VPC Egress Gateway¶
Note
Subnets under custom VPCs do not support distributed gateways and centralized gateways under default VPCs.
Currently, custom VPCs support three solutions for external network connectivity: VPC NAT Gateway, OVN Gateway, and Egress Gateway. Among them, VPC NAT Gateway is the earliest supported egress method by Kube-OVN, creating a multi-NIC Pod for each VPC NAT Gateway, with one NIC connected to the custom VPC network and another NIC connected to the underlying physical network through Macvlan, implementing various ingress/egress operations through iptables within the Pod. This method currently supports the most features and has been used for the longest time, but it also has the disadvantages of single point of failure and complex usage.
OVN Gateway uses various NAT capabilities natively supported within OVN to implement ingress/egress, which can improve performance through hardware acceleration and achieve failover through OVN's built-in BFD. Since it exposes OVN's native concepts, users need to be fairly familiar with OVN's application.
Egress Gateway is an improvement to address the single point issue of VPC NAT Gateway, implementing horizontal scaling and fast failover, but currently only implements egress capability without ingress capability.
VPC Egress Gateway is used to control external network access for Pods within a VPC (including the default VPC) with a group of static addresses and has the following features:
- Achieves Active-Active high availability through ECMP, enabling horizontal throughput scaling
- Implements fast failover (<1s) via BFD
- Supports IPv6 and dual-stack
- Enables granular routing control through
NamespaceSelectorandPodSelector - Allows flexible scheduling of Egress Gateway through
NodeSelector
At the same time, VPC Egress Gateway has the following limitations:
- Uses macvlan for underlying network connectivity, requiring Underlay support from the underlying network
- In multi-instance Gateway mode, multiple Egress IPs are required
- Currently, only supports SNAT; EIP and DNAT are not supported
- Currently, recording source address translation relationships is not supported
Implementation Details¶
Each Egress Gateway consists of multiple Pods with multiple network interfaces. Each Pod has two network interfaces: one joins the virtual network for communication within the VPC, and the other connects to the underlying physical network via Macvlan for external network communication. Virtual network traffic ultimately accesses the external network through NAT within the Egress Gateway instances.
Each Egress Gateway instance registers its address in the OVN routing table. When a Pod within the VPC needs to access the external network, OVN uses source address hashing to forward traffic to multiple Egress Gateway instance addresses, achieving load balancing. As the number of Egress Gateway instances increases, throughput can also scale horizontally.
OVN uses the BFD protocol to probe multiple Egress Gateway instances. When an Egress Gateway instance fails, OVN marks the corresponding route as unavailable, enabling rapid failure detection and recovery.
Requirements¶
The VPC Egress Gateway is the same as the VPC NAT Gateway in that it requires Multus-CNI.
No ConfigMap needs to be configured to use VPC Egress Gateway.
Usage¶
Creating a Network Attachment Definition¶
The VPC Egress Gateway uses multiple NICs to access both the VPC and the external network, so you need to create a Network Attachment Definition to connect to the external network. An example of using the macvlan plugin with IPAM provided by Kube-OVN is shown below:
apiVersion: k8s.cni.cncf.io/v1
kind: NetworkAttachmentDefinition
metadata:
name: eth1
namespace: default
spec:
config: '{
"cniVersion": "0.3.0",
"type": "macvlan",
"master": "eth1",
"mode": "bridge",
"ipam": {
"type": "kube-ovn",
"server_socket": "/run/openvswitch/kube-ovn-daemon.sock",
"provider": "eth1.default"
}
}'
---
apiVersion: kubeovn.io/v1
kind: Subnet
metadata:
name: macvlan1
spec:
protocol: IPv4
provider: eth1.default
cidrBlock: 172.17.0.0/16
gateway: 172.17.0.1
excludeIps:
- 172.17.0.0..172.17.0.10
You can create a Network Attachment Definition with any CNI plugin to access the corresponding network.
For details on how to use multi-nic, please refer to Manage Multiple Interface.
Creating a VPC Egress Gateway¶
Create a VPC Egress Gateway resource as shown in the example below:
apiVersion: kubeovn.io/v1
kind: VpcEgressGateway
metadata:
name: gateway1
namespace: default
spec:
vpc: ovn-cluster
replicas: 1
externalSubnet: macvlan1
policies:
- snat: true
subnets:
- ovn-default
The above resource creates a VPC Egress Gateway named gateway1 for VPC ovn-cluster under the default namespace, and all Pods under the ovn-default subnet (10.16.0.0/16) within ovn-cluster VPC will access the external network via the macvlan1 subnet with SNAT applied.
