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Understanding the Ingress Operator | Networking | OpenShift Container Platform 4.6
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Ingress Operator in OpenShift Container Platform

OpenShift Container Platform Ingress Operator

When you create your OpenShift Container Platform cluster, pods and services running on the cluster are each allocated their own IP addresses. The IP addresses are accessible to other pods and services running nearby but are not accessible to outside clients. The Ingress Operator implements the IngressController API and is the component responsible for enabling external access to OpenShift Container Platform cluster services.

The Ingress Operator makes it possible for external clients to access your service by deploying and managing one or more HAProxy-based Ingress Controllers to handle routing. You can use the Ingress Operator to route traffic by specifying OpenShift Container Platform Route and Kubernetes Ingress resources. Configurations within the Ingress Controller, such as the ability to define endpointPublishingStrategy type and internal load balancing, provide ways to publish Ingress Controller endpoints.

The Ingress configuration asset

The installation program generates an asset with an Ingress resource in the config.openshift.io API group, cluster-ingress-02-config.yml.

YAML Definition of the Ingress resource
apiVersion: config.openshift.io/v1
kind: Ingress
metadata:
  name: cluster
spec:
  domain: apps.openshiftdemos.com

The installation program stores this asset in the cluster-ingress-02-config.yml file in the manifests/ directory. This Ingress resource defines the cluster-wide configuration for Ingress. This Ingress configuration is used as follows:

  • The Ingress Operator uses the domain from the cluster Ingress configuration as the domain for the default Ingress Controller.

  • The OpenShift API Server Operator uses the domain from the cluster Ingress configuration. This domain is also used when generating a default host for a Route resource that does not specify an explicit host.

Ingress controller configuration parameters

The ingresscontrollers.operator.openshift.io resource offers the following configuration parameters.

Parameter Description

domain

domain is a DNS name serviced by the Ingress controller and is used to configure multiple features:

  • For the LoadBalancerService endpoint publishing strategy, domain is used to configure DNS records. See endpointPublishingStrategy.

  • When using a generated default certificate, the certificate is valid for domain and its subdomains. See defaultcertificate.

  • The value is published to individual Route statuses so that users know where to target external DNS records.

The domain value must be unique among all Ingress controllers and cannot be updated.

If empty, the default value is ingress.config.openshift.io/cluster .spec.domain.

replicas

replicas is the desired number of Ingress controller replicas. If not set, the default value is 2.

endpointPublishingStrategy

endpointPublishingStrategy is used to publish the Ingress controller endpoints to other networks, enable load balancer integrations, and provide access to other systems.

If not set, the default value is based on infrastructure.config.openshift.io/cluster .status.platform:

  • AWS: LoadBalancerService (with external scope)

  • Azure: LoadBalancerService (with external scope)

  • GCP: LoadBalancerService (with external scope)

  • Bare metal: NodePortService

  • Other: HostNetwork

The endpointPublishingStrategy value cannot be updated.

defaultcertificate

The defaultcertificate value is a reference to a secret that contains the default certificate that is served by the Ingress controller. When Routes do not specify their own certificate, defaultcertificate is used.

The secret must contain the following keys and data: * tls.crt: certificate file contents * tls.key: key file contents

If not set, a wildcard certificate is automatically generated and used. The certificate is valid for the Ingress controller domain and subdomains, and the generated certificate’s CA is automatically integrated with the cluster’s trust store.

The in-use certificate, whether generated or user-specified, is automatically integrated with OpenShift Container Platform built-in OAuth server.

namespaceSelector

namespaceSelector is used to filter the set of namespaces serviced by the Ingress controller. This is useful for implementing shards.

routeSelector

routeSelector is used to filter the set of Routes serviced by the Ingress controller. This is useful for implementing shards.

nodePlacement

nodePlacement enables explicit control over the scheduling of the Ingress controller.

If not set, the defaults values are used.

The nodePlacement parameter includes two parts, nodeSelector and tolerations. For example:

nodePlacement:
 nodeSelector:
   matchLabels:
     kubernetes.io/os: linux
 tolerations:
 - effect: NoSchedule
   operator: Exists

tlsSecurityProfile

tlsSecurityProfile specifies settings for TLS connections for Ingress controllers.

If not set, the default value is based on the apiservers.config.openshift.io/cluster resource.

When using the Old, Intermediate, and Modern profile types, the effective profile configuration is subject to change between releases. For example, given a specification to use the Intermediate profile deployed on release X.Y.Z, an upgrade to release X.Y.Z+1 may cause a new profile configuration to be applied to the Ingress controller, resulting in a rollout.

The minimum TLS version for Ingress controllers is 1.1, and the maximum TLS version is 1.2.

