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kubectl get pods -A -o wide | grep dns
kube-system   kube-dns-5bfd847c64-bkkhf                           4/4     Running   0             80m   10.108.0.5    gke-vanilla-default-pool-ddebe65c-pkzw   <none>           <none>

kubectl debug -n kube-system -it kube-dns-5bfd847c64-bkkhf --image=busybox:1.28 --target=dnsmasq
Targeting container "dnsmasq". If you don't see processes from this container it may be because the container runtime doesn't support this feature.
Defaulting debug container name to debugger-qz6cb.
If you don't see a command prompt, try pressing enter.

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apiVersion: v1
kind: Pod
metadata:
  name: job1
  labels:
    job-name: "job1"
    job-index: "0"
spec:
  hostNetwork: true
  containers:

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apiVersion: apps/v1
kind: Deployment
metadata:
  name: netperf-server
  labels:
    app: netperf-server
spec:
  replicas: 1
  selector:
    matchLabels:

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Create the deploymentn with 100 backends and one Service

kubectl apply -f backends.yaml

Run a pod to test the Service using the httptest program, that allows to specify different parameters of the http connections

./httptest -h
Usage: httpget [options] [url]

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BPF Cheatsheet

Download binary

curl -s -L https://github.com/libbpf/bpftool/releases/download/v7.2.0/bpftool-v7.2.0-amd64.tar.gz | tar xvzf - -C /tmp chmod +x /tmp/bpftool

List network

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Service LoadBalancer deletion

Services of Type: LoadBalancer are handled by external controllers.

These controllers need to handle the infrastructure necessary to provisiong the external Loadbalancer, and use finalizers to avoid deleting the Service before all the necessary steps are done.

Kubernetes provide a reference implementation of a controller for Loadbalancers in https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/cloud-provider/controllers/service/controller.go

Example

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checkout cilium repo and run it in kind

git clone https://github.com/cilium/cilium.git
cd cilium
REPO_ROOT=$PWD
KUBEPROXY_MODE="none" make kind
make kind-image
make kind-install-cilium

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Install ingress-nginx

kubectl create clusterrolebinding cluster-admin-binding   --clusterrole cluster-admin   --user $(gcloud config get-value account)
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.7.0/deploy/static/provider/cloud/deploy.yaml

Scale the ingress-controller to have two replicas:

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$ wget https://gist.githubusercontent.com/aojea/50ec0d10807d1907ecc6ece526f991da/raw/15371f0f2cf48f2e6a75db7f71a7e674e8dfc624/ipmasq.yaml -O ipmasq-noop.yaml

$ kubectl apply -f ipmasq-noop.yaml
configmap/ip-masq-agent configured
daemonset.apps/ip-masq-agent unchanged

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GCE IPv6 only cluster

These scripts create an IPv6 only cluster on GCE using GUA for both Pods and Services. The scripts use kubeadm and there are not fully automated, this is some personal and exploratory work, so some manual steps are required.

Using GUAs everywhere allows to connect directly to Pod and Services:

• with the benefit that everything is routed and there is no need for lodabalancers or nodePorts
• with the con that everything is public and you need to create firewall rules accordenly