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Limitations of load balancer services

OKD clusters on OpenStack use Octavia to handle load balancer services. As a result of this choice, such clusters have a number of functional limitations.

OpenStack Octavia has two supported providers: Amphora and OVN. These providers differ in terms of available features as well as implementation details. These distinctions affect load balancer services that are created on your cluster.

Local external traffic policies

You can set the external traffic policy (ETP) parameter, .spec.externalTrafficPolicy, on a load balancer service to preserve the source IP address of incoming traffic when it reaches service endpoint pods. However, if your cluster uses the Amphora Octavia provider, the source IP of the traffic is replaced with the IP address of the Amphora VM. This behavior does not occur if your cluster uses the OVN Octavia provider.

Having the ETP option set to Local requires that health monitors be created for the load balancer. Without health monitors, traffic can be routed to a node that doesn’t have a functional endpoint, which causes the connection to drop. To force Cloud Provider OpenStack to create health monitors, you must set the value of the create-monitor option in the cloud provider configuration to true.

In OpenStack 16.2, the OVN Octavia provider does not support health monitors. Therefore, setting the ETP to local is unsupported.

In OpenStack 16.2, the Amphora Octavia provider does not support HTTP monitors on UDP pools. As a result, UDP load balancer services have UDP-CONNECT monitors created instead. Due to implementation details, this configuration only functions properly with the OVN-Kubernetes CNI plugin. When the OpenShift SDN CNI plugin is used, the UDP services alive nodes are detected unreliably.

Load balancer source ranges

Use the .spec.loadBalancerSourceRanges property to restrict the traffic that can pass through the load balancer according to source IP. This property is supported for use with the Amphora Octavia provider only. If your cluster uses the OVN Octavia provider, the option is ignored and traffic is unrestricted.

Using the Octavia OVN load balancer provider driver with Kuryr SDN

Kuryr is a deprecated feature. Deprecated functionality is still included in OKD and continues to be supported; however, it will be removed in a future release of this product and is not recommended for new deployments.

For the most recent list of major functionality that has been deprecated or removed within OKD, refer to the Deprecated and removed features section of the OKD release notes.

If your OKD cluster uses Kuryr and was installed on a OpenStack 13 cloud that was later upgraded to OpenStack 16, you can configure it to use the Octavia OVN provider driver.

Kuryr replaces existing load balancers after you change provider drivers. This process results in some downtime.

Prerequisites
  • Install the OpenStack CLI, openstack.

  • Install the OKD CLI, oc.

  • Verify that the Octavia OVN driver on OpenStack is enabled.

    To view a list of available Octavia drivers, on a command line, enter openstack loadbalancer provider list.

    The ovn driver is displayed in the command’s output.

Procedure

To change from the Octavia Amphora provider driver to Octavia OVN:

  1. Open the kuryr-config ConfigMap. On a command line, enter:

    $ oc -n openshift-kuryr edit cm kuryr-config
  2. In the ConfigMap, delete the line that contains kuryr-octavia-provider: default. For example:

    ...
    kind: ConfigMap
    metadata:
      annotations:
        networkoperator.openshift.io/kuryr-octavia-provider: default (1)
    ...
    1 Delete this line. The cluster will regenerate it with ovn as the value.

    Wait for the Cluster Network Operator to detect the modification and to redeploy the kuryr-controller and kuryr-cni pods. This process might take several minutes.

  3. Verify that the kuryr-config ConfigMap annotation is present with ovn as its value. On a command line, enter:

    $ oc -n openshift-kuryr edit cm kuryr-config

    The ovn provider value is displayed in the output:

    ...
    kind: ConfigMap
    metadata:
      annotations:
        networkoperator.openshift.io/kuryr-octavia-provider: ovn
    ...
  4. Verify that OpenStack recreated its load balancers.

