The best way to get started is to deploy Kubernetes with Kube-router is with a cluster installer.
Please see the steps to deploy Kubernetes cluster with Kube-router using Kops
Please see the steps to deploy Kubernetes cluster with Kube-router using bootkube
Please see the steps to deploy Kubernetes cluster with Kube-router using Kubeadm
k0s by default uses kube-router as a CNI option. Please see the steps to deploy Kubernetes cluster with Kube-router using k0s
Please see the steps to deploy kube-router on manually installed clusters
When running in an AWS environment that requires an explicit proxy you need to inject the proxy server as a environment variable in your kube-router deployment
Example:
env:
- name: HTTP_PROXY
value: "http://proxy.example.com:80"
Depending on what functionality of kube-router you want to use, multiple deployment options are possible. You can use the flags --run-firewall, --run-router, --run-service-proxy to selectively enable only required functionality of kube-router.
Also you can choose to run kube-router as agent running on each cluster node. Alternativley you can run kube-router as pod on each node through daemonset.
Usage of kube-router:
--advertise-cluster-ip Add Cluster IP of the service to the RIB so that it gets advertises to the BGP peers.
--advertise-external-ip Add External IP of service to the RIB so that it gets advertised to the BGP peers.
--advertise-loadbalancer-ip Add LoadbBalancer IP of service status as set by the LB provider to the RIB so that it gets advertised to the BGP peers.
--advertise-pod-cidr Add Node's POD cidr to the RIB so that it gets advertised to the BGP peers. (default true)
--auto-mtu Auto detect and set the largest possible MTU for kube-bridge and pod interfaces (also accounts for IPIP overlay network when enabled). (default true)
--bgp-graceful-restart Enables the BGP Graceful Restart capability so that routes are preserved on unexpected restarts
--bgp-graceful-restart-deferral-time duration BGP Graceful restart deferral time according to RFC4724 4.1, maximum 18h. (default 6m0s)
--bgp-graceful-restart-time duration BGP Graceful restart time according to RFC4724 3, maximum 4095s. (default 1m30s)
--bgp-holdtime duration This parameter is mainly used to modify the holdtime declared to BGP peer. When Kube-router goes down abnormally, the local saving time of BGP route will be affected. Holdtime must be in the range 3s to 18h12m16s. (default 1m30s)
--bgp-port uint32 The port open for incoming BGP connections and to use for connecting with other BGP peers. (default 179)
--cache-sync-timeout duration The timeout for cache synchronization (e.g. '5s', '1m'). Must be greater than 0. (default 1m0s)
--cleanup-config Cleanup iptables rules, ipvs, ipset configuration and exit.
--cluster-asn uint ASN number under which cluster nodes will run iBGP.
--disable-source-dest-check Disable the source-dest-check attribute for AWS EC2 instances. When this option is false, it must be set some other way. (default true)
--enable-cni Enable CNI plugin. Disable if you want to use kube-router features alongside another CNI plugin. (default true)
--enable-ibgp Enables peering with nodes with the same ASN, if disabled will only peer with external BGP peers (default true)
--enable-overlay When enable-overlay is set to true, IP-in-IP tunneling is used for pod-to-pod networking across nodes in different subnets. When set to false no tunneling is used and routing infrastructure is expected to route traffic for pod-to-pod networking across nodes in different subnets (default true)
--enable-pod-egress SNAT traffic from Pods to destinations outside the cluster. (default true)
--enable-pprof Enables pprof for debugging performance and memory leak issues.
--excluded-cidrs strings Excluded CIDRs are used to exclude IPVS rules from deletion.
--hairpin-mode Add iptables rules for every Service Endpoint to support hairpin traffic.
--health-port uint16 Health check port, 0 = Disabled (default 20244)
-h, --help Print usage information.
--hostname-override string Overrides the NodeName of the node. Set this if kube-router is unable to determine your NodeName automatically.
--injected-routes-sync-period duration The delay between route table synchronizations (e.g. '5s', '1m', '2h22m'). Must be greater than 0. (default 1m0s)
--iptables-sync-period duration The delay between iptables rule synchronizations (e.g. '5s', '1m'). Must be greater than 0. (default 5m0s)
--ipvs-graceful-period duration The graceful period before removing destinations from IPVS services (e.g. '5s', '1m', '2h22m'). Must be greater than 0. (default 30s)
--ipvs-graceful-termination Enables the experimental IPVS graceful terminaton capability
--ipvs-permit-all Enables rule to accept all incoming traffic to service VIP's on the node. (default true)
--ipvs-sync-period duration The delay between ipvs config synchronizations (e.g. '5s', '1m', '2h22m'). Must be greater than 0. (default 5m0s)
--kubeconfig string Path to kubeconfig file with authorization information (the master location is set by the master flag).
