Avi Kubernetes Operator Deployment Guide
The Avi Kubernetes Operator (AKO) is an operator which works as an Ingress controller and performs Avi-specific functions in a Kubernetes/ OpenShift environment with the Avi Controller. It translates Kubernetes/ OpenShift objects to Avi Controller APIs.
This guide helps you understand the architectural overview and design considerations for AKO deployment.
The Avi Deployment in Kubernetes/ OpenShift for AKO comprises of the following main components:
- The Avi Controller
- The Service Engines (SE)
- The Avi Kubernetes Operator (AKO)
The Avi Controller
The Avi Controller which is the central component of the Avi architecture is responsible for the following:
- Control plane functionality like the:
- Infrastructure orchestration
- Centralized management
- Analytics dashboard
- Integration with the underlying ecosystem for managing the lifecycle of the data plane (Service Engines).
The Avi Controller does not handle any data plane traffic.
In Kubernetes/ OpenShift environments, the Avi Controller is deployed outside the Kubernetes/ OpenShift cluster, typically in the native type of the underlying infrastructure. However, it can be deployed anywhere as long as connectivity and latency requirements are satisfied.
The Avi Service Engines
The SEs implement data plane services of load balancing. For example, Web Application Firewall, DNS/GSLB, etc.
In Kubernetes/ OpenShift environments, the SEs are deployed external to the cluster and typically in the native type of the underlying infrastructure.
The Avi Kubernetes Operator (AKO)
AKO is an Avi pod running in Kubernetes that provides an Ingress controller and Avi-configuration functionality.
AKO remains in sync with the required Kubernetes/ OpenShift objects and calls the Avi Controller APIs to deploy the Ingresses and Services via the Avi Service Engines.
AKO is deployed as a pod via Helm.
Avi Cloud Considerations
Avi Cloud Type
The Avi Controller uses the Avi Cloud configuration to manage the SEs. This Avi Cloud is usually of the underlying infrastructure type, for ex. VMware vCenter Cloud, Azure Cloud, Linux Server Cloud etc.
Note: This deployment in Kubernetes/ OpenShift does not use the Kubernetes/ OpenShift cloud types. The integration with Kubernetes/ OpenShift and application-automation functions are handled by AKO and not by the Avi Controller.
Multiple Kubernetes/ OpenShift Clusters
A single Avi Cloud can be used for integration with multiple Kubernetes/ OpenShift clusters, with each cluster running its own instance of AKO. Clusters in the
clusterIP mode are separated on the data plane through unique SE groups per cluster.
IPAM and DNS
The IPAM and DNS functionality is handled by the Avi Controller via the Avi cloud configuration.
Refer to the Service Discovery Using IPAM and DNS article for more information on supported IPAM and DNS types per environment.
Service Engine Groups
Starting with version 1.2.1, AKO supports a separate SE group per Kubernetes/OpenShift cluster. Each cluster will need to be configured with a separate SE group. However, multiple SE groups within the same cluster is not supported. As a best practice, it is recommended to use non-default SE groups for every cluster. SE group per cluster is not a requirement if AKO runs in the
Avi Controller Version
AKO version 1.2.1 supports Avi Controller releases 18.2.10, 20.1.1 and above only.
Versions prior to 18.2.10 are not supported.
Avi SE Placement / Pod Network Reachability
With AKO, the service engines are deployed outside the cluster. To be able to load balance requests directly to the pods, the pod CIDR must be routable from the SE. Depending on the routability of the Pod CNI used in the cluster, AKO can route using the following options:
Pods are not Externally Routable – Static Routing
For CNIs like Canal, Calico, Antrea, Flannel etc., the pod subnet is not externally routable. In these cases, the CNI assigns a pod CIDR to each node in the Kuberntes cluster. The pods on a node get IP assigned from the CIDR allocated for that node and is routable from within the node. In this scenario, the pod reachability depends on where the SE is placed.
