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Kubernetes Ingress Controller annotations

The Kubernetes Ingress Controller supports the following annotations on various resources:

Ingress resource

Following annotations are supported on Ingress resources:

kubernetes.io/ingress.class is normally required, and its value should match the value of the --ingress-class controller argument (“kong” by default).

Setting the --process-classless-ingress-v1beta1 controller flag removes that requirement: when enabled, the controller will process Ingresses with no kubernetes.io/ingress.class annotation. Recommended best practice is to set the annotation and leave this flag disabled; the flag is intended for older configurations, as controller versions prior to 0.10 processed classless Ingress resources by default.

Service resource

Following annotations are supported on Service resources:

KongConsumer resource

Following annotaitons are supported on KongConsumer resources:

kubernetes.io/ingress.class is normally required, and its value should match the value of the --ingress-class controller argument (“kong” by default).

Setting the --process-classless-kong-consumer controller flag removes that requirement: when enabled, the controller will process KongConsumers with no kubernetes.io/ingress.class annotation. Recommended best practice is to set the annotation and leave this flag disabled; the flag is primarily intended for older configurations, as controller versions prior to 0.10 processed classless KongConsumer resources by default.

Annotations

kubernetes.io/ingress.class

If you have multiple Ingress controllers in a single cluster, you can pick one by specifying the ingress.class annotation. Following is an example of creating an Ingress with an annotation:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: test-1
  annotations:
    kubernetes.io/ingress.class: "gce"
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /test1
        backend:
          serviceName: echo
          servicePort: 80

This will target the GCE controller, forcing the Kubernetes Ingress Controller to ignore it.

On the other hand, an annotation such as

metadata:
  name: test-1
  annotations:
    kubernetes.io/ingress.class: "kong"

will target the Kubernetes Ingress Controller, forcing the GCE controller to ignore it.

The following resources require this annotation by default:

• Ingress
• KongConsumer
• TCPIngress
• KongClusterPlugin
• Secret resources with the ca-cert label

You can optionally allow Ingress or KongConsumer resources with no class annotation (by setting the --process-classless-ingress-v1beta1 or --process-classless-kong-consumer flags, respectively), though recommended best practice is to leave these flags disabled: the flags are primarily intended for compatibility with configuration created before this requirement was introduced in controller 0.10.

If you allow classless resources, you must take care when using multiple controller instances in a single cluster: only one controller instance should enable these flags to avoid different controller instances fighting over classless resources, which will result in unexpected and unknown behavior.

The ingress class used by the Kubernetes Ingress Controller to filter Ingress resources can be changed using the CONTROLLER_INGRESS_CLASS environment variable.

spec:
  template:
     spec:
       containers:
         - name: kong-ingress-internal-controller
           env:
           - name: CONTROLLER_INGRESS_CLASS
             value: kong-internal

Multiple unrelated Kubernetes Ingress Controllers

In some deployments, one might use multiple Kubernetes Ingress Controllers in the same Kubernetes cluster (e.g. one which serves public traffic, one which serves “internal” traffic). For such deployments, please ensure that in addition to different ingress-class, the --election-id is also different.

In such deployments, kubernetes.io/ingress.class annotation can be used on the following custom resources as well:

• KongPlugin: To configure (global) plugins only in one of the Kong clusters.
• KongConsumer: To create different consumers in different Kong clusters.
• KongCredential: To create associated credentials for consumers.

konghq.com/plugins

Available since controller 0.8

Kong’s power comes from its plugin architecture, where plugins can modify the request and response or impose certain policies on the requests as they are proxied to your service.

With the Kubernetes Ingress Controller, plugins can be configured by creating KongPlugin Custom Resources and then associating them with an Ingress, Service, KongConsumer or a combination of those.

Following is an example of how to use the annotation:

konghq.com/plugins: high-rate-limit, docs-site-cors

Here, high-rate-limit and docs-site-cors are the names of the KongPlugin resources which should be to be applied to the Ingress rules defined in the Ingress resource on which the annotation is being applied.

This annotation can also be applied to a Service resource in Kubernetes, which will result in the plugin being executed at Service-level in Kong, meaning the plugin will be executed for every request that is proxied, no matter which Route it came from.

This annotation can also be applied to a KongConsumer resource, which results in plugin being executed whenever the specific consumer is accessing any of the defined APIs.

Finally, this annotation can also be applied on a combination of the following resources:

• Ingress and KongConsumer
  If an Ingress resource and a KongConsumer resource share a plugin in the konghq.com/plugins annotation then the plugin will be created for the combination of those to resources in Kong.
• Service and KongConsumer
  Same as the above case, if you would like to give a specific consumer or client of your service some special treatment, you can do so by applying the same annotation to both of the resources.

Please follow the Using the KongPlugin resource guide for details on how this annotation can be used.

konghq.com/path

Available since controller 0.8

This annotation can be used on a Service resource only. This annotation can be used to prepend an HTTP path of a request, before the request is forwarded.

For example, if the annotation konghq.com/path: "/baz" is applied to a Kubernetes Service billings, then any request that is routed to the billings service will be prepended with /baz HTTP path. If the request contains /foo/something as the path, then the service will receive an HTTP request with path set as /baz/foo/something.

konghq.com/strip-path

Available since controller 0.8

This annotation can be applied to an Ingress resource and can take two values:

• "true": If set to true, the part of the path specified in the Ingress rule will be stripped out before the request is sent to the service. For example, if the Ingress rule has a path of /foo and the HTTP request that matches the Ingress rule has the path /foo/bar/something, then the request sent to the Kubernetes service will have the path /bar/something.
• "false": If set to false, no path manipulation is performed.

