metav1.ListMeta `json:"metadata,omitempty"`
	Items           []BackendTLSPolicy `json:"items"`
}

// BackendTLSPolicySpec defines the desired state of BackendTLSPolicy.
//
// Support: Extended
type BackendTLSPolicySpec struct {
	// TargetRefs identifies an API object to apply the policy to.
	// Only Services have Extended support. Implementations MAY support
	// additional objects, with Implementation Specific support.
	// Note that this config applies to the entire referenced resource
	// by default, but this default may change in the future to provide
	// a more granular application of the policy.
	//
	// Support: Extended for Kubernetes Service
	//
	// Support: Implementation-specific for any other resource
	//
	// +kubebuilder:validation:MinItems=1
	// +kubebuilder:validation:MaxItems=16
	TargetRefs []v1alpha2.LocalPolicyTargetReferenceWithSectionName `json:"targetRefs"`

	// Validation contains backend TLS validation configuration.
	Validation BackendTLSPolicyValidation `json:"validation"`

	// Options are a list of key/value pairs to enable extended TLS
	// configuration for each implementation. For example, configuring the
	// minimum TLS version or supported cipher suites.
	//
	// A set of common keys MAY be defined by the API in the future. To avoid
	// any ambiguity, implementation-specific definitions MUST use
	// domain-prefixed names, such as `example.com/my-custom-option`.
	// Un-prefixed names are reserved for key names defined by Gateway API.
	//
	// Support: Implementation-specific
	//
	// +optional
	// +kubebuilder:validation:MaxProperties=16
	Options map[v1.AnnotationKey]v1.AnnotationValue `json:"options,omitempty"`
}

// BackendTLSPolicyValidation contains backend TLS validation configuration.
// +kubebuilder:validation:XValidation:message="must not contain both CACertificateRefs and WellKnownCACertificates",rule="!(has(self.caCertificateRefs) && size(self.caCertificateRefs) > 0 && has(self.wellKnownCACertificates) && self.wellKnownCACertificates != \"\")"
// +kubebuilder:validation:XValidation:message="must specify either CACertificateRefs or WellKnownCACertificates",rule="(has(self.caCertificateRefs) && size(self.caCertificateRefs) > 0 || has(self.wellKnownCACertificates) && self.wellKnownCACertificates != \"\")"
type BackendTLSPolicyValidation struct {
	// CACertificateRefs contains one or more references to Kubernetes objects that
	// contain a PEM-encoded TLS CA certificate bundle, which is used to
	// validate a TLS handshake between the Gateway and backend Pod.
	//
	// If CACertificateRefs is empty or unspecified, then WellKnownCACertificates must be
	// specified. Only one of CACertificateRefs or WellKnownCACertificates may be specified,
	// not both. If CACertifcateRefs is empty or unspecified, the configuration for
	// WellKnownCACertificates MUST be honored instead if supported by the implementation.
	//
	// References to a resource in a different namespace are invalid for the
	// moment, although we will revisit this in the future.
	//
	// A single CACertificateRef to a Kubernetes ConfigMap kind has "Core" support.
	// Implementations MAY choose to support attaching multiple certificates to
	// a backend, but this behavior is implementation-specific.
	//
	// Support: Core - An optional single reference to a Kubernetes ConfigMap,
	// with the CA certificate in a key named `ca.crt`.
	//
	// Support: Implementation-specific (More than one reference, or other kinds
	// of resources).
	//
	// +kubebuilder:validation:MaxItems=8
	// +optional
	CACertificateRefs []v1.LocalObjectReference `json:"caCertificateRefs,omitempty"`