    1. On a command line, enter:

      $ openstack loadbalancer list | grep amphora

      A single Amphora load balancer is displayed. For example:

      a4db683b-2b7b-4988-a582-c39daaad7981 | ostest-7mbj6-kuryr-api-loadbalancer  | 84c99c906edd475ba19478a9a6690efd | 172.30.0.1     | ACTIVE              | amphora
    2. Search for ovn load balancers by entering:

      $ openstack loadbalancer list | grep ovn

      The remaining load balancers of the ovn type are displayed. For example:

      2dffe783-98ae-4048-98d0-32aa684664cc | openshift-apiserver-operator/metrics | 84c99c906edd475ba19478a9a6690efd | 172.30.167.119 | ACTIVE              | ovn
      0b1b2193-251f-4243-af39-2f99b29d18c5 | openshift-etcd/etcd                  | 84c99c906edd475ba19478a9a6690efd | 172.30.143.226 | ACTIVE              | ovn
      f05b07fc-01b7-4673-bd4d-adaa4391458e | openshift-dns-operator/metrics       | 84c99c906edd475ba19478a9a6690efd | 172.30.152.27  | ACTIVE              | ovn

Scaling clusters for application traffic by using Octavia

OKD clusters that run on OpenStack can use the Octavia load balancing service to distribute traffic across multiple virtual machines (VMs) or floating IP addresses. This feature mitigates the bottleneck that single machines or addresses create.

If your cluster uses Kuryr, the Cluster Network Operator created an internal Octavia load balancer at deployment. You can use this load balancer for application network scaling.

If your cluster does not use Kuryr, you must create your own Octavia load balancer to use it for application network scaling.

Scaling clusters by using Octavia

If you want to use multiple API load balancers, or if your cluster does not use Kuryr, create an Octavia load balancer and then configure your cluster to use it.

Prerequisites
  • Octavia is available on your OpenStack deployment.

Procedure
  1. From a command line, create an Octavia load balancer that uses the Amphora driver:

    $ openstack loadbalancer create --name API_OCP_CLUSTER --vip-subnet-id <id_of_worker_vms_subnet>

    You can use a name of your choice instead of API_OCP_CLUSTER.

  2. After the load balancer becomes active, create listeners:

    $ openstack loadbalancer listener create --name API_OCP_CLUSTER_6443 --protocol HTTPS--protocol-port 6443 API_OCP_CLUSTER

    To view the status of the load balancer, enter openstack loadbalancer list.

  3. Create a pool that uses the round robin algorithm and has session persistence enabled:

    $ openstack loadbalancer pool create --name API_OCP_CLUSTER_pool_6443 --lb-algorithm ROUND_ROBIN --session-persistence type=<source_IP_address> --listener API_OCP_CLUSTER_6443 --protocol HTTPS
  4. To ensure that control plane machines are available, create a health monitor:

    $ openstack loadbalancer healthmonitor create --delay 5 --max-retries 4 --timeout 10 --type TCP API_OCP_CLUSTER_pool_6443
  5. Add the control plane machines as members of the load balancer pool:

    $ for SERVER in $(MASTER-0-IP MASTER-1-IP MASTER-2-IP)
    do
      openstack loadbalancer member create --address $SERVER  --protocol-port 6443 API_OCP_CLUSTER_pool_6443
    done
  6. Optional: To reuse the cluster API floating IP address, unset it:

    $ openstack floating ip unset $API_FIP
  7. Add either the unset API_FIP or a new address to the created load balancer VIP:

    $ openstack floating ip set  --port $(openstack loadbalancer show -c <vip_port_id> -f value API_OCP_CLUSTER) $API_FIP

Your cluster now uses Octavia for load balancing.

If Kuryr uses the Octavia Amphora driver, all traffic is routed through a single Amphora virtual machine (VM).

You can repeat this procedure to create additional load balancers, which can alleviate the bottleneck.

Scaling clusters that use Kuryr by using Octavia

Kuryr is a deprecated feature. Deprecated functionality is still included in OKD and continues to be supported; however, it will be removed in a future release of this product and is not recommended for new deployments.

For the most recent list of major functionality that has been deprecated or removed within OKD, refer to the Deprecated and removed features section of the OKD release notes.

If your cluster uses Kuryr, associate the API floating IP address of your cluster with the pre-existing Octavia load balancer.

Prerequisites
  • Your OKD cluster uses Kuryr.

  • Octavia is available on your OpenStack deployment.

