kube-apiserver Configuration (v1)

Endpoint of the collector this component will report traces to. The connection is insecure, and does not currently support TLS. Recommended is unset, and endpoint is the otlp grpc default, localhost:4317.

SamplingRatePerMillion is the number of samples to collect per million spans. Recommended is unset. If unset, sampler respects its parent span's sampling rate, but otherwise never samples.

Plugins allows specifying a configuration per admission control plugin.

jwt is a list of authenticator to authenticate Kubernetes users using JWT compliant tokens. The authenticator will attempt to parse a raw ID token, verify it's been signed by the configured issuer. The public key to verify the signature is discovered from the issuer's public endpoint using OIDC discovery. For an incoming token, each JWT authenticator will be attempted in the order in which it is specified in this list. Note however that other authenticators may run before or after the JWT authenticators. The specific position of JWT authenticators in relation to other authenticators is neither defined nor stable across releases. Since each JWT authenticator must have a unique issuer URL, at most one JWT authenticator will attempt to cryptographically validate the token.

The minimum valid JWT payload must contain the following claims: { "iss": "https://issuer.example.com", "aud": ["audience"], "exp": 1234567890, "": "username" }

If present --anonymous-auth must not be set

Authorizers is an ordered list of authorizers to authorize requests against. This is similar to the --authorization-modes kube-apiserver flag Must be at least one.

resources is a list containing resources, and their corresponding encryption providers.

Embed the component config tracing configuration struct

keys is a list of keys to be used for creating the AES transformer. Each key has to be 32 bytes long for AES-CBC and 16, 24 or 32 bytes for AES-GCM.

Name is the name of the admission controller. It must match the registered admission plugin name.

Path is the path to a configuration file that contains the plugin's configuration

Configuration is an embedded configuration object to be used as the plugin's configuration. If present, it will be used instead of the path to the configuration file.

Path for which anonymous auth is enabled.

If set, anonymous auth is only allowed if the request meets one of the conditions.

Type refers to the type of the authorizer "Webhook" is supported in the generic API server Other API servers may support additional authorizer types like Node, RBAC, ABAC, etc.

Name used to describe the webhook This is explicitly used in monitoring machinery for metrics Note: Names must be DNS1123 labels like myauthorizername or subdomains like myauthorizer.example.domain Required, with no default

Webhook defines the configuration for a Webhook authorizer Must be defined when Type=Webhook Must not be defined when Type!=Webhook

username represents an option for the username attribute. The claim's value must be a singular string. Same as the --oidc-username-claim and --oidc-username-prefix flags. If username.expression is set, the expression must produce a string value. If username.expression uses 'claims.email', then 'claims.email_verified' must be used in username.expression or extra[].valueExpression or claimValidationRules[].expression. An example claim validation rule expression that matches the validation automatically applied when username.claim is set to 'email' is 'claims.?email_verified.orValue(true) == true'. By explicitly comparing the value to true, we let type-checking see the result will be a boolean, and to make sure a non-boolean email_verified claim will be caught at runtime.

In the flag based approach, the --oidc-username-claim and --oidc-username-prefix are optional. If --oidc-username-claim is not set, the default value is "sub". For the authentication config, there is no defaulting for claim or prefix. The claim and prefix must be set explicitly. For claim, if --oidc-username-claim was not set with legacy flag approach, configure username.claim="sub" in the authentication config. For prefix: (1) --oidc-username-prefix="-", no prefix was added to the username. For the same behavior using authentication config, set username.prefix="" (2) --oidc-username-prefix="" and --oidc-username-claim != "email", prefix was "<value of --oidc-issuer-url>#". For the same behavior using authentication config, set username.prefix="#" (3) --oidc-username-prefix="". For the same behavior using authentication config, set username.prefix=""

groups represents an option for the groups attribute. The claim's value must be a string or string array claim. If groups.claim is set, the prefix must be specified (and can be the empty string). If groups.expression is set, the expression must produce a string or string array value. "", [], and null values are treated as the group mapping not being present.

uid represents an option for the uid attribute. Claim must be a singular string claim. If uid.expression is set, the expression must produce a string value.

extra represents an option for the extra attribute. expression must produce a string or string array value. If the value is empty, the extra mapping will not be present.