If SE is placed on the same network as the Kubernetes/ OpenShift nodes, you can turn on static route programming in AKO. With this, AKO syncs the pod CIDR for each Kubernetes/ OpenShift node and programs static route on the Avi Controller for each Pod CIDR with the Kubernetes/ OpenShift node IP as the next hop. Prior to AKO 1.2.1 static routing per cluster for Pod Networks leveraged VRFs. Starting with AKO 1.2.1, static routing per cluster uses a new label-based routing scheme. No additional user configuration is required for this label-based scheme, however the upgrade from AKO 1.1.1 to 1.2.1 will be service impacting requiring an AKO restart.
Pods are not externally routable – NodePort
In cases where direct load-balancing to the pods is not possible, NodePort based services can be used as the pool members in the Avi virtual service as end points. For this functionality, configure the services referenced by Ingresses/Routes as type NodePort and set the
configs.serviceType parameter to enable NodePort based Routes/Ingresses. The
nodeSelectorLabels.value parameters are specified during the AKO installation to select the required Nodes from the cluster for load balancing. The required nodes in the cluster need to be labelled with the configured key and value pair.
Pod Subnet is Routable
For CNIs like NSX-T CNI, AWS CNI (in EKS), Azure CNI (in AKS) etc., the pod subnet is externally routable. In this case no additional configuration is required to allow SEs to reach the Pod IPs. Set Static Route Programming to Off in the AKO configuration. SEs can be placed on any network and will be able to route the pods.
To know more about the CNIs supported in AKO version 1.2.1 click here.
Single Arm Deployment
AKO version 1.2.1 supports both Single-Arm and Two-Arm deployments with vCenter Cloud in write-access mode.
Handling of Kubernetes/ OpenShift and Avi Objects
This section outlines the object translation logic between AKO and the Avi Controller.
Service of Type Load Balancer
AKO creates a Layer 4 virtual service object in Avi corresponding to a service of type
loadbalancer in Kubernetes/ OpenShift.
An example of such a service object in Kubernetes/ OpenShift is as follows:
apiVersion: v1 kind: Service metadata: name: avisvc-lb namespace: red spec: type: LoadBalancer ports: - port: 80 targetPort: 8080 name: eighty selector: app: avi-server
AKO creates a dedicated virtual service for this object in Kubernetes/ OpenShift that refers to reserving a virtual IP for it. The layer 4 virtual service uses a pool section logic based on the ports configured on the service of type
loadbalancer. In this case, the incoming port is port 80 and hence the virtual service listens on this port for client requests.
AKO selects the pods associated with this service as pool servers associated with the virtual service.
Service of Type Load Balancer with Preferred IP
The Kubernetes service objects allow Controllers/cloud providers to create services with user-specified IPs using the
loadBalancerIP field. AKO supports the
loadBalancerIP field usage where-in the corresponding Layer 4 virtual service objects are created with the user provided IP.
apiVersion: v1 kind: Service metadata: name: avisvc-lb namespace: red spec: loadBalancerIP: 10.10.10.11 type: LoadBalancer ports: - port: 80 targetPort: 8080 name: eighty selector: app: avi-server
Avi Vantage does not allow updating preferred virtual IPs bound to a particular virtual service. Therefore, to update the user preferred IP, it is required to re-create the service object, failing which Avi/AKO throws an error. The following transition cases should be kept in mind, and for these, an explicit service re-create with configuration updates is required.
- Updating loadBalancerIP value, from
loadBalancerIPvalue after the Service is assigned an IP from Avi
loadBalancerIPvalue after the Service is assigned an IP from Avi
Recreating the service object deletes the Layer 4 virtual service in Avi Vantage, frees up the applied virtual IP and post that the service creation with the updated configuration results in the intended virtual service configuration.
Service of Type NodePort
A service of Type NodePort can be used to send traffic to the pods using nodeports. This can be used where the option of static IP in VRF Context is not feasible.
