236 lines
7.4 KiB
Markdown
236 lines
7.4 KiB
Markdown
## IPv6 only kubernetes clusters
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This project is testing, deploying and using IPv6 only k8s clusters.
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## Docs
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* [Setting up the cluster with calico](v3-calico/README.md)
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* [Bootstrapping Rook](rook/README.md)
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## Working
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* networking (calico)
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* ceph with rook (cephfs, rbd)
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## Not (yet) working or tested
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* virtualisation (VMs, kubevirt)
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* letsencrypt
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* network policies
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* prometheus in the cluster
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* argocd (?) for CI and upgrades
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* Maybe LoadBalancer support (our ClusterIP already does that though)
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* (Other) DNS entrys for services
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## Cluster setup
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* Calico CNI with BGP peering to our upstream infrastructure
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* Rook for RBD and CephFS support
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The following steps are a full walk through on setting up the
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IPv6 only kubernetes cluster "c2.k8s.ooo".
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### Initialise the master with kubeadm
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We are using a custom kubeadm.conf to
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* configure the cgroupdriver
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* configure the IP addresses
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* configure the DNS domain (c2.k8s.ooo)
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```
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kubeadm init --config k8s/c2/kubeadm.yaml
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```
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### Adding worker nodes
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```
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kubeadm join [2a0a:e5c0:13:0:225:b3ff:fe20:38cc]:6443 --token cfrita.. \
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--discovery-token-ca-cert-hash sha256:...
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```
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Verifying that all nodes joined:
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```
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% kubectl get nodes
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NAME STATUS ROLES AGE VERSION
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server47 Ready control-plane,master 2m25s v1.21.1
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server48 Ready <none> 66s v1.21.1
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server49 Ready <none> 24s v1.21.1
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server50 Ready <none> 19s v1.21.1
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```
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### Configuring networking
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* This customised calico.yaml enables IPv6
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```
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kubectl apply -f cni-calico/calico.yaml
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```
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After applying, check that all calico pods are up and running:
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```
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% kubectl -n kube-system get pods
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NAME READY STATUS RESTARTS AGE
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calico-kube-controllers-b656ddcfc-5kfg6 0/1 Running 4 3m27s
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calico-node-975vh 1/1 Running 3 3m28s
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calico-node-gbnvj 1/1 Running 2 3m28s
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calico-node-qjm5v 0/1 Running 4 113s
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calico-node-xxxmk 1/1 Running 4 3m28s
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coredns-558bd4d5db-56dv9 1/1 Running 0 8m51s
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coredns-558bd4d5db-hsspb 1/1 Running 0 8m51s
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etcd-server47 1/1 Running 0 9m9s
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kube-apiserver-server47 1/1 Running 0 9m4s
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kube-controller-manager-server47 1/1 Running 0 9m4s
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kube-proxy-5g5qm 1/1 Running 0 8m51s
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kube-proxy-85mck 1/1 Running 0 7m8s
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kube-proxy-b95sv 1/1 Running 0 7m13s
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kube-proxy-mpjkm 1/1 Running 0 7m55s
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kube-scheduler-server47 1/1 Running 0 9m10s
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```
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Often you will have some pods crashing in the beginning and you might
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need to make mounts shared (if they are not) like this:
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```
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mount --make-shared /sys
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mount --make-shared /run
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```
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(above mounts are necessary for Alpine Linux)
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### Getting calicoctl
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To configure calico, we need calicoctl, which we can run in
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yet-another-pod as following:
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```
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kubectl apply -f https://docs.projectcalico.org/manifests/calicoctl.yaml
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```
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And we alias it for easier usage:
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```
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alias calicoctl="kubectl exec -i -n kube-system calicoctl -- /calicoctl"
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```
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### Adding BGP peering
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We need to tell calico with which BGP peers to peer with. For this we
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use the bgp-c2.yaml file, which has configurations fitting for our
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cluster:
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```
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calicoctl create -f - < cni-calico/bgp-c2.yaml
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```
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At this point all nodes should be peering with our upstream
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infrastructure.