The HAProxy Ingress controller image does not support TLS 1.3 and because the Modern profile requires TLS 1.3, it is not supported. The Ingress Operator converts the Modern profile to Intermediate.

The Ingress Operator also converts the TLS 1.0 of an Old or Custom profile to 1.1, and TLS 1.3 of a Custom profile to 1.2.

OpenShift Container Platform router enables Red Hat-distributed OpenSSL default set of TLS 1.3 cipher suites, which uses TLS_AES_128_CCM_SHA256, TLS_CHACHA20_POLY1305_SHA256, TLS_AES_256_GCM_SHA384, and TLS_AES_128_GCM_SHA256. Your cluster might accept TLS 1.3 connections and cipher suites, even though TLS 1.3 is unsupported in OpenShift Container Platform 4.6, 4.7, and 4.8.

Ciphers and the minimum TLS version of the configured security profile are reflected in the TLSProfile status.

routeAdmission

routeAdmission defines a policy for handling new route claims, such as allowing or denying claims across namespaces.

namespaceOwnership describes how hostname claims across namespaces should be handled. The default is Strict.

  • Strict: does not allow routes to claim the same hostname across namespaces.

  • InterNamespaceAllowed: allows routes to claim different paths of the same hostname across namespaces.

wildcardPolicy describes how routes with wildcard policies are handled by the Ingress Controller.

  • WildcardsAllowed: Indicates routes with any wildcard policy are admitted by the Ingress Controller.

  • WildcardsDisallowed: Indicates only routes with a wildcard policy of None are admitted by the Ingress Controller. Updating wildcardPolicy from WildcardsAllowed to WildcardsDisallowed causes admitted routes with a wildcard policy of Subdomain to stop working. These routes must be recreated to a wildcard policy of None to be readmitted by the Ingress Controller. WildcardsDisallowed is the default setting.

IngressControllerLogging

logging defines parameters for what is logged where. If this field is empty, operational logs are enabled but access logs are disabled.

  • access describes how client requests are logged. If this field is empty, access logging is disabled.

    • destination describes a destination for log messages.

      • type is the type of destination for logs:

        • Container specifies that logs should go to a sidecar container. The Ingress Operator configures the container, named logs, on the Ingress Controller pod and configures the Ingress Controller to write logs to the container. The expectation is that the administrator configures a custom logging solution that reads logs from this container. Using container logs means that logs may be dropped if the rate of logs exceeds the container runtime capacity or the custom logging solution capacity.

        • Syslog specifies that logs are sent to a Syslog endpoint. The administrator must specify an endpoint that can receive Syslog messages. The expectation is that the administrator has configured a custom Syslog instance.

      • container describes parameters for the Container logging destination type. Currently there are no parameters for container logging, so this field must be empty.

      • syslog describes parameters for the Syslog logging destination type:

        • address is the IP address of the syslog endpoint that receives log messages.

        • port is the UDP port number of the syslog endpoint that receives log messages.

        • facility specifies the syslog facility of log messages. If this field is empty, the facility is local1. Otherwise, it must specify a valid syslog facility: kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron, auth2, ftp, ntp, audit, alert, cron2, local0, local1, local2, local3. local4, local5, local6, or local7.

    • httpLogFormat specifies the format of the log message for an HTTP request. If this field is empty, log messages use the implementation’s default HTTP log format. For HAProxy’s default HTTP log format, see the HAProxy documentation.

httpHeaders

httpHeaders defines the policy for HTTP headers.

By setting the forwardedHeaderPolicy for the IngressControllerHTTPHeaders, you specify when and how the Ingress controller sets the Forwarded, X-Forwarded-For, X-Forwarded-Host, X-Forwarded-Port, X-Forwarded-Proto, and X-Forwarded-Proto-Version HTTP headers.

By default, the policy is set to Append.

  • Append specifies that the Ingress Controller appends the headers, preserving any existing headers.

  • Replace specifies that the Ingress Controller sets the headers, removing any existing headers.

  • IfNone specifies that the Ingress Controller sets the headers if they are not already set.

  • Never specifies that the Ingress Controller never sets the headers, preserving any existing headers.

All parameters are optional.

Ingress Controller TLS security profiles

TLS security profiles provide a way for servers to regulate which ciphers a connecting client can use when connecting to the server.

Understanding TLS security profiles

You can use a TLS (Transport Layer Security) security profile to define which TLS ciphers are required by various OpenShift Container Platform components. The OpenShift Container Platform TLS security profiles are based on Mozilla recommended configurations.

You can specify one of the following TLS security profiles for each component:

Table 1. TLS security profiles
Profile Description

Old

This profile is intended for use with legacy clients or libraries. The profile is based on the Old backward compatibility recommended configuration.