--masquerade-all SNAT all traffic to cluster IP/node port.
--master string The address of the Kubernetes API server (overrides any value in kubeconfig).
--metrics-path string Prometheus metrics path (default "/metrics")
--metrics-port uint16 Prometheus metrics port, (Default 0, Disabled)
--nodeport-bindon-all-ip For service of NodePort type create IPVS service that listens on all IP's of the node.
--nodes-full-mesh Each node in the cluster will setup BGP peering with rest of the nodes. (default true)
--overlay-type string Possible values: subnet,full - When set to "subnet", the default, default "--enable-overlay=true" behavior is used. When set to "full", it changes "--enable-overlay=true" default behavior so that IP-in-IP tunneling is used for pod-to-pod networking across nodes regardless of the subnet the nodes are in. (default "subnet")
--override-nexthop Override the next-hop in bgp routes sent to peers with the local ip.
--peer-router-asns uints ASN numbers of the BGP peer to which cluster nodes will advertise cluster ip and node's pod cidr. (default [])
--peer-router-ips ipSlice The ip address of the external router to which all nodes will peer and advertise the cluster ip and pod cidr's. (default [])
--peer-router-multihop-ttl uint8 Enable eBGP multihop supports -- sets multihop-ttl. (Relevant only if ttl >= 2)
--peer-router-passwords strings Password for authenticating against the BGP peer defined with "--peer-router-ips".
--peer-router-passwords-file string Path to file containing password for authenticating against the BGP peer defined with "--peer-router-ips". --peer-router-passwords will be preferred if both are set.
--peer-router-ports uints The remote port of the external BGP to which all nodes will peer. If not set, default BGP port (179) will be used. (default [])
--router-id string BGP router-id. Must be specified in a ipv6 only cluster.
--routes-sync-period duration The delay between route updates and advertisements (e.g. '5s', '1m', '2h22m'). Must be greater than 0. (default 5m0s)
--run-firewall Enables Network Policy -- sets up iptables to provide ingress firewall for pods. (default true)
--run-router Enables Pod Networking -- Advertises and learns the routes to Pods via iBGP. (default true)
--run-service-proxy Enables Service Proxy -- sets up IPVS for Kubernetes Services. (default true)
--runtime-endpoint string Path to CRI compatible container runtime socket (used for DSR mode). Currently known working with containerd.
--service-cluster-ip-range string CIDR value from which service cluster IPs are assigned. Default: 10.96.0.0/12 (default "10.96.0.0/12")
--service-external-ip-range strings Specify external IP CIDRs that are used for inter-cluster communication (can be specified multiple times)
--service-node-port-range string NodePort range specified with either a hyphen or colon (default "30000-32767")
-v, --v string log level for V logs (default "0")
-V, --version Print version information.
-
Kube-router need to access kubernetes API server to get information on pods, services, endpoints, network policies etc. The very minimum information it requires is the details on where to access the kubernetes API server. This information can be passed as
kube-router --master=http://192.168.1.99:8080/orkube-router --kubeconfig=<path to kubeconfig file>. -
If you run kube-router as agent on the node, ipset package must be installed on each of the nodes (when run as daemonset, container image is prepackaged with ipset)
-
If you choose to use kube-router for pod-to-pod network connectivity then Kubernetes controller manager need to be configured to allocate pod CIDRs by passing
--allocate-node-cidrs=trueflag and providing acluster-cidr(i.e. by passing --cluster-cidr=10.1.0.0/16 for e.g.) -
If you choose to run kube-router as daemonset in Kubernetes version below v1.15, both kube-apiserver and kubelet must be run with
--allow-privileged=trueoption. In later Kubernetes versions, only kube-apiserver must be run with--allow-privileged=trueoption and if PodSecurityPolicy admission controller is enabled, you should create PodSecurityPolicy, allowing privileged kube-router pods.- Additionally, when run in daemonset mode, it is highly recommended that you keep netfilter related userspace host tooling like
iptables,ipset, andipvsadmin sync with the versions that are distributed by Alpine inside the kube-router container. This will help avoid conflicts that can potentially arise when both the host's userspace and kube-router's userspace tooling modifies netfilter kernel definitions. See: cloudnativelabs#1370 for more information.