hard-coded extra key/value

• key: "foo" valueExpression: "'bar'" This will result in an extra attribute - foo: ["bar"]

hard-coded key, value copying claim value

• key: "foo" valueExpression: "claims.some_claim" This will result in an extra attribute - foo: [value of some_claim]

hard-coded key, value derived from claim value

• key: "admin" valueExpression: '(has(claims.is_admin) && claims.is_admin) ? "true":""' This will result in:
• if is_admin claim is present and true, extra attribute - admin: ["true"]
• if is_admin claim is present and false or is_admin claim is not present, no extra attribute will be added

claim is the JWT claim to use. Either claim or expression must be set. Mutually exclusive with expression.

expression represents the expression which will be evaluated by CEL.

CEL expressions have access to the contents of the token claims, organized into CEL variable:

• 'claims' is a map of claim names to claim values. For example, a variable named 'sub' can be accessed as 'claims.sub'. Nested claims can be accessed using dot notation, e.g. 'claims.foo.bar'.

Documentation on CEL: https://kubernetes.io/docs/reference/using-api/cel/

Mutually exclusive with claim.

claim is the name of a required claim. Same as --oidc-required-claim flag. Only string claim keys are supported. Mutually exclusive with expression and message.

requiredValue is the value of a required claim. Same as --oidc-required-claim flag. Only string claim values are supported. If claim is set and requiredValue is not set, the claim must be present with a value set to the empty string. Mutually exclusive with expression and message.

expression represents the expression which will be evaluated by CEL. Must produce a boolean.

CEL expressions have access to the contents of the token claims, organized into CEL variable:

• 'claims' is a map of claim names to claim values. For example, a variable named 'sub' can be accessed as 'claims.sub'. Nested claims can be accessed using dot notation, e.g. 'claims.foo.bar'. Must return true for the validation to pass.

Documentation on CEL: https://kubernetes.io/docs/reference/using-api/cel/

Mutually exclusive with claim and requiredValue.

message customizes the returned error message when expression returns false. message is a literal string. Mutually exclusive with claim and requiredValue.

key is a string to use as the extra attribute key. key must be a domain-prefix path (e.g. example.org/foo). All characters before the first "/" must be a valid subdomain as defined by RFC 1123. All characters trailing the first "/" must be valid HTTP Path characters as defined by RFC 3986. key must be lowercase. Required to be unique.

valueExpression is a CEL expression to extract extra attribute value. valueExpression must produce a string or string array value. "", [], and null values are treated as the extra mapping not being present. Empty string values contained within a string array are filtered out.

CEL expressions have access to the contents of the token claims, organized into CEL variable:

• 'claims' is a map of claim names to claim values. For example, a variable named 'sub' can be accessed as 'claims.sub'. Nested claims can be accessed using dot notation, e.g. 'claims.foo.bar'.

Documentation on CEL: https://kubernetes.io/docs/reference/using-api/cel/

url points to the issuer URL in a format https://url or https://url/path. This must match the "iss" claim in the presented JWT, and the issuer returned from discovery. Same value as the --oidc-issuer-url flag. Discovery information is fetched from "{url}/.well-known/openid-configuration" unless overridden by discoveryURL. Required to be unique across all JWT authenticators. Note that egress selection configuration is not used for this network connection.

discoveryURL, if specified, overrides the URL used to fetch discovery information instead of using "{url}/.well-known/openid-configuration". The exact value specified is used, so "/.well-known/openid-configuration" must be included in discoveryURL if needed.

The "issuer" field in the fetched discovery information must match the "issuer.url" field in the AuthenticationConfiguration and will be used to validate the "iss" claim in the presented JWT. This is for scenarios where the well-known and jwks endpoints are hosted at a different location than the issuer (such as locally in the cluster).