The Old profile requires a minimum TLS version of 1.0.

For the Ingress Controller, the minimum TLS version is converted from 1.0 to 1.1.

Intermediate

This profile is the recommended configuration for the majority of clients. It is the default TLS security profile for the Ingress Controller and control plane. The profile is based on the Intermediate compatibility recommended configuration.

The Intermediate profile requires a minimum TLS version of 1.2.

Modern

This profile is intended for use with modern clients that have no need for backwards compatibility. This profile is based on the Modern compatibility recommended configuration.

The Modern profile requires a minimum TLS version of 1.3.

In OpenShift Container Platform 4.6, 4.7, and 4.8, the Modern profile is unsupported. If selected, the Intermediate profile is enabled.

The Modern profile is currently not supported.

Custom

This profile allows you to define the TLS version and ciphers to use.

Use caution when using a Custom profile, because invalid configurations can cause problems.

OpenShift Container Platform router enables Red Hat-distributed OpenSSL default set of TLS 1.3 cipher suites. Your cluster might accept TLS 1.3 connections and cipher suites, even though TLS 1.3 is unsupported in OpenShift Container Platform 4.6, 4.7, and 4.8.

When using one of the predefined profile types, the effective profile configuration is subject to change between releases. For example, given a specification to use the Intermediate profile deployed on release X.Y.Z, an upgrade to release X.Y.Z+1 might cause a new profile configuration to be applied, resulting in a rollout.

Configuring the TLS security profile for the Ingress Controller

To configure a TLS security profile for an Ingress Controller, edit the IngressController custom resource (CR) to specify a predefined or custom TLS security profile. If a TLS security profile is not configured, the default value is based on the TLS security profile set for the API server.

Sample IngressController CR that configures the Old TLS security profile
apiVersion: operator.openshift.io/v1
kind: IngressController
 ...
spec:
  tlsSecurityProfile:
    old: {}
    type: Old
 ...

The TLS security profile defines the minimum TLS version and the TLS ciphers for TLS connections for Ingress Controllers.

You can see the ciphers and the minimum TLS version of the configured TLS security profile in the IngressController custom resource (CR) under Status.Tls Profile and the configured TLS security profile under Spec.Tls Security Profile. For the Custom TLS security profile, the specific ciphers and minimum TLS version are listed under both parameters.

The HAProxy Ingress Controller image does not support TLS 1.3 and because the Modern profile requires TLS 1.3, it is not supported. The Ingress Operator converts the Modern profile to Intermediate. The Ingress Operator also converts the TLS 1.0 of an Old or Custom profile to 1.1, and TLS 1.3 of a Custom profile to 1.2.
Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.

Procedure

  1. Edit the IngressController CR in the openshift-ingress-operator project to configure the TLS security profile:

    $ oc edit IngressController default -n openshift-ingress-operator

  2. Add the spec.tlsSecurityProfile field:

    Sample IngressController CR for a Custom profile
    apiVersion: operator.openshift.io/v1
kind: IngressController
 ...
spec:
  tlsSecurityProfile:
    type: Custom (1)
    custom: (2)
      ciphers: (3)
      - ECDHE-ECDSA-CHACHA20-POLY1305
      - ECDHE-RSA-CHACHA20-POLY1305
      - ECDHE-RSA-AES128-GCM-SHA256
      - ECDHE-ECDSA-AES128-GCM-SHA256
      minTLSVersion: VersionTLS11
 ...
    1 Specify the TLS security profile type (Old, Intermediate, or Custom). The default is Intermediate.
    2 Specify the appropriate field for the selected type:

    • old: {}

    • intermediate: {}

    • custom:
    3 For the custom type, specify a list of TLS ciphers and minimum accepted TLS version.

  3. Save the file to apply the changes.

Verification

  • Verify that the profile is set in the IngressController CR:

    $ oc describe IngressController default -n openshift-ingress-operator
    Example output
    Name:         default
Namespace:    openshift-ingress-operator
Labels:       <none>
Annotations:  <none>
API Version:  operator.openshift.io/v1
Kind:         IngressController
 ...
Spec:
 ...
  Tls Security Profile:
    Custom:
      Ciphers:
        ECDHE-ECDSA-CHACHA20-POLY1305
        ECDHE-RSA-CHACHA20-POLY1305
        ECDHE-RSA-AES128-GCM-SHA256
        ECDHE-ECDSA-AES128-GCM-SHA256
      Min TLS Version:  VersionTLS11
    Type:               Custom
 ...

Ingress controller endpoint publishing strategy

NodePortService endpoint publishing strategy

The NodePortService endpoint publishing strategy publishes the Ingress Controller using a Kubernetes NodePort service.