Procedure
  1. Optional: From a command line, to reuse the cluster API floating IP address, unset it:

    $ openstack floating ip unset $API_FIP
  2. Add either the unset API_FIP or a new address to the created load balancer VIP:

    $ openstack floating ip set --port $(openstack loadbalancer show -c <vip_port_id> -f value ${OCP_CLUSTER}-kuryr-api-loadbalancer) $API_FIP

Your cluster now uses Octavia for load balancing.

If Kuryr uses the Octavia Amphora driver, all traffic is routed through a single Amphora virtual machine (VM).

You can repeat this procedure to create additional load balancers, which can alleviate the bottleneck.

Scaling for ingress traffic by using OpenStack Octavia

Kuryr is a deprecated feature. Deprecated functionality is still included in OKD and continues to be supported; however, it will be removed in a future release of this product and is not recommended for new deployments.

For the most recent list of major functionality that has been deprecated or removed within OKD, refer to the Deprecated and removed features section of the OKD release notes.

You can use Octavia load balancers to scale Ingress controllers on clusters that use Kuryr.

Prerequisites
  • Your OKD cluster uses Kuryr.

  • Octavia is available on your OpenStack deployment.

Procedure
  1. To copy the current internal router service, on a command line, enter:

    $ oc -n openshift-ingress get svc router-internal-default -o yaml > external_router.yaml
  2. In the file external_router.yaml, change the values of metadata.name and spec.type to LoadBalancer.

    Example router file
    apiVersion: v1
    kind: Service
    metadata:
      labels:
        ingresscontroller.operator.openshift.io/owning-ingresscontroller: default
      name: router-external-default (1)
      namespace: openshift-ingress
    spec:
      ports:
      - name: http
        port: 80
        protocol: TCP
        targetPort: http
      - name: https
        port: 443
        protocol: TCP
        targetPort: https
      - name: metrics
        port: 1936
        protocol: TCP
        targetPort: 1936
      selector:
        ingresscontroller.operator.openshift.io/deployment-ingresscontroller: default
      sessionAffinity: None
      type: LoadBalancer (2)
    1 Ensure that this value is descriptive, like router-external-default.
    2 Ensure that this value is LoadBalancer.

You can delete timestamps and other information that is irrelevant to load balancing.

  1. From a command line, create a service from the external_router.yaml file:

    $ oc apply -f external_router.yaml
  2. Verify that the external IP address of the service is the same as the one that is associated with the load balancer:

    1. On a command line, retrieve the external IP address of the service:

      $ oc -n openshift-ingress get svc
      Example output
      NAME                      TYPE           CLUSTER-IP       EXTERNAL-IP    PORT(S)                                     AGE
      router-external-default   LoadBalancer   172.30.235.33    10.46.22.161   80:30112/TCP,443:32359/TCP,1936:30317/TCP   3m38s
      router-internal-default   ClusterIP      172.30.115.123   <none>         80/TCP,443/TCP,1936/TCP                     22h
    2. Retrieve the IP address of the load balancer:

      $ openstack loadbalancer list | grep router-external
      Example output
      | 21bf6afe-b498-4a16-a958-3229e83c002c | openshift-ingress/router-external-default | 66f3816acf1b431691b8d132cc9d793c | 172.30.235.33  | ACTIVE | octavia |
    3. Verify that the addresses you retrieved in the previous steps are associated with each other in the floating IP list:

      $ openstack floating ip list | grep 172.30.235.33
      Example output
      | e2f80e97-8266-4b69-8636-e58bacf1879e | 10.46.22.161 | 172.30.235.33 | 655e7122-806a-4e0a-a104-220c6e17bda6 | a565e55a-99e7-4d15-b4df-f9d7ee8c9deb | 66f3816acf1b431691b8d132cc9d793c |

You can now use the value of EXTERNAL-IP as the new Ingress address.

If Kuryr uses the Octavia Amphora driver, all traffic is routed through a single Amphora virtual machine (VM).

You can repeat this procedure to create additional load balancers, which can alleviate the bottleneck.

Configuring an external load balancer

You can configure an OKD cluster on OpenStack to use an external load balancer in place of the default load balancer.