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We can confirm this on the upstream side, where we also run bird:
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```
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% birdc show route
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BIRD 2.0.7 ready.
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Table master6:
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2a0a:e5c0:13:e1:f4c5:ab65:a67f:53c0/122 unicast [place7-server1 20:04:14.222] * (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:3554 on eth0
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unicast [place7-server3 20:04:14.224] (100) [AS65534i]
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via 2a0a:e5c0:13:0:224:81ff:fee0:db7a on eth0
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unicast [place7-server2 20:04:14.222] (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:38cc on eth0
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unicast [place7-server4 20:04:14.221] (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:3564 on eth0
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2a0a:e5c0:13:e2::/108 unicast [place7-server1 20:04:14.222] * (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:3554 on eth0
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unicast [place7-server2 20:04:14.222] (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:38cc on eth0
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unicast [place7-server3 20:04:14.113] (100) [AS65534i]
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via 2a0a:e5c0:13:0:224:81ff:fee0:db7a on eth0
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unicast [place7-server4 20:04:14.221] (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:3564 on eth0
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2a0a:e5c0:13:e1:176b:eaa6:6d47:1c40/122 unicast [place7-server1 20:04:14.222] * (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:3554 on eth0
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unicast [place7-server2 20:04:14.222] (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:38cc on eth0
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unicast [place7-server3 20:04:14.221] (100) [AS65534i]
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via 2a0a:e5c0:13:0:224:81ff:fee0:db7a on eth0
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unicast [place7-server4 20:04:14.221] (100) [AS65534i]
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via 2a0a:e5c0:13:0:225:b3ff:fe20:3564 on eth0
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2a0a:e5c0:13::/48 unreachable [v6 2021-05-16] * (200)
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```
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### Testing the cluster
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At this point we should have a functioning k8s cluster, now we should
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test whether it works using a simple nginx deployment:
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Do *NOT* use https://k8s.io/examples/application/deployment.yaml. It
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contains an outdated nginx container that has no IPv6 listener. You
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will get results such as
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```
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% curl http://[2a0a:e5c0:13:bbb:176b:eaa6:6d47:1c41]
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curl: (7) Failed to connect to 2a0a:e5c0:13:bbb:176b:eaa6:6d47:1c41 port 80: Connection refused
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```
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if you use that deployment. Instead use something on the line of the
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included **nginx-test-deployment.yaml**:
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```
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kubectl apply -f generic/nginx-test-deployment.yaml
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```
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Let's see whether the pods are coming up:
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```
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% kubectl get pods
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NAME READY STATUS RESTARTS AGE
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nginx-deployment-95d596f7b-484mz 1/1 Running 0 13s
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nginx-deployment-95d596f7b-4wfkp 1/1 Running 0 13s
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```
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And the associated service:
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```
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% kubectl get svc
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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kubernetes ClusterIP 2a0a:e5c0:13:e2::1 <none> 443/TCP 16m
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nginx-service ClusterIP 2a0a:e5c0:13:e2::4412 <none> 80/TCP 34s
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```
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It is up and running, let's curl it!
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```
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% curl -I http://[2a0a:e5c0:13:e2::4412]
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HTTP/1.1 200 OK
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Server: nginx/1.20.0
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Date: Mon, 14 Jun 2021 18:08:29 GMT
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Content-Type: text/html
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Content-Length: 612
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Last-Modified: Tue, 20 Apr 2021 16:11:05 GMT
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Connection: keep-alive
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ETag: "607efd19-264"
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Accept-Ranges: bytes
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```
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Perfect. Let's delete it again:
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```
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kubectl delete -f generic/nginx-test-deployment.yaml
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```
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### Next steps
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While above is already a fully running k8s cluster, we do want to have
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support for **PersistentVolumeclaims**. See [the rook
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documentation](rook/README.md) on how to achieve the next step.
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## The IPv4 "problem"
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* Clusters are IPv6 only
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* Need to have one or more services to map IPv4
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* Maybe outside haproxy w/ generic ssl/sni/host mapping
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* Could even be **inside** haproxy service
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