In this configuration, the Ingress Controller deployment uses container networking. A NodePortService is created to publish the deployment. The specific node ports are dynamically allocated by OpenShift Container Platform; however, to support static port allocations, your changes to the node port field of the managed NodePortService are preserved.

OpenShift Container Platform Ingress NodePort endpoint publishing strategy
Figure 1. Diagram of NodePortService

The preceding graphic shows the following concepts pertaining to OpenShift Container Platform Ingress NodePort endpoint publishing strategy:

  • All the available nodes in the cluster have their own, externally accessible IP addresses. The service running in the cluster is bound to the unique NodePort for all the nodes.

  • When the client connects to a node that is down, for example, by connecting the 10.0.128.4 IP address in the graphic, the node port directly connects the client to an available node that is running the service. In this scenario, no load balancing is required. As the image shows, the 10.0.128.4 address is down and another IP address must be used instead.

The Ingress Operator ignores any updates to .spec.ports[].nodePort fields of the service.

By default, ports are allocated automatically and you can access the port allocations for integrations. However, sometimes static port allocations are necessary to integrate with existing infrastructure which may not be easily reconfigured in response to dynamic ports. To achieve integrations with static node ports, you can update the managed service resource directly.

For more information, see the Kubernetes Services documentation on NodePort.

HostNetwork endpoint publishing strategy

The HostNetwork endpoint publishing strategy publishes the Ingress Controller on node ports where the Ingress Controller is deployed.

An Ingress controller with the HostNetwork endpoint publishing strategy can have only one pod replica per node. If you want n replicas, you must use at least n nodes where those replicas can be scheduled. Because each pod replica requests ports 80 and 443 on the node host where it is scheduled, a replica cannot be scheduled to a node if another pod on the same node is using those ports.

View the default Ingress Controller

The Ingress Operator is a core feature of OpenShift Container Platform and is enabled out of the box.

Every new OpenShift Container Platform installation has an ingresscontroller named default. It can be supplemented with additional Ingress Controllers. If the default ingresscontroller is deleted, the Ingress Operator will automatically recreate it within a minute.

Procedure

  • View the default Ingress Controller:

    $ oc describe --namespace=openshift-ingress-operator ingresscontroller/default

View Ingress Operator status

You can view and inspect the status of your Ingress Operator.

Procedure

  • View your Ingress Operator status:

    $ oc describe clusteroperators/ingress

View Ingress Controller logs

You can view your Ingress Controller logs.

Procedure

  • View your Ingress Controller logs:

    $ oc logs --namespace=openshift-ingress-operator deployments/ingress-operator

View Ingress Controller status

Your can view the status of a particular Ingress Controller.

Procedure

  • View the status of an Ingress Controller:

    $ oc describe --namespace=openshift-ingress-operator ingresscontroller/<name>

Configuring the Ingress Controller

Setting a custom default certificate

As an administrator, you can configure an Ingress Controller to use a custom certificate by creating a Secret resource and editing the IngressController custom resource (CR).

Prerequisites

  • You must have a certificate/key pair in PEM-encoded files, where the certificate is signed by a trusted certificate authority or by a private trusted certificate authority that you configured in a custom PKI.

  • Your certificate meets the following requirements:

    • The certificate is valid for the ingress domain.

    • The certificate uses the subjectAltName extension to specify a wildcard domain, such as *.apps.ocp4.example.com.

  • You must have an IngressController CR. You may use the default one:

    $ oc --namespace openshift-ingress-operator get ingresscontrollers
    Example output
    NAME      AGE
default   10m

If you have intermediate certificates, they must be included in the tls.crt file of the secret containing a custom default certificate. Order matters when specifying a certificate; list your intermediate certificate(s) after any server certificate(s).
Procedure

The following assumes that the custom certificate and key pair are in the tls.crt and tls.key files in the current working directory. Substitute the actual path names for tls.crt and tls.key. You also may substitute another name for custom-certs-default when creating the Secret resource and referencing it in the IngressController CR.

This action will cause the Ingress Controller to be redeployed, using a rolling deployment strategy.

  1. Create a Secret resource containing the custom certificate in the openshift-ingress namespace using the tls.crt and tls.key files.

    $ oc --namespace openshift-ingress create secret tls custom-certs-default --cert=tls.crt --key=tls.key

  2. Update the IngressController CR to reference the new certificate secret:

    $ oc patch --type=merge --namespace openshift-ingress-operator ingresscontrollers/default \
  --patch '{"spec":{"defaultcertificate":{"name":"custom-certs-default"}}}'

  3. Verify the update was effective:

    $ echo Q |\
  openssl s_client -connect console-openshift-console.apps.<domain>:443 -showcerts 2>/dev/null |\
  openssl x509 -noout -subject -issuer -enddate

    where:

    <domain>

    Specifies the base domain name for your cluster.

