Load balancing on OpenStack | Networking

Using the Octavia OVN load balancer provider driver with Kuryr SDN
Scaling clusters for application traffic by using Octavia
- Scaling clusters by using Octavia
- Scaling clusters that use Kuryr by using Octavia
Scaling for ingress traffic by using OpenStack Octavia
Configuring an external load balancer

Using the Octavia OVN load balancer provider driver with Kuryr SDN

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:

Open the kuryr-config ConfigMap. On a command line, enter:
```
$ oc -n openshift-kuryr edit cm kuryr-config
```
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.

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
...

Verify that OpenStack recreated its load balancers.

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

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

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.
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.

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

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

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

Optional: To reuse the cluster API floating IP address, unset it:
```
$ openstack floating ip unset $API_FIP
```

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

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

Optional: From a command line, to reuse the cluster API floating IP address, unset it:
```
$ openstack floating ip unset $API_FIP
```

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

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

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

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.

From a command line, create a service from the external_router.yaml file:
```
$ oc apply -f external_router.yaml
```

Verify that the external IP address of the service is the same as the one that is associated with the load balancer:

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

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 |

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.

Prerequisites

On your load balancer, TCP over ports 6443, 443, and 80 must be available to any users of your system.
Load balance the API port, 6443, between each of the control plane nodes.
Load balance the application ports, 443 and 80, between all of the compute nodes.
On your load balancer, port 22623, which is used to serve ignition startup configurations to nodes, is not exposed outside of the cluster.
Your load balancer must be able to access every machine in your cluster. Methods to allow this access include:
- Attaching the load balancer to the cluster’s machine subnet.
- Attaching floating IP addresses to machines that use the load balancer.

Procedure

Enable access to the cluster from your load balancer on ports 6443, 443, and 80.

As an example, note this HAProxy configuration:

A section of a sample HAProxy configuration

...
listen my-cluster-api-6443
    bind 0.0.0.0:6443
    mode tcp
    balance roundrobin
    server my-cluster-master-2 192.0.2.2:6443 check
    server my-cluster-master-0 192.0.2.3:6443 check
    server my-cluster-master-1 192.0.2.1:6443 check
listen my-cluster-apps-443
        bind 0.0.0.0:443
        mode tcp
        balance roundrobin
        server my-cluster-worker-0 192.0.2.6:443 check
        server my-cluster-worker-1 192.0.2.5:443 check
        server my-cluster-worker-2 192.0.2.4:443 check
listen my-cluster-apps-80
        bind 0.0.0.0:80
        mode tcp
        balance roundrobin
        server my-cluster-worker-0 192.0.2.7:80 check
        server my-cluster-worker-1 192.0.2.9:80 check
        server my-cluster-worker-2 192.0.2.8:80 check

Add records to your DNS server for the cluster API and apps over the load balancer. For example:

<load_balancer_ip_address> api.<cluster_name>.<base_domain>
<load_balancer_ip_address> apps.<cluster_name>.<base_domain>

From a command line, use curl to verify that the external load balancer and DNS configuration are operational.

Verify that the cluster API is accessible:

$ 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"
}

Verify that cluster applications are accessible:

You can also verify application accessibility by opening the OKD console in a web browser.

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

If the configuration is correct, you receive an HTTP 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