- Additionally, when run in daemonset mode, it is highly recommended that you keep netfilter related userspace host tooling like
-
If you choose to use kube-router for pod-to-pod network connecitvity then Kubernetes cluster must be configured to use CNI network plugins. On each node CNI conf file is expected to be present as /etc/cni/net.d/10-kuberouter.conf .
bridgeCNI plugin andhost-localfor IPAM should be used. A sample conf file that can be downloaded aswget -O /etc/cni/net.d/10-kuberouter.conf https://raw.githubusercontent.com/cloudnativelabs/kube-router/master/cni/10-kuberouter.conf
This is quickest way to deploy kube-router in Kubernetes v1.8+ (dont forget to ensure the requirements above). Just run:
kubectl apply -f https://raw.githubusercontent.com/cloudnativelabs/kube-router/master/daemonset/kube-router-all-service-daemonset.yaml
Above will run kube-router as pod on each node automatically. You can change the arguments in the daemonset definition as required to suit your needs. Some samples can be found at https://github.com/cloudnativelabs/kube-router/tree/master/daemonset with different argument to select set of the services kube-router should run.
You can choose to run kube-router as agent runnng on each node. For e.g if you just want kube-router to provide ingress firewall for the pods then you can start kube-router as
kube-router --master=http://192.168.1.99:8080/ --run-firewall=true --run-service-proxy=false --run-router=false
Please delete kube-router daemonset and then clean up all the configurations done (to ipvs, iptables, ipset, ip routes etc) by kube-router on the node by running below command.
docker run --privileged --net=host cloudnativelabs/kube-router --cleanup-config
If you have a kube-proxy in use, and want to try kube-router just for service proxy you can do
kube-proxy --cleanup-iptables
followed by
kube-router --master=http://192.168.1.99:8080/ --run-service-proxy=true --run-firewall=false --run-router=false
and if you want to move back to kube-proxy then clean up config done by kube-router by running
kube-router --cleanup-config
and run kube-proxy with the configuration you have.
kube-router can advertise Cluster, External and LoadBalancer IPs to BGP peers. It does this by:
- locally adding the advertised IPs to the nodes'
kube-dummy-ifnetwork interface - advertising the IPs to its BGP peers
To set the default for all services use the --advertise-cluster-ip,
--advertise-external-ip and --advertise-loadbalancer-ip flags.
To selectively enable or disable this feature per-service use the
kube-router.io/service.advertise.clusterip, kube-router.io/service.advertise.externalip
and kube-router.io/service.advertise.loadbalancerip annotations.
e.g.:
$ kubectl annotate service my-advertised-service "kube-router.io/service.advertise.clusterip=true"
$ kubectl annotate service my-advertised-service "kube-router.io/service.advertise.externalip=true"
$ kubectl annotate service my-advertised-service "kube-router.io/service.advertise.loadbalancerip=true"
$ kubectl annotate service my-non-advertised-service "kube-router.io/service.advertise.clusterip=false"
$ kubectl annotate service my-non-advertised-service "kube-router.io/service.advertise.externalip=false"
$ kubectl annotate service my-non-advertised-service "kube-router.io/service.advertise.loadbalancerip=false"
By combining the flags with the per-service annotations you can choose either a opt-in or opt-out strategy for advertising IPs.
Advertising LoadBalancer IPs works by inspecting the services
status.loadBalancer.ingress IPs that are set by external LoadBalancers like
for example MetalLb. This has been successfully tested together with
MetalLB in ARP mode.
Communication from a Pod that is behind a Service to its own ClusterIP:Port is
not supported by default. However, It can be enabled per-service by adding the
kube-router.io/service.hairpin= annotation, or for all Services in a cluster by
passing the flag --hairpin-mode=true to kube-router.
Additionally, the hairpin_mode sysctl option must be set to 1 for all veth
interfaces on each node. This can be done by adding the "hairpinMode": true
option to your CNI configuration and rebooting all cluster nodes if they are
already running kubernetes.
Hairpin traffic will be seen by the pod it originated from as coming from the Service ClusterIP if it is logging the source IP.
