- Getting Started
- Support for K8s Installers
- Deploying on Kind
- Deploying on Minikube
- Antrea Network Policy
- Traffic Encryption (Ipsec / WireGuard)
- Securing Control Plane
- Security considerations
- OS-specific Known Issues
- OVS Pipeline
- Feature Gates
- Network Flow Visibility
- Traceflow Guide
- NoEncap and Hybrid Traffic Modes
- Egress Guide
- NodePortLocal Guide
- Antrea IPAM Guide
- Exposing Services of type LoadBalancer
- Antrea API Groups
- Antrea API Reference
Service of type LoadBalancer
Table of Contents
- Service external IP management by Antrea
- Using MetalLB with Antrea
In Kubernetes, implementing Services of type LoadBalancer usually requires an external load balancer. On cloud platforms (including public clouds and platforms like NSX-T) that support load balancers, Services of type LoadBalancer can be implemented by the Kubernetes Cloud Provider, which configures the cloud load balancers for the Services. However, the load balancer support is not available on all platforms, or in some cases, it is complex or has extra cost to deploy external load balancers. This document describes two options for supporting Services of type LoadBalancer with Antrea, without an external load balancer:
- Using Antrea’s built-in external IP management for Services of type LoadBalancer
- Leveraging MetalLB
Service external IP management by Antrea
Antrea supports external IP management for Services of type LoadBalancer
since version 1.5, which can work together with
kube-proxy to implement Services of type LoadBalancer, without requiring an
external load balancer. With the external IP management feature, Antrea can
allocate an external IP for a Service of type LoadBalancer from an
ExternalIPPool, and select a Node
based on the ExternalIPPool’s NodeSelector to host the external IP. Antrea
configures the Service’s external IP on the selected Node, and thus Service
requests to the external IP will get to the Node, and they are then handled by
kube-proxy on the Node and distributed to the Service’s
Endpoints. Antrea also implements a Node failover mechanism for Service
external IPs. When Antrea detects a Node hosting an external IP is down, it
will move the external IP to another available Node of the ExternalIPPool.
Enable Service external IP management feature
At this moment, external IP management for Services is an alpha feature of
ServiceExternalIP feature gate of
antrea-controller must be enabled for the feature to work. You can enable
ServiceExternalIP feature gate in the
antrea-config ConfigMap in
the Antrea deployment YAML:
kind: ConfigMap apiVersion: v1 metadata: name: antrea-config-dcfb6k2hkm namespace: kube-system data: antrea-agent.conf: | featureGates: ... ServiceExternalIP: true ... antrea-controller.conf: | featureGates: ... ServiceExternalIP: true ...
The feature works with both
kube-proxy, including the
proxyAllenabled - this is
antrea-agent’s default configuration, in which
kube-proxyserves the request traffic for Services of type LoadBalancer (while
AntreaProxyhandles Service requests from Pods).
proxyAllenabled - in this case,
AntreaProxyhandles all Service traffic, including Services of type LoadBalancer.
kube-proxyhandles all Service traffic, including Services of type LoadBalancer.
Create an ExternalIPPool custom resource
Service external IPs are allocated from an ExternalIPPool, which defines a pool of external IPs and the set of Nodes to which the external IPs can be assigned. To learn more information about ExternalIPPool, please refer to the Egress documentation. The example below defines an ExternalIPPool with IP range “10.10.0.2 - 10.10.0.10”, and it selects the Nodes with label “network-role: ingress-node” to host the external IPs:
- apiVersion: crd.antrea.io/v1alpha2 kind: ExternalIPPool metadata: name: service-external-ip-pool spec: ipRanges: - start: 10.10.0.2 end: 10.10.0.10 - cidr: 10.10.1.0/28 nodeSelector: matchLabels: network-role: ingress-node
Create a Service of type LoadBalancer
For Antrea to manage the externalIP for a Service of type LoadBalancer, the
Service should be annotated with
apiVersion: v1 kind: Service metadata: name: my-service annotations: service.antrea.io/external-ip-pool: "service-external-ip-pool" spec: selector: app: MyApp ports: - protocol: TCP port: 80 targetPort: 9376 type: LoadBalancer
You can also request a particular IP from an ExternalIPPool by setting the loadBalancerIP field in the Service spec to that specific IP available in the ExternalIPPool, Antrea will allocate the IP from the ExternalIPPool for the Service. For example:
apiVersion: v1 kind: Service metadata: name: my-service annotations: service.antrea.io/external-ip-pool: "service-external-ip-pool" spec: selector: app: MyApp loadBalancerIP: "10.10.0.2" ports: - protocol: TCP port: 80 targetPort: 9376 type: LoadBalancer
Validate Service external IP
Once Antrea allocates an external IP for a Service of type LoadBalancer, it
will set the IP to the
loadBalancer.ingress field in the Service resource
status. For example:
apiVersion: v1 kind: Service metadata: name: my-service annotations: service.antrea.io/external-ip-pool: "service-external-ip-pool" spec: selector: app: MyApp ports: - protocol: TCP port: 80 targetPort: 9376 clusterIP: 10.96.0.11 type: LoadBalancer status: loadBalancer: ingress: - ip: 10.10.0.2 hostname: node-1
You can validate that the Service can be accessed from the client using the
<external IP>:<port> (
10.10.0.2:80/TCP in the above example).