All other values are ignored. Please note the quotes (") around the boolean value.

Sample usage:

konghq.com/strip-path: "true"

konghq.com/preserve-host

Available since controller 0.8

This annotation can be applied to an Ingress resource and can take two values:

• "true": If set to true, the host header of the request will be sent as is to the Service in Kubernetes.
• "false": If set to false, the host header of the request is not preserved.

Please note the quotes (") around the boolean value.

Sample usage:

konghq.com/preserve-host: "true"

konghq.com/https-redirect-status-code

Available since controller 0.8

By default, Kong sends HTTP Status Code 426 for requests that need to be redirected to HTTPS. This can be changed using this annotations. Acceptable values are:

• 301
• 302
• 307
• 308
• 426

Any other value will be ignored.

Sample usage:

konghq.com/https-redirect-status-code: "301"

Please note the quotes (") around the integer value.

konghq.com/regex-priority

Available since controller 0.9

Sets the regex_priority setting to this value on the Kong route associated with the Ingress resource. This controls the matching evaluation order for regex-based routes. It accepts any integer value. Routes are evaluated in order of highest priority to lowest.

Sample usage:

konghq.com/regex-priority: "10"

Please note the quotes (") around the integer value.

konghq.com/methods

Available since controller 0.9

Sets the methods setting on the Kong route associated with the Ingress resource. This controls which request methods will match the route. Any uppercase alpha ASCII string is accepted, though most users will use only standard methods.

Sample usage:

konghq.com/methods: "GET,POST"

konghq.com/snis

Available since controller 1.1

Sets the snis match criteria on the Kong route associated with this Ingress. When using route-attached plugins that execute during the certificate phase (for example, Mutual TLS Authentication), the snis annotation allows route matching based on the server name indication information sent in a client’s TLS handshake.

Sample usage:

konghq.com/snis: "foo.example.com, bar.example.com"

konghq.com/request-buffering

Available since controller 1.2

Enables or disables request buffering on the Kong route associated with this Ingress.

Sample usage:

konghq.com/request-buffering: "false"

konghq.com/response-buffering

Available since controller 1.2

Enables or disables response buffering on the Kong route associated with this Ingress.

Sample usage:

konghq.com/response-buffering: "false"

konghq.com/override

Available since controller 0.8

This annotation can associate a KongIngress resource with an Ingress or a Service resource. It serves as a way to bridge the gap between a sparse Ingress API in Kubernetes with fine-grained controlled using the properties of Service, Route and Upstream entities in Kong.

Please follow the Using the KongIngress resource guide for details on how to use this annotation.

konghq.com/protocol

Available since controller 0.8

This annotation can be set on a Kubernetes Service resource and indicates the protocol that should be used by Kong to communicate with the service. In other words, the protocol is used for communication between a Kong Service and a Kubernetes Service, internally in the Kubernetes cluster.

Accepted values are:

• http
• https
• grpc
• grpcs
• tcp
• tls

konghq.com/protocols

Available since controller 0.8

This annotation sets the list of acceptable protocols for the all the rules defined in the Ingress resource. The protocols are used for communication between the Kong and the external client/user of the Service.

You usually want to set this annotation for the following two use-cases:

• You want to redirect HTTP traffic to HTTPS, in which case you will use konghq.com/protocols: "https"
• You want to define gRPC routing, in which case you should use konghq.com/protocols: "grpc,grpcs"

konghq.com/client-cert

Available since controller 0.8

This annotation sets the certificate and key-pair Kong should use to authenticate itself against the upstream service, if the upstream service is performing mutual-TLS (mTLS) authentication.

The value of this annotation should be the name of the Kubernetes TLS Secret resource which contains the TLS cert and key pair.

Under the hood, the controller creates a Certificate in Kong and then sets the service.client_certificate for the service.

konghq.com/host-header

Available since controller 0.9

Sets the host_header setting on the Kong upstream created to represent a Kubernetes Service. By default, Kong upstreams set Host to the hostname or IP address of an individual target (the Pod IP for controller-managed configuration). This annotation overrides the default behavior and sends the annotation value as the Host header value.

If konghq.com/preserve-host: true is present on an Ingress (or route.preserve_host: true is present in a linked KongIngress), it will take precedence over this annotation, and requests to the application will use the hostname in the Ingress rule.

Sample usage:

konghq.com/host-header: "test.example.com"

ingress.kubernetes.io/service-upstream

By default, the Kubernetes Ingress Controller distributes traffic amongst all the Pods of a Kubernetes Service by forwarding the requests directly to Pod IP addresses. One can choose the load-balancing strategy to use by specifying a KongIngress resource.

However, in some use-cases, the load-balancing should be left up to kube-proxy, or a sidecar component in the case of Service Mesh deployments.

Setting this annotation to a Service resource in Kubernetes will configure the Kubernetes Ingress Controller to directly forward the traffic outbound for this Service to the IP address of the service (usually the ClusterIP).

kube-proxy can then decide how it wants to handle the request and route the traffic accordingly. If a sidecar intercepts the traffic from the controller, it can also route traffic as it sees fit in this case.

Following is an example snippet you can use to configure this annotation on a Service resource in Kubernetes, (please note the quotes around true):

annotations:
  ingress.kubernetes.io/service-upstream: "true"

You need Kubernetes Ingress Controller >= 0.6 for this annotation.