10-kuberouter.conf
{
"name":"mynet",
"type":"bridge",
"bridge":"kube-bridge",
"isDefaultGateway":true,
"hairpinMode":true,
"ipam": {
"type":"host-local"
}
}To enable hairpin traffic for Service my-service:
kubectl annotate service my-service "kube-router.io/service.hairpin="
If you want to also hairpin externalIPs declared for Service my-service (note, you must also either enable global hairpin or service hairpin (see above ^^^) for this to have an effect):
kubectl annotate service my-service "kube-router.io/service.hairpin.externalips="
By default, as traffic ingresses into the cluster, kube-router will source nat the traffic to ensure symmetric routing if it needs to proxy that traffic to ensure it gets to a node that has a service pod that is capable of servicing the traffic. This has a potential to cause issues when network policies are applied to that service since now the traffic will appear to be coming from a node in your cluster instead of the traffic originator.
This is an issue that is common to all proxy's and all Kubernetes service proxies in general. You can read more information about this issue here: https://kubernetes.io/docs/tutorials/services/source-ip/#source-ip-for-services-with-type-nodeport
In addition to the fix mentioned in the linked upstream documentation (using service.spec.externalTrafficPolicy), kube-router also provides DSR, which by its nature preserves the source IP, to solve this problem. For more information see the section above.
Kube-router uses LVS for service proxy. LVS support rich set of scheduling alogirthms. You can annotate
the service to choose one of the scheduling alogirthms. When a service is not annotated round-robin scheduler is selected by default
For least connection scheduling use:
kubectl annotate service my-service "kube-router.io/service.scheduler=lc"
For round-robin scheduling use:
kubectl annotate service my-service "kube-router.io/service.scheduler=rr"
For source hashing scheduling use:
kubectl annotate service my-service "kube-router.io/service.scheduler=sh"
For destination hashing scheduling use:
kubectl annotate service my-service "kube-router.io/service.scheduler=dh"
If you would like to use HostPort functionality below changes are required in the manifest.
- By default kube-router assumes CNI conf file to be
/etc/cni/net.d/10-kuberouter.conf. Add an environment variableKUBE_ROUTER_CNI_CONF_FILEto kube-router manifest and set it to/etc/cni/net.d/10-kuberouter.conflist - Modify
kube-router-cfgConfigMap with CNI config that supportsportmapas additional plug-in
{
"cniVersion":"0.3.0",
"name":"mynet",
"plugins":[
{
"name":"kubernetes",
"type":"bridge",
"bridge":"kube-bridge",
"isDefaultGateway":true,
"ipam":{
"type":"host-local"
}
},
{
"type":"portmap",
"capabilities":{
"snat":true,
"portMappings":true
}
}
]
}
- Update init container command to create
/etc/cni/net.d/10-kuberouter.conflistfile - Restart the container runtime
For an e.g manifest please look at manifest with necessary changes required for HostPort functionality.
As of 0.2.6 we support experimental graceful termination of IPVS destinations. When possible the pods's TerminationGracePeriodSeconds is used, if it cannot be retrived for some reason
the fallback period is 30 seconds and can be adjusted with --ipvs-graceful-period cli-opt
graceful termination works in such a way that when kube-router receives a delete endpoint notification for a service it's weight is adjusted to 0 before getting deleted after he termination grace period has passed or the Active & Inactive connections goes down to 0.
The maximum transmission unit (MTU) determines the largest packet size that can be transmitted through your network. MTU for the pod interfaces should be set appropriately to prevent fragmentation and packet drops thereby achieving maximum performance. If auto-mtu is set to true (auto-mtu is set to true by default as of kube-router 1.1), kube-router will determine right MTU for both kube-bridge and pod interfaces. If you set auto-mtu to false kube-router will not attempt to configure MTU. However you can choose the right MTU and set in the cni-conf.json section of the 10-kuberouter.conflist in the kube-router daemonsets. For e.g.
cni-conf.json: |
{
"cniVersion":"0.3.0",
"name":"mynet",
"plugins":[
{
"name":"kubernetes",
"type":"bridge",
"mtu": 1400,
"bridge":"kube-bridge",
"isDefaultGateway":true,
"ipam":{
"type":"host-local"
}
}
]
}
If you set MTU yourself via the CNI config, you'll also need to set MTU of kube-bridge manually to the right value to avoid packet fragmentation in case of existing nodes on which kube-bridge is already created. On node reboot or in case of new nodes joining the cluster both the pod's interface and kube-bridge will be setup with specified MTU value.