As described above, the Service externalIP management by Antrea configures a Service’s external IP to a Node, so that the Node can receive Service requests. However, this requires that the externalIP on the Node be reachable through the Node network. The simplest way to achieve this is to reserve a range of IPs from the Node network subnet, and define Service ExternalIPPools with the reserved IPs, when the Nodes are connected to a layer 2 subnet. Or, another possible way might be to manually configure Node network routing (e.g. by adding a static route entry to the underlay router) to route the Service traffic to the Node that hosts the Service’s externalIP.
As of now, Antrea supports Service externalIP management only on Linux Nodes. Windows Nodes are not supported yet.
Using MetalLB with Antrea
MetalLB also implements external IP management for Services of type LoadBalancer, and it can be deployed to a Kubernetes cluster with Antrea. MetalLB supports two modes - layer 2 mode and BGP mode - to advertise an Service external IP to the Node network. The layer 2 mode is similar to what Antrea external IP management implements and has the same limitation that the external IPs must be allocated from the Node network subnet. The BGP mode leverages BGP to advertise external IPs to the Node network router. It does not have the layer 2 subnet limitation, but requires the Node network to support BGP.
MetalLB will automatically allocate external IPs for every Service of type
LoadBalancer, and it sets the allocated IP to the
in the Service resource
status. MetalLB also supports user specified
in the Service spec. For more information, please refer to the
To learn more about MetalLB concepts and functionalities, you can read the MetalLB concepts.
You can run the following commands to install MetalLB using the YAML manifests:
kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.11.0/manifests/namespace.yaml kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.11.0/manifests/metallb.yaml
The commands will deploy MetalLB of version 0.11.0 into Namespace
metallb-system. You can also refer to this
MetalLB installation guide
for other ways of installing MetalLB.
As MetalLB will allocate external IPs for all Services of type LoadBalancer,
once it is running, the Service external IP management feature of Antrea should
not be enabled to avoid conflicts with MetalLB. You can deploy Antrea with the
default configuration (in which the
ServiceExternalIP feature gate of
antrea-agent is set to
false). MetalLB can work with both
kube-proxy configurations of
Configure MetalLB with layer 2 mode
MetalLB is configured through a ConfigMap. To configure MetalLB to work in the layer 2 mode, you just need to provide the IP ranges to allocate external IPs. The IP ranges should be from the Node network subnet.
apiVersion: v1 kind: ConfigMap metadata: namespace: metallb-system name: config data: config: | address-pools: - name: default protocol: layer2 addresses: - 10.10.0.2-10.10.0.10
Configure MetalLB with BGP mode
The BGP mode of MetalLB requires more configuration parameters to establish BGP peering to the router. The example below configures MetalLB using AS number 64500 to connect to peer router 10.0.0.1 with AS number 64501:
apiVersion: v1 kind: ConfigMap metadata: namespace: metallb-system name: config data: config: | peers: - peer-address: 10.0.0.1 peer-asn: 64501 my-asn: 64500 address-pools: - name: default protocol: bgp addresses: - 10.10.0.2-10.10.0.10
In addition to the basic layer 2 and BGP mode configurations described in this document, MetalLB supports a few more advanced BGP configurations and supports configuring multiple IP pools which can use different modes. For more information, please refer to the MetalLB configuration guide.