kubernetes

Documentation

Overview

Package kubernetes implements Kubernetes Ingress support for Skipper.

See: http://kubernetes.io/docs/user-guide/ingress/

The package provides a Skipper DataClient implementation that can be used to access the Kubernetes API for ingress resources and generate routes based on them. The client polls for the ingress settings, and there is no need for a separate controller. On the other hand, it doesn't provide a full Ingress solution alone, because it doesn't do any load balancer configuration or DNS updates. For a full Ingress solution, it is possible to use Skipper together with Kube-ingress-aws-controller, which targets AWS and takes care of the load balancer setup for Kubernetes Ingress.

See: https://github.com/zalando-incubator/kube-ingress-aws-controller

Both Kube-ingress-aws-controller and Skipper Kubernetes are part of the larger project, Kubernetes On AWS:

https://github.com/zalando-incubator/kubernetes-on-aws/

Ingress shutdown by healthcheck

The Kubernetes ingress client catches TERM signals when the ProvideHealthcheck option is enabled, and reports failing healthcheck after the signal was received. This means that, when the Ingress client is responsible for the healthcheck of the cluster, and the Skipper process receives the TERM signal, it won't exit by itself immediately, but will start reporting failures on healthcheck requests. Until it gets killed by the kubelet, Skipper keeps serving the requests in this case.

Example - Ingress

A basic ingress specification:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Example - Ingress with ratelimiting

The example shows 50 calls per minute are allowed to each skipper instance for the given ingress.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/ratelimit: ratelimit(50, "1m")
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Example - Ingress with client based ratelimiting

The example shows 3 calls per minute per client, based on X-Forwarded-For header or IP incase there is no X-Forwarded-For header set, are allowed to each skipper instance for the given ingress.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/ratelimit: localRatelimit(3, "1m")
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

The example shows 500 calls per hour per client, based on Authorization header set, are allowed to each skipper instance for the given ingress.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/ratelimit: localRatelimit(500, "1h", "auth")
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Example - Ingress with custom skipper filter configuration

The example shows the use of 2 filters from skipper for the implicitly defined route in ingress.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/skipper-filter: localRatelimit(50, "10m") -> requestCookie("test-session", "abc")
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Example - Ingress with custom skipper Predicate configuration

The example shows the use of a skipper predicates for the implicitly defined route in ingress.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/skipper-predicate: QueryParam("query", "^example$")
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Example - Ingress with custom skipper Routes configuration

The example shows the use of custom skipper routes which be additional to the routes generated for the ingress.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/skipper-routes: |
      Method("OPTIONS") ->
      setResponseHeader("Access-Control-Allow-Origin", "*") ->
      setResponseHeader("Access-Control-Allow-Methods", "GET, OPTIONS") ->
      setResponseHeader("Access-Control-Allow-Headers", "Authorization") ->
      status(200) -> <shunt>
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Example - Ingress with shadow traffic

This will send production traffic to app-default.example.org and copies incoming requests to https://app.shadow.example.org, but drops responses from shadow URL. This is helpful to test your next generation software with production workload. See also https://godoc.org/github.com/zalando/skipper/filters/tee for details.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    zalando.org/skipper-filter: tee("https://app.shadow.example.org")
  name: app
spec:
  rules:
  - host: app-default.example.org
    http:
      paths:
      - backend:
          serviceName: app-svc
          servicePort: 80

Index

• type Client
  • func New(o Options) (*Client, error)
  • func (c *Client) LoadAll() ([]*eskip.Route, error)
  • func (c *Client) LoadUpdate() ([]*eskip.Route, []string, error)
• type Options

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client is a Skipper DataClient implementation used to create routes based on Kubernetes Ingress settings.

func New

func New(o Options) (*Client, error)

New creates and initializes a Kubernetes DataClient.

func (*Client) LoadAll

func (c *Client) LoadAll() ([]*eskip.Route, error)

func (*Client) LoadUpdate

func (c *Client) LoadUpdate() ([]*eskip.Route, []string, error)

LoadUpdate returns all known eskip.Route, a list of route IDs scheduled for delete and an error.

TODO: implement a force reset after some time.

type Options

type Options struct {
	// KubernetesInCluster defines if skipper is deployed and running in the kubernetes cluster
	// this would make authentication with API server happen through the service account, rather than
	// running along side kubectl proxy
	KubernetesInCluster bool

	// KubernetesURL is used as the base URL for Kubernetes API requests. Defaults to http://localhost:8001.
	// (TBD: support in-cluster operation by taking the address and certificate from the standard Kubernetes
	// environment variables.)
	KubernetesURL string

	// ProvideHealthcheck, when set, tells the data client to append a healthcheck route to the ingress
	// routes in case of successfully receiving the ingress items from the API (even if individual ingress
	// items may be invalid), or a failing healthcheck route when the API communication fails. The
	// healthcheck endpoint can be accessed from internal IPs on any hostname, with the path
	// /kube-system/healthz.
	//
	// When used in a custom configuration, the current filter registry needs to include the status()
	// filter, and the available predicates need to include the Source() predicate.
	ProvideHealthcheck bool

	// ProvideHTTPSRedirect, when set, tells the data client to append an HTTPS redirect route to the
	// ingress routes. This route will detect the X-Forwarded-Proto=http and respond with a 301 message
	// to the HTTPS equivalent of the same request (using the redirectTo(301, "https:") filter). The
	// X-Forwarded-Proto and X-Forwarded-Port is expected to be set by the load balancer.
	//
	// (See also https://github.com/zalando-incubator/kube-ingress-aws-controller as part of the
	// https://github.com/zalando-incubator/kubernetes-on-aws project.)
	ProvideHTTPSRedirect bool

	// IngressClass is a regular expression to filter only those ingresses that match. If an ingress does
	// not have a class annotation or the annotation is an empty string, skipper will load it. The default
	// value for the ingress class is 'skipper'.
	//
	// For further information see:
	//		https://github.com/nginxinc/kubernetes-ingress/tree/master/examples/multiple-ingress-controllers
	IngressClass string

	// ReverseSourcePredicate set to true will do the Source IP
	// whitelisting for the heartbeat endpoint correctly in AWS.
	// Amazon's ALB writes the client IP to the last item of the
	// string list of the X-Forwarded-For header, in this case you
	// want to set this to true.
	ReverseSourcePredicate bool

	// Noop, WIP.
	ForceFullUpdatePeriod time.Duration
}

Options is used to initialize the Kubernetes DataClient.