Configuring an external load balancer depends on your vendor’s load balancer.

The information and examples in this section are for guideline purposes only. Consult the vendor documentation for more specific information about the vendor’s load balancer.

Red Hat supports the following services for an external load balancer:

  • Ingress Controller

  • OpenShift API

  • OpenShift MachineConfig API

You can choose whether you want to configure one or all of these services for an external load balancer. Configuring only the Ingress Controller service is a common configuration option. To better understand each service, view the following diagrams:

An image that shows an example network workflow of an Ingress Controller operating in an OKD environment.
Figure 1. Example network workflow that shows an Ingress Controller operating in an OKD environment
An image that shows an example network workflow of an OpenShift API operating in an OKD environment.
Figure 2. Example network workflow that shows an OpenShift API operating in an OKD environment
An image that shows an example network workflow of an OpenShift MachineConfig API operating in an OKD environment.
Figure 3. Example network workflow that shows an OpenShift MachineConfig API operating in an OKD environment
Considerations
  • For a front-end IP address, you can use the same IP address for the front-end IP address, the Ingress Controller’s load balancer, and API load balancer. Check the vendor’s documentation for this capability.

  • For a back-end IP address, ensure that an IP address for an OKD control plane node does not change during the lifetime of the external load balancer. You can achieve this by completing one of the following actions:

    • Assign a static IP address to each control plane node.

    • Configure each node to receive the same IP address from the DHCP every time the node requests a DHCP lease. Depending on the vendor, the DHCP lease might be in the form of an IP reservation or a static DHCP assignment.

  • Manually define each node that runs the Ingress Controller in the external load balancer for the Ingress Controller back-end service. For example, if the Ingress Controller moves to an undefined node, a connection outage can occur.

OpenShift API prerequisites
  • You defined a front-end IP address.

  • TCP ports 6443 and 22623 are exposed on the front-end IP address of your load balancer. Check the following items:

    • Port 6443 provides access to the OpenShift API service.

    • Port 22623 can provide ignition startup configurations to nodes.

  • The front-end IP address and port 6443 are reachable by all users of your system with a location external to your OKD cluster.

  • The front-end IP address and port 22623 are reachable only by OKD nodes.

  • The load balancer backend can communicate with OKD control plane nodes on port 6443 and 22623.

Ingress Controller prerequisites
  • You defined a front-end IP address.

  • TCP ports 443 and 80 are exposed on the front-end IP address of your load balancer.

  • The front-end IP address, port 80 and port 443 are be reachable by all users of your system with a location external to your OKD cluster.

  • The front-end IP address, port 80 and port 443 are reachable to all nodes that operate in your OKD cluster.

  • The load balancer backend can communicate with OKD nodes that run the Ingress Controller on ports 80, 443, and 1936.

Prerequisite for health check URL specifications

You can configure most load balancers by setting health check URLs that determine if a service is available or unavailable. OKD provides these health checks for the OpenShift API, Machine Configuration API, and Ingress Controller backend services.

The following examples demonstrate health check specifications for the previously listed backend services:

Example of a Kubernetes API health check specification
Path: HTTPS:6443/readyz
Healthy threshold: 2
Unhealthy threshold: 2
Timeout: 10
Interval: 10
Example of a Machine Config API health check specification
Path: HTTPS:22623/healthz
Healthy threshold: 2
Unhealthy threshold: 2
Timeout: 10
Interval: 10
Example of an Ingress Controller health check specification
Path: HTTP:1936/healthz/ready
Healthy threshold: 2
Unhealthy threshold: 2
Timeout: 5
Interval: 10
Procedure
  1. Configure the HAProxy Ingress Controller, so that you can enable access to the cluster from your load balancer on ports 6443, 443, and 80:

    Example HAProxy configuration
    #...
    listen my-cluster-api-6443
        bind 192.168.1.100:6443
        mode tcp
        balance roundrobin
      option httpchk
      http-check connect
      http-check send meth GET uri /readyz
      http-check expect status 200
        server my-cluster-master-2 192.168.1.101:6443 check inter 10s rise 2 fall 2
        server my-cluster-master-0 192.168.1.102:6443 check inter 10s rise 2 fall 2
        server my-cluster-master-1 192.168.1.103:6443 check inter 10s rise 2 fall 2
    
    listen my-cluster-machine-config-api-22623
        bind 192.168.1.1000.0.0.0:22623
        mode tcp
        balance roundrobin
      option httpchk
      http-check connect
      http-check send meth GET uri /healthz
      http-check expect status 200
        server my-cluster-master-2 192.0168.21.2101:22623 check inter 10s rise 2 fall 2
        server my-cluster-master-0 192.168.1.1020.2.3:22623 check inter 10s rise 2 fall 2
        server my-cluster-master-1 192.168.1.1030.2.1:22623 check inter 10s rise 2 fall 2
    
    listen my-cluster-apps-443
            bind 192.168.1.100:443
            mode tcp
            balance roundrobin
        option httpchk
        http-check connect
        http-check send meth GET uri /healthz/ready
        http-check expect status 200
            server my-cluster-worker-0 192.168.1.111:443 check port 1936 inter 10s rise 2 fall 2
            server my-cluster-worker-1 192.168.1.112:443 check port 1936 inter 10s rise 2 fall 2
            server my-cluster-worker-2 192.168.1.113:443 check port 1936 inter 10s rise 2 fall 2
    
    listen my-cluster-apps-80
            bind 192.168.1.100:80
            mode tcp
            balance roundrobin
        option httpchk
        http-check connect
        http-check send meth GET uri /healthz/ready
        http-check expect status 200
            server my-cluster-worker-0 192.168.1.111:80 check port 1936 inter 10s rise 2 fall 2
            server my-cluster-worker-1 192.168.1.112:80 check port 1936 inter 10s rise 2 fall 2
            server my-cluster-worker-2 192.168.1.113:80 check port 1936 inter 10s rise 2 fall 2
    # ...
  2. Use the curl CLI command to verify that the external load balancer and its resources are operational:

    1. Verify that the cluster machine configuration API is accessible to the Kubernetes API server resource, by running the following command and observing the response:

      $ curl https://<loadbalancer_ip_address>:6443/version --insecure

      If the configuration is correct, you receive a JSON object in response:

      {
        "major": "1",
        "minor": "11+",
        "gitVersion": "v1.11.0+ad103ed",
        "gitCommit": "ad103ed",
        "gitTreeState": "clean",
        "buildDate": "2019-01-09T06:44:10Z",
        "goVersion": "go1.10.3",
        "compiler": "gc",
        "platform": "linux/amd64"
      }
    2. Verify that the cluster machine configuration API is accessible to the Machine config server resource, by running the following command and observing the output:

      $ curl -v https://<loadbalancer_ip_address>:22623/healthz --insecure

      If the configuration is correct, the output from the command shows the following response:

      HTTP/1.1 200 OK
      Content-Length: 0
    3. Verify that the controller is accessible to the Ingress Controller resource on port 80, by running the following command and observing the output:

      $ curl -I -L -H "Host: console-openshift-console.apps.<cluster_name>.<base_domain>" http://<load_balancer_front_end_IP_address>

      If the configuration is correct, the output from the command shows the following response:

      HTTP/1.1 302 Found
      content-length: 0
      location: https://console-openshift-console.apps.ocp4.private.opequon.net/
      cache-control: no-cache
    4. Verify that the controller is accessible to the Ingress Controller resource on port 443, by running the following command and observing the output:

      $ curl -I -L --insecure --resolve console-openshift-console.apps.<cluster_name>.<base_domain>:443:<Load Balancer Front End IP Address> https://console-openshift-console.apps.<cluster_name>.<base_domain>

      If the configuration is correct, the output from the command shows the following response:

      HTTP/1.1 200 OK
      referrer-policy: strict-origin-when-cross-origin
      set-cookie: csrf-token=UlYWOyQ62LWjw2h003xtYSKlh1a0Py2hhctw0WmV2YEdhJjFyQwWcGBsja261dGLgaYO0nxzVErhiXt6QepA7g==; Path=/; Secure; SameSite=Lax
      x-content-type-options: nosniff
      x-dns-prefetch-control: off
      x-frame-options: DENY
      x-xss-protection: 1; mode=block
      date: Wed, 04 Oct 2023 16:29:38 GMT
      content-type: text/html; charset=utf-8
      set-cookie: 1e2670d92730b515ce3a1bb65da45062=1bf5e9573c9a2760c964ed1659cc1673; path=/; HttpOnly; Secure; SameSite=None
      cache-control: private
  3. Configure the DNS records for your cluster to target the front-end IP addresses of the external load balancer. You must update records to your DNS server for the cluster API and applications over the load balancer.

