Install a single-node k8s cluster

install-k8s.sh

# install k8s on a single node (centos7.4):
# this is mostly based on: https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/

# to run from outside the node:
# scp install-k8s.sh root@<node>:~ && ssh root@<node> "bash ./install-k8s.sh"

# install and enable docker
yum install -y docker
systemctl enable docker && systemctl start docker

# permanently disable selinux
setenforce 0
sed -i 's/^SELINUX=.*/SELINUX=permissive/' /etc/selinux/config

# permanently disable swap file
swapoff -a
sed -i.bak '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

# open ports in firewalld
# firewall-cmd --zone=public --permanent --add-port=6443/tcp
# firewall-cmd --zone=public --permanent --add-port=10250/tcp
# or better, just disable firewalld
systemctl stop firewalld
systemctl disable firewalld

# set k8s repo
if [ ! -f /etc/yum.repos.d/kubernetes.repo ]; then
    cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF
fi

# in Fedora28 socat package is not installed by default, should be installed manually, e.g.
# dnf install -y http://dl.fedoraproject.org/pub/fedora/linux/releases/28/Everything/x86_64/os/Packages/s/socat-1.7.3.2-6.fc28.x86_64.rpm

# install k8s
yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet

# following may be needed:
# echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables

# start cluster
kubeadm init --pod-network-cidr=10.244.0.0/16

# to run kubectl from inside the node first do:
mkdir -p /$USER/.kube && cp /etc/kubernetes/admin.conf /$USER/.kube/config

# deploy flannel - dns pod will be pending until a network plugin is set
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.10.0/Documentation/kube-flannel.yml
# or alternatively, some other CNI, e.g. weave:
# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"

# taint master - since we have a single node cluster
kubectl taint nodes --all node-role.kubernetes.io/master-

# from outside the node:

# install kubectl...

# copy config locally:
# scp root@<node>:/etc/kubernetes/admin.conf .

# then use: kubectl --kubeconfig=./admin.conf ...

# skydive

# for better understanding of networking, run the skydive (http://skydive.network/) on the node (it runs inside docker):
# docker run --restart unless-stopped -d --privileged --pid=host --net=host -p 8081:8081 -e SKYDIVE_ANALYZERS=localhost:8082 -v /var/run/docker.sock:/var/run/docker.sock skydive/skydive agent
# docker run --restart unless-stopped -d -p 8082:8082 skydive/skydive analyzer

# then to access, use: http://<node>:8082/topology