After the creation is complete, check out the VPC Egress Gateway resource:
$ kubectl get veg gateway1
NAME VPC REPLICAS BFD ENABLED EXTERNAL SUBNET PHASE READY AGE
gateway1 ovn-cluster 1 false macvlan1 Completed true 13s
To view more informations:
kubectl get veg gateway1 -o wide
NAME VPC REPLICAS BFD ENABLED EXTERNAL SUBNET PHASE READY INTERNAL IPS EXTERNAL IPS WORKING NODES AGE
gateway1 ovn-cluster 1 false macvlan1 Completed true ["10.16.0.12"] ["172.17.0.11"] ["kube-ovn-worker"] 82s
To view the workload:
$ kubectl get deployment -l ovn.kubernetes.io/vpc-egress-gateway=gateway1
NAME READY UP-TO-DATE AVAILABLE AGE
gateway1 1/1 1 1 4m40s
$ kubectl get pod -l ovn.kubernetes.io/vpc-egress-gateway=gateway1 -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
gateway1-b9f8b4448-76lhm 1/1 Running 0 4m48s 10.16.0.12 kube-ovn-worker <none> <none>
To view IP addresses, routes, and iptables rules in the Pod:
$ kubectl exec gateway1-b9f8b4448-76lhm -c gateway -- ip address show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: net1@if13: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 62:d8:71:90:7b:86 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 172.17.0.11/16 brd 172.17.255.255 scope global net1
valid_lft forever preferred_lft forever
inet6 fe80::60d8:71ff:fe90:7b86/64 scope link
valid_lft forever preferred_lft forever
17: eth0@if18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1400 qdisc noqueue state UP group default
link/ether 36:7c:6b:c7:82:6b brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 10.16.0.12/16 brd 10.16.255.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::347c:6bff:fec7:826b/64 scope link
valid_lft forever preferred_lft forever
$ kubectl exec gateway1-b9f8b4448-76lhm -c gateway -- ip route show
default via 172.17.0.1 dev net1
10.16.0.0/16 dev eth0 proto kernel scope link src 10.16.0.12
172.17.0.0/16 dev net1 proto kernel scope link src 172.17.0.11
$ kubectl exec gateway1-b9f8b4448-76lhm -c gateway -- iptables -t nat -S
-P PREROUTING ACCEPT
-P INPUT ACCEPT
-P OUTPUT ACCEPT
-P POSTROUTING ACCEPT
-A POSTROUTING -s 10.16.0.0/16 -j MASQUERADE --random-fully
Capture packets in the Gateway Pod to verify network traffic:
$ kubectl exec -ti gateway1-b9f8b4448-76lhm -c gateway -- bash
nobody@gateway1-b9f8b4448-76lhm:/kube-ovn$ tcpdump -i any -nnve icmp and host 172.17.0.1
tcpdump: data link type LINUX_SLL2
tcpdump: listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
06:50:58.936528 eth0 In ifindex 17 92:26:b8:9e:f2:1c ethertype IPv4 (0x0800), length 104: (tos 0x0, ttl 63, id 30481, offset 0, flags [DF], proto ICMP (1), length 84)
10.16.0.9 > 172.17.0.1: ICMP echo request, id 37989, seq 0, length 64
06:50:58.936574 net1 Out ifindex 2 62:d8:71:90:7b:86 ethertype IPv4 (0x0800), length 104: (tos 0x0, ttl 62, id 30481, offset 0, flags [DF], proto ICMP (1), length 84)
172.17.0.11 > 172.17.0.1: ICMP echo request, id 39449, seq 0, length 64
06:50:58.936613 net1 In ifindex 2 02:42:39:79:7f:08 ethertype IPv4 (0x0800), length 104: (tos 0x0, ttl 64, id 26701, offset 0, flags [none], proto ICMP (1), length 84)
172.17.0.1 > 172.17.0.11: ICMP echo reply, id 39449, seq 0, length 64
06:50:58.936621 eth0 Out ifindex 17 36:7c:6b:c7:82:6b ethertype IPv4 (0x0800), length 104: (tos 0x0, ttl 63, id 26701, offset 0, flags [none], proto ICMP (1), length 84)
172.17.0.1 > 10.16.0.9: ICMP echo reply, id 37989, seq 0, length 64
Routing policies (static routes for custom VPCs) are automatically created on the OVN Logical Router:
$ kubectl ko nbctl lr-policy-list ovn-cluster
Routing Policies
31000 ip4.dst == 10.16.0.0/16 allow