    Example output
    subject=C = US, ST = NC, L = Raleigh, O = RH, OU = OCP4, CN = *.apps.example.com
issuer=C = US, ST = NC, L = Raleigh, O = RH, OU = OCP4, CN = example.com
notAfter=May 10 08:32:45 2022 GM

    The certificate secret name should match the value used to update the CR.

Once the IngressController CR has been modified, the Ingress Operator updates the Ingress Controller’s deployment to use the custom certificate.

Removing a custom default certificate

As an administrator, you can remove a custom certificate that you configured an Ingress Controller to use.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.

  • You have installed the OpenShift CLI (oc).

  • You previously configured a custom default certificate for the Ingress Controller.

Procedure

  • To remove the custom certificate and restore the certificate that ships with OpenShift Container Platform, enter the following command:

    $ oc patch -n openshift-ingress-operator ingresscontrollers/default \
  --type json -p $'- op: remove\n  path: /spec/defaultcertificate'

    There can be a delay while the cluster reconciles the new certificate configuration.

Verification

  • To confirm that the original cluster certificate is restored, enter the following command:

    $ echo Q | \
  openssl s_client -connect console-openshift-console.apps.<domain>:443 -showcerts 2>/dev/null | \
  openssl x509 -noout -subject -issuer -enddate

    where:

    <domain>

    Specifies the base domain name for your cluster.

    Example output
    subject=CN = *.apps.<domain>
issuer=CN = ingress-operator@1620633373
notAfter=May 10 10:44:36 2023 GMT

Scaling an Ingress Controller

Manually scale an Ingress Controller to meeting routing performance or availability requirements such as the requirement to increase throughput. oc commands are used to scale the IngressController resource. The following procedure provides an example for scaling up the default IngressController.

Procedure

  1. View the current number of available replicas for the default IngressController:

    $ oc get -n openshift-ingress-operator ingresscontrollers/default -o jsonpath='{$.status.availableReplicas}'
    Example output
    2

  2. Scale the default IngressController to the desired number of replicas using the oc patch command. The following example scales the default IngressController to 3 replicas:

    $ oc patch -n openshift-ingress-operator ingresscontroller/default --patch '{"spec":{"replicas": 3}}' --type=merge
    Example output
    ingresscontroller.operator.openshift.io/default patched

  3. Verify that the default IngressController scaled to the number of replicas that you specified:

    $ oc get -n openshift-ingress-operator ingresscontrollers/default -o jsonpath='{$.status.availableReplicas}'
    Example output
    3

Scaling is not an immediate action, as it takes time to create the desired number of replicas.

Configuring Ingress access logging

You can configure the Ingress Controller to enable access logs. If you have clusters that do not receive much traffic, then you can log to a sidecar. If you have high traffic clusters, to avoid exceeding the capacity of the logging stack or to integrate with a logging infrastructure outside of OpenShift Container Platform, you can forward logs to a custom syslog endpoint. You can also specify the format for access logs.

Container logging is useful to enable access logs on low-traffic clusters when there is no existing Syslog logging infrastructure, or for short-term use while diagnosing problems with the Ingress Controller.

Syslog is needed for high-traffic clusters where access logs could exceed the cluster logging stack’s capacity, or for environments where any logging solution needs to integrate with an existing Syslog logging infrastructure. The Syslog use-cases can overlap.

Prerequisites

  • Log in as a user with cluster-admin privileges.

Procedure

Configure Ingress access logging to a sidecar.

  • To configure Ingress access logging, you must specify a destination using spec.logging.access.destination. To specify logging to a sidecar container, you must specify Container spec.logging.access.destination.type. The following example is an Ingress Controller definition that logs to a Container destination:

    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: default
  namespace: openshift-ingress-operator
spec:
  replicas: 2
  endpointPublishingStrategy:
    type: NodePortService (1)
  logging:
    access:
      destination:
        type: Container
    1 NodePortService is not required to configure Ingress access logging to a sidecar. Ingress logging is compatible with any endpointPublishingStrategy.

  • When you configure the Ingress Controller to log to a sidecar, the operator creates a container named logs inside the Ingress Controller Pod:

    $ oc -n openshift-ingress logs deployment.apps/router-default -c logs
    Example output
    2020-05-11T19:11:50.135710+00:00 router-default-57dfc6cd95-bpmk6 router-default-57dfc6cd95-bpmk6 haproxy[108]: 174.19.21.82:39654 [11/May/2020:19:11:50.133] public be_http:hello-openshift:hello-openshift/pod:hello-openshift:hello-openshift:10.128.2.12:8080 0/0/1/0/1 200 142 - - --NI 1/1/0/0/0 0/0 "GET / HTTP/1.1"

Configure Ingress access logging to a Syslog endpoint.