    Examples of modified DNS records
    <load_balancer_ip_address>  A  api.<cluster_name>.<base_domain>
    A record pointing to Load Balancer Front End
    <load_balancer_ip_address>   A apps.<cluster_name>.<base_domain>
    A record pointing to Load Balancer Front End

    DNS propagation might take some time for each DNS record to become available. Ensure that each DNS record propagates before validating each record.

  4. Use the curl CLI command to verify that the external load balancer and DNS record configuration are operational:

    1. Verify that you can access the cluster API, by running the following command and observing the output:

      $ curl https://api.<cluster_name>.<base_domain>:6443/version --insecure

      If the configuration is correct, you receive a JSON object in response:

      {
        "major": "1",
        "minor": "11+",
        "gitVersion": "v1.11.0+ad103ed",
        "gitCommit": "ad103ed",
        "gitTreeState": "clean",
        "buildDate": "2019-01-09T06:44:10Z",
        "goVersion": "go1.10.3",
        "compiler": "gc",
        "platform": "linux/amd64"
        }
    2. Verify that you can access the cluster machine configuration, by running the following command and observing the output:

      $ curl -v https://api.<cluster_name>.<base_domain>:22623/healthz --insecure

      If the configuration is correct, the output from the command shows the following response:

      HTTP/1.1 200 OK
      Content-Length: 0
    3. Verify that you can access each cluster application on port, by running the following command and observing the output:

      $ curl http://console-openshift-console.apps.<cluster_name>.<base_domain> -I -L --insecure

      If the configuration is correct, the output from the command shows the following response:

      HTTP/1.1 302 Found
      content-length: 0
      location: https://console-openshift-console.apps.<cluster-name>.<base domain>/
      cache-control: no-cacheHTTP/1.1 200 OK
      referrer-policy: strict-origin-when-cross-origin
      set-cookie: csrf-token=39HoZgztDnzjJkq/JuLJMeoKNXlfiVv2YgZc09c3TBOBU4NI6kDXaJH1LdicNhN1UsQWzon4Dor9GWGfopaTEQ==; Path=/; Secure
      x-content-type-options: nosniff
      x-dns-prefetch-control: off
      x-frame-options: DENY
      x-xss-protection: 1; mode=block
      date: Tue, 17 Nov 2020 08:42:10 GMT
      content-type: text/html; charset=utf-8
      set-cookie: 1e2670d92730b515ce3a1bb65da45062=9b714eb87e93cf34853e87a92d6894be; path=/; HttpOnly; Secure; SameSite=None
      cache-control: private
    4. Verify that you can access each cluster application on port 443, by running the following command and observing the output:

      $ curl https://console-openshift-console.apps.<cluster_name>.<base_domain> -I -L --insecure

      If the configuration is correct, the output from the command shows the following response:

      HTTP/1.1 200 OK
      referrer-policy: strict-origin-when-cross-origin
      set-cookie: csrf-token=UlYWOyQ62LWjw2h003xtYSKlh1a0Py2hhctw0WmV2YEdhJjFyQwWcGBsja261dGLgaYO0nxzVErhiXt6QepA7g==; Path=/; Secure; SameSite=Lax
      x-content-type-options: nosniff
      x-dns-prefetch-control: off
      x-frame-options: DENY
      x-xss-protection: 1; mode=block
      date: Wed, 04 Oct 2023 16:29:38 GMT
      content-type: text/html; charset=utf-8
      set-cookie: 1e2670d92730b515ce3a1bb65da45062=1bf5e9573c9a2760c964ed1659cc1673; path=/; HttpOnly; Secure; SameSite=None
      cache-control: private