31000 ip4.dst == 100.64.0.0/16 allow
30000 ip4.dst == 172.18.0.2 reroute 100.64.0.3
30000 ip4.dst == 172.18.0.3 reroute 100.64.0.2
30000 ip4.dst == 172.18.0.4 reroute 100.64.0.4
29100 ip4.src == 10.16.0.0/16 reroute 10.16.0.12
29000 ip4.src == $ovn.default.kube.ovn.control.plane_ip4 reroute 100.64.0.2
29000 ip4.src == $ovn.default.kube.ovn.worker2_ip4 reroute 100.64.0.4
29000 ip4.src == $ovn.default.kube.ovn.worker_ip4 reroute 100.64.0.3
If you need to enable load balancing, modify .spec.replicas as shown in the following example:
$ kubectl scale veg gateway1 --replicas=2
vpcegressgateway.kubeovn.io/gateway1 scaled
$ kubectl get veg gateway1
NAME VPC REPLICAS BFD ENABLED EXTERNAL SUBNET PHASE READY AGE
gateway1 ovn-cluster 2 false macvlan Completed true 39m
$ kubectl get pod -l ovn.kubernetes.io/vpc-egress-gateway=gateway1 -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
gateway1-b9f8b4448-76lhm 1/1 Running 0 40m 10.16.0.12 kube-ovn-worker <none> <none>
gateway1-b9f8b4448-zd4dl 1/1 Running 0 64s 10.16.0.13 kube-ovn-worker2 <none> <none>
$ kubectl ko nbctl lr-policy-list ovn-cluster
Routing Policies
31000 ip4.dst == 10.16.0.0/16 allow
31000 ip4.dst == 100.64.0.0/16 allow
30000 ip4.dst == 172.18.0.2 reroute 100.64.0.3
30000 ip4.dst == 172.18.0.3 reroute 100.64.0.2
30000 ip4.dst == 172.18.0.4 reroute 100.64.0.4
29100 ip4.src == 10.16.0.0/16 reroute 10.16.0.12, 10.16.0.13
29000 ip4.src == $ovn.default.kube.ovn.control.plane_ip4 reroute 100.64.0.2
29000 ip4.src == $ovn.default.kube.ovn.worker2_ip4 reroute 100.64.0.4
29000 ip4.src == $ovn.default.kube.ovn.worker_ip4 reroute 100.64.0.3
Specifying Egress Gateway IP and Deployment Nodes¶
You can use the externalIPs and nodeSelector fields to specify the Egress IPs used by Egress Gateway Pods and the nodes they are deployed on:
apiVersion: kubeovn.io/v1
kind: VpcEgressGateway
metadata:
name: gateway1
namespace: default
spec:
vpc: ovn-cluster
replicas: 2
externalSubnet: macvlan1
policies:
- snat: true
subnets:
- ovn-default
externalIPs:
- 172.17.0.10
- 172.17.0.11
nodeSelector:
- matchLabels:
kubernetes.io/hostname: kube-ovn-worker
Enabling BFD-based High Availability¶
BFD-based high availability relies on the VPC BFD LRP function, so you need to modify the VPC resource to enable BFD Port. Here is an example:
apiVersion: kubeovn.io/v1
kind: Vpc
metadata:
name: vpc1
spec:
bfdPort:
enabled: true
ip: 10.255.255.255
---
apiVersion: kubeovn.io/v1
kind: Subnet
metadata:
name: subnet1
spec:
vpc: vpc1
protocol: IPv4
cidrBlock: 192.168.0.0/24
After the BFD Port is enabled, an LRP dedicated to BFD is automatically created on the corresponding OVN LR:
$ kubectl ko nbctl show vpc1
router 0c1d1e8f-4c86-4d96-88b2-c4171c7ff824 (vpc1)
port bfd@vpc1
mac: "8e:51:4b:16:3c:90"
networks: ["10.255.255.255"]
port vpc1-subnet1
mac: "de:c9:5c:38:7a:61"
networks: ["192.168.0.1/24"]
After that, set .spec.bfd.enabled to true in VPC Egress Gateway. An example is shown below:
apiVersion: kubeovn.io/v1
kind: VpcEgressGateway
metadata:
name: gateway2
namespace: default
spec:
vpc: vpc1
replicas: 2
internalSubnet: subnet1
externalSubnet: macvlan
bfd:
enabled: true
policies:
- snat: true
ipBlocks:
- 192.168.0.0/24
To view VPC Egress Gateway information:
$ kubectl get veg gateway2 -o wide
NAME VPC REPLICAS BFD ENABLED EXTERNAL SUBNET PHASE READY INTERNAL IPS EXTERNAL IPS WORKING NODES AGE
gateway2 vpc1 2 true macvlan Completed true ["192.168.0.2","192.168.0.3"] ["172.17.0.13","172.17.0.14"] ["kube-ovn-worker","kube-ovn-worker2"] 58s
$ kubectl get pod -l ovn.kubernetes.io/vpc-egress-gateway=gateway2 -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