This feature supports ingress/route attached to Service of type
AKO will function either in the NodePort mode or in ClusterIP mode.
A new parameter serviceType has been introduced as configuration in AKO’s values.yaml.
To use this feature, set the
|configs.serviceType||Type of Service to be used as backend for Routes/Ingresses||ClusterIP|
|nodeSelectorLabels.key||Key used as a label based selection for the nodes in NodePort mode|
|nodeSelectorLabels.value||Value used as a label based selection for the nodes in NodePort mode|
By default, Kubernetes/ OpenShift configures the node port for any service of type
config.serviceType is set to
NodePort, AKO would use NodePort as backend for service of type Loadbalancer instead of using Endpoints.
This is the default behaviour with
config.serviceType set to
Consider the following example of an insecure hostname specification from a Kubernetes Ingress object:
apiVersion: networking.k8s.io/v1beta1 kind: Ingress metadata: name: my-ingress spec: rules: - host: myinsecurehost.avi.internal http: paths: - path: /foo backend: serviceName: service1 servicePort: 80
For insecure host/path combinations, AKO uses a Sharded virtual service logic. Here, based on either the namespace of this Ingress or the hostname value (myhost.avi.internal), a pool object is created on a Shared virtual service. A shared virtual service typically denotes a virtual service in Avi that is shared across multiple Ingresses.
A priority label is associated to the pool group against its member pool (that is created as a part of this Ingress), with the priority label
An associated DataScript object with this shared virtual service is used to interpret the host FQDN/path combination of the incoming request. The corresponding pool is chosen based on the priority label as mentioned above.
The path matches are by default Longest Prefix Matches (LPM). This means for this particular host/path if pool X is created then, the matchrule can be interpreted as - “If the host header equals myhost.avi.internal and path STARTSWITH foo then route the request to pool X”. However, a “/” path on the FQDN can still be programmed to point uniquely to a different pool without conflicts.
Consider the following example of an secure Ingress object:
apiVersion: networking.k8s.io/v1beta1 kind: Ingress metadata: name: my-ingress spec: tls: - hosts: - myhost.avi.internal secretName: testsecret-tls rules: - host: myhost.avi.internal http: paths: - path: /foo backend: serviceName: service1 servicePort: 80
SNI Virtual Service per Secure Hostname
AKO creates an SNI child virtual service to a parent shared virtual service for the secure hostname. The SNI virtual service is used to bind the hostname to an
sslkeycert object. The
sslkeycert object is used to terminate the secure traffic on Avi’s service engine. In the above example the
secretName field denotes the secret asssociated with the hostname
myhost.avi.internal. AKO parses the attached secret object and appropriately creates the
sslkeycert object in Avi. The SNI virtual service does not get created if the secret object does not exist in Kubernetes corresponding to the reference specified in the Ingress object.
Traffic Routing Post SSL Termination
On the SNI virtual service, AKO creates
httppolicyset rules to route the terminated (insecure) traffic to the appropriate pool object using the host/path specified in the rules section of this Ingress object.
Redirect Secure Hosts from HTTP to HTTPS
Additionally, for these hostnames, AKO creates a redirect policy on the shared virtual service (parent to the SNI child) for this specific secure hostname. This allows the client to automatically redirect the HTTP requests to HTTPS if they are accessed on the insecure port (80).
In Openshift cluster, AKO can be used to configure routes. Ingress configuration is not supported. Currently the shard mode supported for openshift route is hostname.
apiVersion: v1 kind: Route metadata: name: route1 spec: host: routehost1.avi.internal path: /foo to: kind: Service name: avisvc1
For insecure routes, AKO creates a Shared virtual service, pool group, and DataScript like insecure ingress. For pool name, the route configuration differs from ingress configuration. The service name is appended at the end of pool name.