Example: A discovery url that is exposed using kubernetes service 'oidc' in namespace 'oidc-namespace' and discovery information is available at '/.well-known/openid-configuration'. discoveryURL: "https://oidc.oidc-namespace/.well-known/openid-configuration" certificateAuthority is used to verify the TLS connection and the hostname on the leaf certificate must be set to 'oidc.oidc-namespace'.

curl https://oidc.oidc-namespace/.well-known/openid-configuration (.discoveryURL field) { issuer: "https://oidc.example.com" (.url field) }

discoveryURL must be different from url. Required to be unique across all JWT authenticators. Note that egress selection configuration is not used for this network connection.

certificateAuthority contains PEM-encoded certificate authority certificates used to validate the connection when fetching discovery information. If unset, the system verifier is used. Same value as the content of the file referenced by the --oidc-ca-file flag.

audiences is the set of acceptable audiences the JWT must be issued to. At least one of the entries must match the "aud" claim in presented JWTs. Same value as the --oidc-client-id flag (though this field supports an array). Required to be non-empty.

audienceMatchPolicy defines how the "audiences" field is used to match the "aud" claim in the presented JWT. Allowed values are:

1. "MatchAny" when multiple audiences are specified and
2. empty (or unset) or "MatchAny" when a single audience is specified.

• MatchAny: the "aud" claim in the presented JWT must match at least one of the entries in the "audiences" field. For example, if "audiences" is ["foo", "bar"], the "aud" claim in the presented JWT must contain either "foo" or "bar" (and may contain both).

• "": The match policy can be empty (or unset) when a single audience is specified in the "audiences" field. The "aud" claim in the presented JWT must contain the single audience (and may contain others).

For more nuanced audience validation, use claimValidationRules. example: claimValidationRule[].expression: 'sets.equivalent(claims.aud, ["bar", "foo", "baz"])' to require an exact match.

egressSelectorType is an indicator of which egress selection should be used for sending all traffic related to this issuer (discovery, JWKS, distributed claims, etc). If unspecified, no custom dialer is used. When specified, the valid choices are "controlplane" and "cluster". These correspond to the associated values in the --egress-selector-config-file.

• controlplane: for traffic intended to go to the control plane.

• cluster: for traffic intended to go to the system being managed by Kubernetes.

issuer contains the basic OIDC provider connection options.

claimValidationRules are rules that are applied to validate token claims to authenticate users.

claimMappings points claims of a token to be treated as user attributes.

userValidationRules are rules that are applied to final user before completing authentication. These allow invariants to be applied to incoming identities such as preventing the use of the system: prefix that is commonly used by Kubernetes components. The validation rules are logically ANDed together and must all return true for the validation to pass.

apiVersion of KeyManagementService

name is the name of the KMS plugin to be used.

cachesize is the maximum number of secrets which are cached in memory. The default value is 1000. Set to a negative value to disable caching. This field is only allowed for KMS v1 providers.

endpoint is the gRPC server listening address, for example "unix:///var/run/kms-provider.sock".

timeout for gRPC calls to kms-plugin (ex. 5s). The default is 3 seconds.

name is the name of the key to be used while storing data to disk.

secret is the actual key, encoded in base64.

claim is the JWT claim to use. Mutually exclusive with expression.

prefix is prepended to claim's value to prevent clashes with existing names. prefix needs to be set if claim is set and can be the empty string. Mutually exclusive with expression.

expression represents the expression which will be evaluated by CEL.

CEL expressions have access to the contents of the token claims, organized into CEL variable:

• 'claims' is a map of claim names to claim values. For example, a variable named 'sub' can be accessed as 'claims.sub'. Nested claims can be accessed using dot notation, e.g. 'claims.foo.bar'.

Documentation on CEL: https://kubernetes.io/docs/reference/using-api/cel/

Mutually exclusive with claim and prefix.

aesgcm is the configuration for the AES-GCM transformer.

aescbc is the configuration for the AES-CBC transformer.

secretbox is the configuration for the Secretbox based transformer.

identity is the (empty) configuration for the identity transformer.

kms contains the name, cache size and path to configuration file for a KMS based envelope transformer.

resources is a list of kubernetes resources which have to be encrypted. The resource names are derived from resource or resource.group of the group/version/resource. eg: pandas.awesome.bears.example is a custom resource with 'group': awesome.bears.example, 'resource': pandas. Use '.' to encrypt all resources and '.' to encrypt all resources in a specific group. eg: '.awesome.bears.example' will encrypt all resources in the group 'awesome.bears.example'. eg: '*.' will encrypt all resources in the core group (such as pods, configmaps, etc).

providers is a list of transformers to be used for reading and writing the resources to disk. eg: aesgcm, aescbc, secretbox, identity, kms.

keys is a list of keys to be used for creating the Secretbox transformer. Each key has to be 32 bytes long.

expression represents the expression which will be evaluated by CEL. Must return true for the validation to pass.