	// WellKnownCACertificates specifies whether system CA certificates may be used in
	// the TLS handshake between the gateway and backend pod.
	//
	// If WellKnownCACertificates is unspecified or empty (""), then CACertificateRefs
	// must be specified with at least one entry for a valid configuration. Only one of
	// CACertificateRefs or WellKnownCACertificates may be specified, not both. If an
	// implementation does not support the WellKnownCACertificates field or the value
	// supplied is not supported, the Status Conditions on the Policy MUST be
	// updated to include an Accepted: False Condition with Reason: Invalid.
	//
	// Support: Implementation-specific
	//
	// +optional
	WellKnownCACertificates *WellKnownCACertificatesType `json:"wellKnownCACertificates,omitempty"`

	// Hostname is used for two purposes in the connection between Gateways and
	// backends:
	//
	// 1. Hostname MUST be used as the SNI to connect to the backend (RFC 6066).
	// 2. If SubjectAltNames is not specified, Hostname MUST be used for
	//    authentication and MUST match the certificate served by the matching
	//    backend.
	//
	// Support: Core
	Hostname v1.PreciseHostname `json:"hostname"`

	// SubjectAltNames contains one or more Subject Alternative Names.
	// When specified, the certificate served from the backend MUST have at least one
	// Subject Alternate Name matching one of the specified SubjectAltNames.
	//
	// Support: Core
	//
	// +optional
	// +kubebuilder:validation:MaxItems=5
	SubjectAltNames []SubjectAltName `json:"subjectAltNames,omitempty"`
}

// SubjectAltName represents Subject Alternative Name.
// +kubebuilder:validation:XValidation:message="SubjectAltName element must contain Hostname, if Type is set to Hostname",rule="!(self.type == \"Hostname\" && (!has(self.hostname) || self.hostname == \"\"))"
// +kubebuilder:validation:XValidation:message="SubjectAltName element must not contain Hostname, if Type is not set to Hostname",rule="!(self.type != \"Hostname\" && has(self.hostname) && self.hostname != \"\")"
// +kubebuilder:validation:XValidation:message="SubjectAltName element must contain URI, if Type is set to URI",rule="!(self.type == \"URI\" && (!has(self.uri) || self.uri == \"\"))"
// +kubebuilder:validation:XValidation:message="SubjectAltName element must not contain URI, if Type is not set to URI",rule="!(self.type != \"URI\" && has(self.uri) && self.uri != \"\")"
type SubjectAltName struct {
	// Type determines the format of the Subject Alternative Name. Always required.
	//
	// Support: Core
	Type SubjectAltNameType `json:"type"`

	// Hostname contains Subject Alternative Name specified in DNS name format.
	// Required when Type is set to Hostname, ignored otherwise.
	//
	// Support: Core
	//
	// +optional
	Hostname v1.Hostname `json:"hostname,omitempty"`

	// URI contains Subject Alternative Name specified in a full URI format.
	// It MUST include both a scheme (e.g., "http" or "ftp") and a scheme-specific-part.
	// Common values include SPIFFE IDs like "spiffe://mycluster.example.com/ns/myns/sa/svc1sa".
	// Required when Type is set to URI, ignored otherwise.
	//
	// Support: Core
	//
	// +optional
	URI v1.AbsoluteURI `json:"uri,omitempty"`
}

// WellKnownCACertificatesType is the type of CA certificate that will be used
// when the caCertificateRefs field is unspecified.
// +kubebuilder:validation:Enum=System
type WellKnownCACertificatesType string

const (
	// WellKnownCACertificatesSystem indicates that well known system CA certificates should be used.
	WellKnownCACertificatesSystem WellKnownCACertificatesType = "System"
)

// SubjectAltNameType is the type of the Subject Alternative Name.
// +kubebuilder:validation:Enum=Hostname;URI
type SubjectAltNameType string

const (
	// HostnameSubjectAltNameType specifies hostname-based SAN.
	//
	// Support: Core
	HostnameSubjectAltNameType SubjectAltNameType = "Hostname"

	// URISubjectAltNameType specifies URI-based SAN, e.g. SPIFFE id.
	//
	// Support: Core
	URISubjectAltNameType SubjectAltNameType = "URI"
)