Shared Virtual Service Pool Names for Route
The formula to derive the Shared virtual service pool name for route is as follows:
poolname = clusterName + "--" + hostname + "-" + namespace + "-" + routeName + "-" + serviceName
Insecure Route with Alternate Backends
A route can also be associated with multiple services denoted by alternate backends. The requests that are handled by each service is governed by the service weight.
apiVersion: v1 kind: Route metadata: name: route1 spec: host: routehost1.avi.internal path: /foo to: kind: Service name: avisvc1 weight: 20 alternateBackends: - kind: Service name: avisvc2 weight: 10
For each backend of a route, a new pool is added. All such pools are added with same priority label -
hostname/path. In case of the example mentioned above, two pools would be added with priority -
The ratio for a pool is the same as the weight specified for the service in the route.
Secure Route with Edge Termination
apiVersion: v1 kind: Route metadata: name: secure-route1 spec: host: secure1.avi.internal path: /bar to: kind: Service name: avisvc1 tls: termination: edge key: |- -----BEGIN RSA PRIVATE KEY----- ... ... -----END RSA PRIVATE KEY----- certificate: |- -----BEGIN CERTIFICATE----- ... ... -----END CERTIFICATE-----
Secure route is configured in Avi like secure ingress. An SNI virtual service is created for each hostname and for each host path, one pool group is created. However, for alternate backends, multiple pools are added in each pool group. Also, unlike Secure Ingresses, no redirect policy is configured for secure route for insecure traffic.
SNI Pool Names for Route
The formula to derive the SNI virtual service’s pools for route is as follows:
poolname = clusterName + "--" + namespace + "-" + hostname + "_" + path + "-" + routeName + "-" serviceName
Secure Route with Termination Reencrypt
apiVersion: v1 kind: Route metadata: name: secure-route1 spec: host: secure1.avi.internal to: kind: Service name: service-name tls: termination: reencrypt key: |- -----BEGIN PRIVATE KEY----- [...] -----END PRIVATE KEY----- certificate: |- -----BEGIN CERTIFICATE----- [...] -----END CERTIFICATE----- destinationCACertificate: |- -----BEGIN CERTIFICATE----- [...] -----END CERTIFICATE-----
In case case of reencrypt, an SNI virtual service is created for each hostname and each host/path combination corresponds to a pool group in Avi. SSL is enabled in each pool for such virtual services with SSL profile set to
System-Standard. In additon, if the
destinationCACertificate is specified, a PKI profile with the
destinationCACertificate is created for each pool.
Secure Route Insecure Edge Termination Policy: Redirect
apiVersion: v1 kind: Route metadata: name: secure-route1 spec: host: secure1.avi.internal to: kind: Service name: service-name tls: termination: edge insecureEdgeTerminationPolicy: redirect key: |- -----BEGIN PRIVATE KEY----- [...] -----END PRIVATE KEY----- certificate: |- -----BEGIN CERTIFICATE----- [...] -----END CERTIFICATE-----
In addition to the secure SNI virtual service, for this type of route, AKO creates a redirect policy on the shared parent of the SNI child for this specific secure hostname. This allows the client to automatically redirect the http requests to https if they are accessed on the insecure port (80).
Secure Route Insecure Edge Termination Policy: Allow
apiVersion: v1 kind: Route metadata: name: secure-route1 spec: host: secure1.avi.internal to: kind: Service name: service-name tls: termination: edge insecureEdgeTerminationPolicy: Allow key: |- -----BEGIN PRIVATE KEY----- [...] -----END PRIVATE KEY----- certificate: |- -----BEGIN CERTIFICATE----- [...] -----END CERTIFICATE-----
insecureEdgeTerminationPolicy is Allow, then AKO creates an SNI VS for the hostname; also a pool is created for the same hostname which is added as member is pool group of the parent Shared virtual service. This enables the host to be accessed via both http(80) and https(443) port.