  • To configure Ingress access logging, you must specify a destination using spec.logging.access.destination. To specify logging to a Syslog endpoint destination, you must specify Syslog for spec.logging.access.destination.type. If the destination type is Syslog, you must also specify a destination endpoint using spec.logging.access.destination.syslog.endpoint and you can specify a facility using spec.logging.access.destination.syslog.facility. The following example is an Ingress Controller definition that logs to a Syslog destination:

    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: default
  namespace: openshift-ingress-operator
spec:
  replicas: 2
  endpointPublishingStrategy:
    type: NodePortService
  logging:
    access:
      destination:
        type: Syslog
        syslog:
          address: 1.2.3.4
          port: 10514

    The syslog destination port must be UDP.

Configure Ingress access logging with a specific log format.

  • You can specify spec.logging.access.httpLogFormat to customize the log format. The following example is an Ingress Controller definition that logs to a syslog endpoint with IP address 1.2.3.4 and port 10514:

    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: default
  namespace: openshift-ingress-operator
spec:
  replicas: 2
  endpointPublishingStrategy:
    type: NodePortService
  logging:
    access:
      destination:
        type: Syslog
        syslog:
          address: 1.2.3.4
          port: 10514
      httpLogFormat: '%ci:%cp [%t] %ft %b/%s %B %bq %HM %HU %HV'

Disable Ingress access logging.

  • To disable Ingress access logging, leave spec.logging or spec.logging.access empty:

    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: default
  namespace: openshift-ingress-operator
spec:
  replicas: 2
  endpointPublishingStrategy:
    type: NodePortService
  logging:
    access: null

Ingress Controller sharding

As the primary mechanism for traffic to enter the cluster, the demands on the Ingress Controller, or router, can be significant. As a cluster administrator, you can shard the routes to:

  • Balance Ingress Controllers, or routers, with several routes to speed up responses to changes.

  • Allocate certain routes to have different reliability guarantees than other routes.

  • Allow certain Ingress Controllers to have different policies defined.

  • Allow only specific routes to use additional features.

  • Expose different routes on different addresses so that internal and external users can see different routes, for example.

Ingress Controller can use either route labels or namespace labels as a sharding method.

Configuring Ingress Controller sharding by using route labels

Ingress Controller sharding by using route labels means that the Ingress Controller serves any route in any namespace that is selected by the route selector.

Ingress Controller sharding is useful when balancing incoming traffic load among a set of Ingress Controllers and when isolating traffic to a specific Ingress Controller. For example, company A goes to one Ingress Controller and company B to another.

Procedure

  1. Edit the router-internal.yaml file:

    # cat router-internal.yaml
apiVersion: v1
items:
- apiVersion: operator.openshift.io/v1
  kind: IngressController
  metadata:
    name: sharded
    namespace: openshift-ingress-operator
  spec:
    domain: <apps-sharded.basedomain.example.net>
    nodePlacement:
      nodeSelector:
        matchLabels:
          node-role.kubernetes.io/worker: ""
    routeSelector:
      matchLabels:
        type: sharded
  status: {}
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""

  2. Apply the Ingress Controller router-internal.yaml file:

    # oc apply -f router-internal.yaml

    The Ingress Controller selects routes in any namespace that have the label type: sharded.

Configuring Ingress Controller sharding by using namespace labels

Ingress Controller sharding by using namespace labels means that the Ingress Controller serves any route in any namespace that is selected by the namespace selector.

Ingress Controller sharding is useful when balancing incoming traffic load among a set of Ingress Controllers and when isolating traffic to a specific Ingress Controller. For example, company A goes to one Ingress Controller and company B to another.

If you deploy the Keepalived Ingress VIP, do not deploy a non-default Ingress Controller with value HostNetwork for the endpointPublishingStrategy parameter. Doing so might cause issues. Use value NodePort instead of HostNetwork for endpointPublishingStrategy.
Procedure

  1. Edit the router-internal.yaml file:

    # cat router-internal.yaml
    Example output
    apiVersion: v1
items:
- apiVersion: operator.openshift.io/v1
  kind: IngressController
  metadata:
    name: sharded
    namespace: openshift-ingress-operator
  spec:
    domain: <apps-sharded.basedomain.example.net>
    nodePlacement:
      nodeSelector:
        matchLabels:
          node-role.kubernetes.io/worker: ""
    namespaceSelector:
      matchLabels:
        type: sharded
  status: {}
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""

  2. Apply the Ingress Controller router-internal.yaml file:

    # oc apply -f router-internal.yaml

    The Ingress Controller selects routes in any namespace that is selected by the namespace selector that have the label type: sharded.

