# Kooking Kontainers With Kubernetes: A Recipe for Dual-Stack Deliciousness

- Link: https://www.agilicus.com/kooking-kontainers-with-kubernetes-a-recipe-for-dual-stack-deliciousness/
- Published: 2019-04-05T19:41:00+00:00
- Author: Don Bowman

If you have a mild allergy to [ASCII](https://en.wikipedia.org/wiki/ASCII) or [YAML](https://en.wikipedia.org/wiki/YAML)
you might want to avert your eyes. You’ve been warned.

Now, lets imagine you have a largish server hanging around, not earning its keep.
And on the other hand, you have a desire to run some CI pipelines on it, and think
Kubernetes is the answer.

You’ve tried ‘kube-spawn’ and ‘minikube’ etc, but they stubbornly allocate just 
a ipv4/32 to your container, and, well, your CI job does something ridiculous like
bind to ::1, failing miserably. Don’t despair, lets use Calico with a host-local
ipam.

For the most part the recipe speaks for itself. The ‘awk’ in the calico install 
is to switch from calico-ipam (single-stack) to host-local with 2 sets of ranges.
Technically Kubernetes doesn’t support dual stack (cloud networking is terrible.
Just terrible. its all v4 and proxy server despite sometimes using advanced things
like BGP). But, we’ll fool it!

Well, here’s the recipe. Take one server running ubuntu 18.04 (probably works with
anything), run as follows, sit back and enjoy, then install your gitlab-runner.

    ```
    rm -rf ~/.kube
    sudo kubeadm reset -f
    sudo kubeadm init --apiserver-advertise-address 172.16.0.3 --pod-network-cidr 192.168.0.0/16 
    mkdir -p $HOME/.kube
    sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
    sudo chown $(id -u):$(id -g) $HOME/.kube/config

    until kubectl get nodes; do echo -n .; sleep 1; done; echo              

    kubectl apply -f \
     https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/hosted/etcd.yaml
    kubectl apply -f \
     https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/rbac.yaml

    curl -s https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/hosted/calico.yaml |\
      awk '/calico-ipam/ { print "              \"type\": \"host-local\",\n"
                         print "              \"ranges\": [ [ { \"subnet\": \"192.168.0.0/16\", \"rangeStart\": \"192.168.0.10\", \"rangeEnd\": \"192.168.255.254\" } ], [ { \"subnet\": \"fc00::/64\", \"rangeStart\": \"fc00:0:0:0:0:0:0:10\", \"rangeEnd\": \"fc00:0:0:0:ffff:ffff:ffff:fffe\" } ] ]"
                         printed=1
    }
    {
        if (!printed) {
            print $0
        }
        printed = 0;
    }' > /tmp/calico.yaml

    kubectl apply -f /tmp/calico.yaml

    kubectl apply -f - << EOF
    kind: ConfigMap
    metadata:
      name: coredns
      namespace: kube-system
    apiVersion: v1
    data:
      Corefile: |
        .:53 {
            errors
            health
            kubernetes cluster.local in-addr.arpa ip6.arpa {
               pods insecure
               upstream
               fallthrough in-addr.arpa ip6.arpa
            }
            prometheus :9153
            proxy . 8.8.8.8
            cache 30
            reload
            loadbalance
        }
    EOF

    kubectl taint nodes --all node-role.kubernetes.io/master-

    kubectl create serviceaccount -n kube-system tiller
    kubectl create clusterrolebinding tiller-binding --clusterrole=cluster-admin --serviceaccount kube-system:tiller
    helm init --service-account tiller                
    ```