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typhoon/docs/topics/hardware.md
Dalton Hubble 6f958d7577 Replace kube-dns with CoreDNS
* Add system:coredns ClusterRole and binding
* Annotate CoreDNS for Prometheus metrics scraping
* Remove kube-dns deployment, service, & service account
* https://github.com/poseidon/terraform-render-bootkube/pull/71
* https://kubernetes.io/blog/2018/06/27/kubernetes-1.11-release-announcement/
2018-07-01 22:55:01 -07:00

4.9 KiB

Hardware

Typhoon ensures certain networking hardware integrates well with bare-metal Kubernetes.

Ubiquiti

Ubiquiti EdgeRouters work well with bare-metal Kubernetes clusters. Knowledge about how to setup an EdgeRouter and use the CLI is required.

PXE

Ubiquiti EdgeRouters can provide a PXE-enabled network boot environment for client machines.

ISC DHCP

Add a subnet parameter to the LAN DHCP server to include an ISC DHCP config file.

configure
show service dhcp-server shared-network-name NAME subnet SUBNET
set service dhcp-server shared-network-name NAME subnet SUBNET subnet-parameters "include "/config/scripts/ipxe.conf";"
commit-confirm

Switch to root (i.e. sudo -i) and write the ISC DHCP config /config/scripts/ipxe.conf. iPXE client machines will chainload to matchbox.example.com, while non-iPXE clients will chainload to undionly.kpxe (requires TFTP to be enabled).

allow bootp;
allow booting;
next-server ADD_ROUTER_IP_HERE;

if exists user-class and option user-class = "iPXE" {
  filename "http://matchbox.example.com/boot.ipxe";
} else {
  filename "undionly.kpxe";
}

TFTP

Use dnsmasq as a TFTP server to serve undionly.kpxe.

sudo -i
mkdir /var/lib/tftpboot
cd /var/lib/tftpboot
curl http://boot.ipxe.org/undionly.kpxe -o undionly.kpxe

Add dnsmasq command line options to enable the TFTP file server.

configure
show service dns forwarding
set service dns forwarding options enable-tftp
set service dns forwarding options tftp-root=/var/lib/tftpboot
commit-confirm

!!! warning After firmware upgrades, the /var/lib/tftpboot directory will not exist and dnsmasq will not start properly. Repeat this process following an upgrade.

DHCP

Assign static IPs to clients with known MAC addresses. This is called a static mapping by EdgeOS. Configure the router with the commands based on region inventory.

configure
show service dhcp-server shared-network
set service dhcp-server shared-network-name LAN subnet SUBNET static-mapping NAME mac-address MACADDR
set service dhcp-server shared-network-name LAN subnet SUBNET static-mapping NAME ip-address 10.0.0.20

DNS

Assign DNS A records to nodes as options to dnsmasq.

configure
set service dns forwarding options host-record=node.example.com,10.0.0.20

Restart dnsmasq.

sudo /etc/init.d/dnsmasq restart

Configure queries for *.svc.cluster.local to be forwarded to the Kubernetes coredns service IP to allow hosts to resolve cluster-local Kubernetes names.

configure
show service dns forwarding
set service dns forwarding options server=/svc.cluster.local/10.3.0.10
commit-confirm

Kubernetes Services

Add static routes for the Kubernetes IPv4 service range to Kubernetes node(s) so hosts can route to Kubernetes services (default: 10.3.0.0/16).

configure
show protocols static route
set protocols static route 10.3.0.0/16 next-hop NODE_IP
...
commit-confirm

Port Forwarding

Expose the Ingress Controller by adding port-forward rules that DNAT a port on the router's WAN interface to an internal IP and port. By convention, a public Ingress controller is assigned a fixed service IP (e.g. 10.3.0.12).

configure
set port-forward wan-interface eth0
set port-forward lan-interface eth1
set port-forward auto-firewall enable
set port-forward hairpin-nat enable
set port-forward rule 1 description 'ingress http'
set port-forward rule 1 forward-to address 10.3.0.12
set port-forward rule 1 forward-to port 80
set port-forward rule 1 original-port 80
set port-forward rule 1 protocol tcp_udp
set port-forward rule 2 description 'ingress https'
set port-forward rule 2 forward-to address 10.3.0.12
set port-forward rule 2 forward-to port 443
set port-forward rule 2 original-port 443
set port-forward rule 2 protocol tcp_udp
commit-confirm

Web UI

The web UI is often accessible from the LAN on ports 80/443 by default. Edit the ports to 8080 and 4443 to avoid a conflict.

configure
show service gui
set service gui http-port 8080
set service gui https-port 4443
commit-confirm

BGP

Add the EdgeRouter as a global BGP peer for nodes in a Kubernetes cluster (requires Calico). Neighbors will exchange podCIDR routes and individual pods will become routable on the LAN.

Configure node(s) as BGP neighbors.

show protocols bgp 1
set protocols bgp 1 parameters router-id LAN_IP
set protocols bgp 1 neighbor NODE1_IP remote-as 64512
set protocols bgp 1 neighbor NODE2_IP remote-as 64512
set protocols bgp 1 neighbor NODE3_IP remote-as 64512

View the neighbors and exchanged routes.

show ip bgp neighbors
show ip route bgp

Be sure to register the peer by creating a Calico BGPPeer CRD with kubectl apply.

apiVersion: crd.projectcalico.org/v1
kind: BGPPeer
metadata:
  name: NAME
spec:
  peerIP: LAN_IP
  asNumber: 64512