CEL expressions have access to the contents of UserInfo, organized into CEL variable:

• 'user' - authentication.k8s.io/v1, Kind=UserInfo object Refer to https://github.com/kubernetes/api/blob/release-1.28/authentication/v1/types.go#L105-L122 for the definition. API documentation: https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.28/#userinfo-v1-authentication-k8s-io

Documentation on CEL: https://kubernetes.io/docs/reference/using-api/cel/

message customizes the returned error message when rule returns false. message is a literal string.

The duration to cache 'authorized' responses from the webhook authorizer. Same as setting --authorization-webhook-cache-authorized-ttl flag Default: 5m0s

CacheAuthorizedRequests specifies whether authorized requests should be cached. If set to true, the TTL for cached decisions can be configured via the AuthorizedTTL field. Default: true

The duration to cache 'unauthorized' responses from the webhook authorizer. Same as setting --authorization-webhook-cache-unauthorized-ttl flag Default: 30s

CacheUnauthorizedRequests specifies whether unauthorized requests should be cached. If set to true, the TTL for cached decisions can be configured via the UnauthorizedTTL field. Default: true

Timeout for the webhook request Maximum allowed value is 30s. Required, no default value.

The API version of the authorization.k8s.io SubjectAccessReview to send to and expect from the webhook. Same as setting --authorization-webhook-version flag Valid values: v1beta1, v1 Required, no default value

MatchConditionSubjectAccessReviewVersion specifies the SubjectAccessReview version the CEL expressions are evaluated against Valid values: v1 Required, no default value

Controls the authorization decision when a webhook request fails to complete or returns a malformed response or errors evaluating matchConditions. Valid values:

• NoOpinion: continue to subsequent authorizers to see if one of them allows the request
• Deny: reject the request without consulting subsequent authorizers Required, with no default.

ConnectionInfo defines how we talk to the webhook

matchConditions is a list of conditions that must be met for a request to be sent to this webhook. An empty list of matchConditions matches all requests. There are a maximum of 64 match conditions allowed.

The exact matching logic is (in order):

1. If at least one matchCondition evaluates to FALSE, then the webhook is skipped.
2. If ALL matchConditions evaluate to TRUE, then the webhook is called.
3. If at least one matchCondition evaluates to an error (but none are FALSE):
   • If failurePolicy=Deny, then the webhook rejects the request
   • If failurePolicy=NoOpinion, then the error is ignored and the webhook is skipped

Controls how the webhook should communicate with the server. Valid values:

• KubeConfigFile: use the file specified in kubeConfigFile to locate the server.
• InClusterConfig: use the in-cluster configuration to call the SubjectAccessReview API hosted by kube-apiserver. This mode is not allowed for kube-apiserver.

Path to KubeConfigFile for connection info Required, if connectionInfo.Type is KubeConfig

expression represents the expression which will be evaluated by CEL. Must evaluate to bool. CEL expressions have access to the contents of the SubjectAccessReview in v1 version. If version specified by subjectAccessReviewVersion in the request variable is v1beta1, the contents would be converted to the v1 version before evaluating the CEL expression.

• 'resourceAttributes' describes information for a resource access request and is unset for non-resource requests. e.g. has(request.resourceAttributes) && request.resourceAttributes.namespace == 'default'
• 'nonResourceAttributes' describes information for a non-resource access request and is unset for resource requests. e.g. has(request.nonResourceAttributes) && request.nonResourceAttributes.path == '/healthz'.
• 'user' is the user to test for. e.g. request.user == 'alice'
• 'groups' is the groups to test for. e.g. ('group1' in request.groups)
• 'extra' corresponds to the user.Info.GetExtra() method from the authenticator.
• 'uid' is the information about the requesting user. e.g. request.uid == '1'

Documentation on CEL: https://kubernetes.io/docs/reference/using-api/cel/