gateway2-fcc6b8b87-8lgvx 1/1 Running 0 2m18s 192.168.0.3 kube-ovn-worker2 <none> <none>
gateway2-fcc6b8b87-wmww6 1/1 Running 0 2m18s 192.168.0.2 kube-ovn-worker <none> <none>
$ kubectl ko nbctl lr-route-list vpc1
IPv4 Routes
Route Table <main>:
192.168.0.0/24 192.168.0.2 src-ip ecmp ecmp-symmetric-reply bfd
192.168.0.0/24 192.168.0.3 src-ip ecmp ecmp-symmetric-reply bfd
$ kubectl ko nbctl list bfd
_uuid : 223ede10-9169-4c7d-9524-a546e24bfab5
detect_mult : 3
dst_ip : "192.168.0.2"
external_ids : {af="4", vendor=kube-ovn, vpc-egress-gateway="default/gateway2"}
logical_port : "bfd@vpc1"
min_rx : 1000
min_tx : 1000
options : {}
status : up
_uuid : b050c75e-2462-470b-b89c-7bd38889b758
detect_mult : 3
dst_ip : "192.168.0.3"
external_ids : {af="4", vendor=kube-ovn, vpc-egress-gateway="default/gateway2"}
logical_port : "bfd@vpc1"
min_rx : 1000
min_tx : 1000
options : {}
status : up
To view BFD connections:
$ kubectl exec gateway2-fcc6b8b87-8lgvx -c bfdd -- bfdd-control status
There are 1 sessions:
Session 1
id=1 local=192.168.0.3 (p) remote=10.255.255.255 state=Up
$ kubectl exec gateway2-fcc6b8b87-wmww6 -c bfdd -- bfdd-control status
There are 1 sessions:
Session 1
id=1 local=192.168.0.2 (p) remote=10.255.255.255 state=Up
Configuration Parameters¶
VPC BFD Port¶
| Fields | Type | Optional | Default Value | Description | Example |
|---|---|---|---|---|---|
enabled | boolean | Yes | false | Whether to enable the BFD Port. | true |
ip | string | No | - | The IP address used by the BFD Port. Must NOT conflict with other addresses. IPv4, IPv6 and dual-stack are supported. | 169.255.255.255 / fdff::1 / 169.255.255.255,fdff::1 |
nodeSelector | object | Yes | - | Label selector used to select nodes that carries the BFD Port work. the BFD Port binds an OVN HA Chassis Group of selected nodes and works in Active/Backup mode. If this field is not specified, Kube-OVN automatically selects up to three nodes. You can view all OVN HA Chassis Group resources by executing kubectl ko nbctl list ha_chassis_group. | - |
nodeSelector.matchLabels | dict/map | Yes | - | A map of {key,value} pairs. | - |
nodeSelector.matchExpressions | object array | Yes | - | A list of label selector requirements. The requirements are ANDed. | - |
VPC Egress Gateway¶
Spec:
| Fields | Type | Optional | Default Value | Description | Example |
|---|---|---|---|---|---|
vpc | string | Yes | Name of the default VPC (ovn-cluster) | VPC name. | vpc1 |
replicas | integer/int32 | Yes | 1 | Replicas. | 2 |
prefix | string | Yes | - | Prefix of the workload deployment name. This field is immutable. | veg- |
image | string | Yes | - | The image used by the workload deployment. | docker.io/kubeovn/kube-ovn:v1.14.0-debug |
internalSubnet | string | Yes | Name of the default subnet within the VPC. | Name of the subnet used to access the VPC network. | subnet1 |
externalSubnet | string | No | - | Name of the subnet used to access the external network. | ext1 |
internalIPs | string array | Yes | - | IP addresses used for accessing the VPC network. IPv4, IPv6 and dual-stack are supported. The number of IPs specified must NOT be less than replicas. It is recommended to set the number to <replicas> + 1 to avoid extreme cases where the Pod is not created properly. | 10.16.0.101 / fd00::11 / 10.16.0.101,fd00::11 |
externalIPs | string array | Yes | - | IP addresses used for accessing the external network. IPv4, IPv6 and dual-stack are supported. The number of IPs specified must NOT be less than replicas. It is recommended to set the number to <replicas> + 1 to avoid extreme cases where the Pod is not created properly. | 10.16.0.101 / fd00::11 / 10.16.0.101,fd00::11 |