Configuring an Ingress Controller to use an internal load balancer

When creating an Ingress Controller on cloud platforms, the Ingress Controller is published by a public cloud load balancer by default. As an administrator, you can create an Ingress Controller that uses an internal cloud load balancer.

If your cloud provider is Microsoft Azure, you must have at least one public load balancer that points to your nodes. If you do not, all of your nodes will lose egress connectivity to the internet.

If you want to change the scope for an IngressController object, you must delete and then recreate that IngressController object. You cannot change the .spec.endpointPublishingStrategy.loadBalancer.scope parameter after the custom resource (CR) is created.
OpenShift Container Platform Ingress LoadBalancerService endpoint publishing strategy
Figure 2. Diagram of LoadBalancer

The preceding graphic shows the following concepts pertaining to OpenShift Container Platform Ingress LoadBalancerService endpoint publishing strategy:

  • You can load load balance externally, using the cloud provider load balancer, or internally, using the OpenShift Ingress Controller Load Balancer.

  • You can use the single IP address of the load balancer and more familiar ports, such as 8080 and 4200 as shown on the cluster depicted in the graphic.

  • Traffic from the external load balancer is directed at the pods, and managed by the load balancer, as depicted in the instance of a down node. See the Kubernetes Services documentation for implementation details.

Prerequisites

  • Install the OpenShift CLI (oc).

  • Log in as a user with cluster-admin privileges.

Procedure

  1. Create an IngressController custom resource (CR) in a file named <name>-ingress-controller.yaml, such as in the following example:

    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  namespace: openshift-ingress-operator
  name: <name> (1)
spec:
  domain: <domain> (2)
  endpointPublishingStrategy:
    type: LoadBalancerService
    loadBalancer:
      scope: Internal (3)
    1 Replace <name> with a name for the IngressController object.
    2 Specify the domain for the application published by the controller.
    3 Specify a value of Internal to use an internal load balancer.

  2. Create the Ingress Controller defined in the previous step by running the following command:

    $ oc create -f <name>-ingress-controller.yaml (1)
    1 Replace <name> with the name of the IngressController object.

  3. Optional: Confirm that the Ingress Controller was created by running the following command:

    $ oc --all-namespaces=true get ingresscontrollers

Configuring the default Ingress Controller for your cluster to be internal

You can configure the default Ingress Controller for your cluster to be internal by deleting and recreating it.

If your cloud provider is Microsoft Azure, you must have at least one public load balancer that points to your nodes. If you do not, all of your nodes will lose egress connectivity to the internet.

If you want to change the scope for an IngressController object, you must delete and then recreate that IngressController object. You cannot change the .spec.endpointPublishingStrategy.loadBalancer.scope parameter after the custom resource (CR) is created.
Prerequisites

  • Install the OpenShift CLI (oc).

  • Log in as a user with cluster-admin privileges.

Procedure

  1. Configure the default Ingress Controller for your cluster to be internal by deleting and recreating it.

    $ oc replace --force --wait --filename - <<EOF
apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  namespace: openshift-ingress-operator
  name: default
spec:
  endpointPublishingStrategy:
    type: LoadBalancerService
    loadBalancer:
      scope: Internal
EOF

Configuring the route admission policy

Administrators and application developers can run applications in multiple namespaces with the same domain name. This is for organizations where multiple teams develop microservices that are exposed on the same hostname.

Allowing claims across namespaces should only be enabled for clusters with trust between namespaces, otherwise a malicious user could take over a hostname. For this reason, the default admission policy disallows hostname claims across namespaces.
Prerequisites

  • Cluster administrator privileges.

Procedure

  • Edit the .spec.routeAdmission field of the ingresscontroller resource variable using the following command:

    $ oc -n openshift-ingress-operator patch ingresscontroller/default --patch '{"spec":{"routeAdmission":{"namespaceOwnership":"InterNamespaceAllowed"}}}' --type=merge
    Sample Ingress Controller configuration
    spec:
  routeAdmission:
    namespaceOwnership: InterNamespaceAllowed
...

Using wildcard routes

The HAProxy Ingress Controller has support for wildcard routes. The Ingress Operator uses wildcardPolicy to configure the ROUTER_ALLOW_WILDCARD_ROUTES environment variable of the Ingress Controller.

The default behavior of the Ingress Controller is to admit routes with a wildcard policy of None, which is backwards compatible with existing IngressController resources.