With passthrough routes, secure traffic is sent to the backend pods without TLS termination in AVI. A set of shared L4 Virtual Services are created by AKO to handle all TLS passthrough routes. Number of shards can be configured in helm with the flag
passthroughShardSize in values.yaml. These virtual services would listen on port 443 and have one L4 ssl datascript each. Name of the virtual service would be of the format
'Shared-Passthrough'-shardnumber. A number of shards can be configured using the flag
passthroughShardSize while installation using helm.
apiVersion: v1 kind: Route metadata: name: passthrough-route1 spec: host: pass1.avi.internal to: kind: Service name: service-name tls: termination: edge insecureEdgeTerminationPolicy: Allow
For each passthrough host, one unique pool group is created with name
clustername-fqdn and the pool group is attached to the DataScript of the virtual service that is derived by the sharding logic. In this case, a pool group with name
clustername-pass1.avi.internal is created.
For each backend of a TLS passthrough route, one pool is created with ratio as per the route spec and is attached to the corresponding pool group.
insecureEdgeTerminationPolicy is redirect, another virtual service is created for each shared L4 VS, to handle insecure traffic on port 80. HTTP Request polices would be added in this VS for each FQDN with
insecureEdgeTermination policy set to redirect. Both the virtual services listening on port 443 and 80 have a common virtual service VIP. This allows the DNS virtual service to resolve the hostname to one IP address consistently. The name of the insecure shared virtual service would be of the format
For passthrough routes, the
insecureEdgeTerminationPolicy: Allow is not supported in OpenShift.
Multi-Port Service Support in Openshift
A service in OpenShift can have multiple ports. In order for a Service to have multiple ports, OpenShift mandates them to have a name. To use such a service, the user must specify the
targetPort within the port in route spec. The value of the
targetPort can be integer value of the target port or name of the port. If the backend service has only one port, then the port field in route can be skipped, but it can not be skipped if the service has multiple ports. For example, consider the following service:
apiVersion: v1 kind: Service metadata: labels: run: avisvc spec: ports: - name: myport1 port: 80 protocol: TCP targetPort: 80 - name: myport2 port: 8080 protocol: TCP targetPort: 8080 selector: app: my-app type: ClusterIP
In order to use this service in a route, the route spec can look like one of the following:
apiVersion: v1 kind: Route metadata: name: route1 spec: host: routehost1.avi.internal path: /foo port: targetPort: 8080 to: kind: Service name: avisvc1 apiVersion: v1 kind: Route metadata: name: route1 spec: host: routehost1.avi.internal path: /foo port: targetPort: myport2 to: kind: Service name: avisvc1
BGP RHI Support
A Border Gateway Protocol (BGP) feature, route health injection (RHI), allows the Avi Service engines to publish the VIP to the SE interface mapping to the upstream BGP peers.
Using BGP, a virtual service enabled for RHI can be placed on up to 64 SEs within the SE group. Each SE uses RHI to advertise a /32 host route to the virtual service’s VIP address, and accepts the traffic.
The upstream router uses Equal cost multi-path (ECMP) to select a path to one of the SEs. The BGP peer connected to the Avi SE updates its route table to use the Avi SE as the next hop for reaching the VIP. The peer BGP router also advertises itself to its upstream BGP peers as a next hop for reaching the VIP. The BGP peer IP addresses, the local Autonomous System (AS) number other settings, are specified in a BGP profile on the Avi Controller.
This feature is disabled by default.
To publish route information to BGP peers, set
NetworkSettings.enableRHI to True.
Note: On setting
NetworkSettings.enableRHI to True, this configuration is applied to all virtual services created by AKO.
Since RHI is a Layer 4 construct, the setting applies to all the host FQDNs patched as pools/SNI virtual services to the parent shared virtual service.
AKO Created Object Naming Conventions
In the current AKO model, all Kubernetes/ OpenShift cluster objects are created on the admin tenant in Avi. This is true even for multiple Kubernetes/ OpenShift clusters managed through a single Avi cloud (like the vCenter cloud).