bfd | object | Yes | - | BFD Configuration. | - |
policies | object array | Yes | - | Egress policies. Configurable when selectors is configured. | - |
selectors | object array | Yes | - | Configure Egress policies by namespace selectors and Pod selectors. SNAT/MASQUERADE will be applied to the matched Pods. Configurable when policies is configured. | - |
nodeSelector | object array | Yes | - | Node selector applied to the workload. The workload (Deployment/Pod) will run on the selected nodes. | - |
trafficPolicy | string | Yes | Cluster | Available values: Cluster/Local. Effective only when BFD is enabled. When set to Local, Egress traffic will be redirected to the VPC Egress Gateway instance running on the same node if available. If the instance is down, Egress traffic will be redirected to other instances. | Local |
BFD Configuration:
| Fields | Type | Optional | Default Value | Description | Example |
|---|---|---|---|---|---|
enabled | boolean | Yes | false | Whether to enable BFD. | true |
minRX | integer/int32 | Yes | 1000 | BFD minRX in milliseconds. | 500 |
minTX | integer/int32 | Yes | 1000 | BFD minTX in milliseconds. | 500 |
multiplier | integer/int32 | Yes | 3 | BFD multiplier. | 1 |
Egress Policies:
| Fields | Type | Optional | Default Value | Description | Example |
|---|---|---|---|---|---|
snat | boolean | Yes | false | Whether to enable SNAT/MASQUERADE. | true |
ipBlocks | string array | Yes | - | IP range segments applied to this Gateway. Both IPv4 and IPv6 are supported. | 192.168.0.1 / 192.168.0.0/24 |
subnets | string array | Yes | - | The VPC subnet name applied to this Gateway. IPv4, IPv6 and dual-stack subnets are supported. | subnet1 |
Selectors:
| Fields | Type | Optional | Default Value | Description | Example |
|---|---|---|---|---|---|
namespaceSelector | object | Yes | - | Namespace selector. An empty label selector matches all namespaces. | - |
namespaceSelector.matchLabels | dict/map | Yes | - | A map of {key,value} pairs. | - |
namespaceSelector.matchExpressions | object array | Yes | - | A list of label selector requirements. The requirements are ANDed. | - |
podSelector | object | Yes | - | Pod selector. An empty label selector matches all Pods. | - |
podSelector.matchLabels | dict/map | Yes | - | A map of {key,value} pairs. | - |
podSelector.matchExpressions | object array | Yes | - | A list of label selector requirements. The requirements are ANDed. | - |
Node selector:
| Fields | Type | Optional | Default Value | Description | Example |
|---|---|---|---|---|---|
matchLabels | dict/map | Yes | - | A map of {key,value} pairs. | - |
matchExpressions | object array | Yes | - | A list of label selector requirements. The requirements are ANDed. | - |
matchFields | object array | Yes | - | A list of field selector requirements. The requirements are ANDed. | - |
Status:
| Fields | Type | Description | Example |
|---|---|---|---|
ready | boolean | Whether the gateway is ready. | true |
phase | string | The gateway processing phase. | Pending / Processing / Completed |
internalIPs | string array | IP addresses used to access the VPC network. | - |
externalIPs | string array | IP addresses used to access the external network. | - |
workload | object | Workload information. | - |
workload.apiVersion | string | Workload API version. | apps/v1 |
workload.kind | string | Workload kind. | Deployment |
workload.name | string | Workload name. | gateway1 |
workload.nodes | string array | Names of the nodes where the workload resides. | - |
conditions | object array | - | - |