Procedure

  1. Configure the wildcard policy.

    1. Use the following command to edit the IngressController resource:

      $ oc edit IngressController

    2. Under spec, set the wildcardPolicy field to WildcardsDisallowed or WildcardsAllowed:

      spec:
  routeAdmission:
    wildcardPolicy: WildcardsDisallowed # or WildcardsAllowed

Using X-Forwarded headers

You configure the HAProxy Ingress Controller to specify a policy for how to handle HTTP headers including Forwarded and X-Forwarded-For. The Ingress Operator uses the HTTPHeaders field to configure the ROUTER_SET_FORWARDED_HEADERS environment variable of the Ingress Controller.

Procedure

  1. Configure the HTTPHeaders field for the Ingress Controller.

    1. Use the following command to edit the IngressController resource:

      $ oc edit IngressController

    2. Under spec, set the HTTPHeaders policy field to Append, Replace, IfNone, or Never:

      apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: default
  namespace: openshift-ingress-operator
spec:
  httpHeaders:
    forwardedHeaderPolicy: Append

Example use cases

As a cluster administrator, you can:

  • Configure an external proxy that injects the X-Forwarded-For header into each request before forwarding it to an Ingress Controller.

    To configure the Ingress Controller to pass the header through unmodified, you specify the never policy. The Ingress Controller then never sets the headers, and applications receive only the headers that the external proxy provides.

  • Configure the Ingress Controller to pass the X-Forwarded-For header that your external proxy sets on external cluster requests through unmodified.

    To configure the Ingress Controller to set the X-Forwarded-For header on internal cluster requests, which do not go through the external proxy, specify the if-none policy. If an HTTP request already has the header set through the external proxy, then the Ingress Controller preserves it. If the header is absent because the request did not come through the proxy, then the Ingress Controller adds the header.

As an application developer, you can:

  • Configure an application-specific external proxy that injects the X-Forwarded-For header.

    To configure an Ingress Controller to pass the header through unmodified for an application’s Route, without affecting the policy for other Routes, add an annotation haproxy.router.openshift.io/set-forwarded-headers: if-none or haproxy.router.openshift.io/set-forwarded-headers: never on the Route for the application.

    You can set the haproxy.router.openshift.io/set-forwarded-headers annotation on a per route basis, independent from the globally set value for the Ingress Controller.

Enabling HTTP/2 Ingress connectivity

You can enable transparent end-to-end HTTP/2 connectivity in HAProxy. It allows application owners to make use of HTTP/2 protocol capabilities, including single connection, header compression, binary streams, and more.

You can enable HTTP/2 connectivity for an individual Ingress Controller or for the entire cluster.

To enable the use of HTTP/2 for the connection from the client to HAProxy, a route must specify a custom certificate. A route that uses the default certificate cannot use HTTP/2. This restriction is necessary to avoid problems from connection coalescing, where the client re-uses a connection for different routes that use the same certificate.

The connection from HAProxy to the application pod can use HTTP/2 only for re-encrypt routes and not for edge-terminated or insecure routes. This restriction is because HAProxy uses Application-Level Protocol Negotiation (ALPN), which is a TLS extension, to negotiate the use of HTTP/2 with the back-end. The implication is that end-to-end HTTP/2 is possible with passthrough and re-encrypt and not with insecure or edge-terminated routes.

Using WebSockets with a re-encrypt route and with HTTP/2 enabled on an Ingress Controller requires WebSocket support over HTTP/2. WebSockets over HTTP/2 is a feature of HAProxy 2.4, which is unsupported in OpenShift Container Platform at this time.

For non-passthrough routes, the Ingress Controller negotiates its connection to the application independently of the connection from the client. This means a client may connect to the Ingress Controller and negotiate HTTP/1.1, and the Ingress Controller may then connect to the application, negotiate HTTP/2, and forward the request from the client HTTP/1.1 connection using the HTTP/2 connection to the application. This poses a problem if the client subsequently tries to upgrade its connection from HTTP/1.1 to the WebSocket protocol, because the Ingress Controller cannot forward WebSocket to HTTP/2 and cannot upgrade its HTTP/2 connection to WebSocket. Consequently, if you have an application that is intended to accept WebSocket connections, it must not allow negotiating the HTTP/2 protocol or else clients will fail to upgrade to the WebSocket protocol.
Procedure

Enable HTTP/2 on a single Ingress Controller.

  • To enable HTTP/2 on an Ingress Controller, enter the oc annotate command:

    $ oc -n openshift-ingress-operator annotate ingresscontrollers/<ingresscontroller_name> ingress.operator.openshift.io/default-enable-http2=true

    Replace <ingresscontroller_name> with the name of the Ingress Controller to annotate.

Enable HTTP/2 on the entire cluster.

  • To enable HTTP/2 for the entire cluster, enter the oc annotate command:

    $ oc annotate ingresses.config/cluster ingress.operator.openshift.io/default-enable-http2=true

Additional resources