Each virtual service/pool/pool group has to be unique to ensure there are no conflicts between similar object types.
AKO uses a combination of elements from each Kubernetes/ OpenShift object to create a corresponding object in Avi that is unique for the cluster.
L4 Virtual Service
Use the following formula to derive a virtual service name:
vsName = clusterName + "--" + namespace + "--" + svcName
vrfNameis the value specified in values.yaml during install.
svcNamerefers to the service object’s name in Kubernetes/ OpenShift.
namespacerefers to the namespace on which the service object is created.
Use the following formula to derive L4 pool names:
poolname = vsName + "-" + listener_port
listener_portrefers to the service port on which the virtual service listens on.
- The number of pools is directly associated with the number of listener ports configured in the Kubernetes/ OpenShift service object.
L4 Pool Group
Use the following formula to derive the L4 pool group names for L4 virtual services:
poolgroupname = vsName + "-" + listener_port
vsNameis the virtual service’s name.
listener_portrefers to the service port on which the virtual service listens on.
Shared Virtual Service
The shared virtual service names are derived based on a combination of fields to keep it unique per Kubernetes/ OpenShift cluster. This is the only object in Avi that does not derive it’s name from any of the Kubernetes/ OpenShift objects.
The formula to derive the shared virtual service name is as follows:
ShardVSName = clusterName + "--Shared-L7-" + <shardNum>
clusterNameis the value specified in values.yaml during install.
shardNumis the number of the shared VS generated based on either hostname or namespace based shards.
Shared Virtual Service Pool
Use the following formula to derive the Shared virtual service pool group name:
poolgroupname = clusterName + "--" + priorityLabel + "-" + namespace + "-" + ingName
clusterNameis the value specified in values.yaml during install.
priorityLabelis the host/path combination specified in each rule of the Kubernetes Ingress object.
ingNamerefers to the name of the ingress object.
namespacerefers to the namespace on which the ingress object is found in Kubernetes.
Shared Virtual Service Pool Group
Use the following formula to derive the shared virtual service pool group name:
poolgroupname = vsName
vsNameis the virtual service’s name.
Name of the shared virtual service is the same as the shared virtual service name.
SNI Child Virtual Service
The SNI child virtual service’s naming varies between different sharding options.
vsName = clusterName + "--" + sniHostName
vsName = clusterName + "--" + ingName + "-" + namespace + "-" + secret
The difference in naming is done because with namespace based sharding only one SNI child is created per ingress/per secret object but in hostname based sharding each SNI virtual service is unique to the hostname specified in the Ingress object.
Use the following formula to derive the SNI virtual service’s pool names:
poolname = clusterName + "--" + namespace + "-" + host + "_" + path + "-" + ingName
Here, the host and path variables denote the secure hosts’ hostname and path specified in the ingress object.
SNI Pool Group
Use the following formula to derive the SNI virtual service’s pool group names:
poolgroupname = clusterName + "--" + namespace + "-" + host + "_" + path + "-" + ingName
Some of these naming conventions can be used to debug/derive corresponding Avi object names that can be used as a tool for first level troubleshooting.
AKO version 1.3.1 does not support annotations. However, the
HostRule CRDs can be leveraged to customize the Avi configuration. Refer to the Custom Resource Definitions article for more information on what parameters can be tweaked.
AKO version 1.3 supports multi-tenancy.
Refer to the the Compatibility Guide for information on supportability of features and environments with AKO.
The following features are supported in AKO version 1.3.1:
|AKO install/ upgrade||Helm|
|Service sync of type L4||AKO|
|Ingress sync of type L7||AKO|
|SE static route programming||AKO|
Document Revision History
|December 18, 2020||Updated the Design Guide for AKO version 1.3.1|
|September 18, 2020||Published the Design Guide for AKO version 1.2.1|
|July 20, 2020||Published the Design Guide for AKO version 1.2.1 (Tech Preview)|