How to install Kubernetes with Kubeadm: A quick and dirty guide

Nick Chase - October 30, 2017 - containers | k8s | kubeadm | kubernetes

Sometimes you just need a Kubernetes cluster, and you don’t want to mess around. Maybe you want to test out a small application, or create a development environment for yourself. Whatever your goal, you want it quick, and you want it simple. That’s what we’re going to do. This article is a quick and dirty guide to creating a single-node Kubernetes cluster using Kubeadm, a new tool the k8s community created to simplify the deployment process. (It’s straightforward to create multi-node deployments, but we’ll cover that in later articles.)

Create the VM

These instructions were tested using a Virtualbox VM, but in theory they should be the same for a bare metal deployment. (You can find instructions for creating the VM here.) A couple of things to note about the VM:

Allocate at least 2 vCPUs, even if you’re overcommitting your resources; there are pieces of this example that won’t start with just one.
Try to allocate at least 4096 MB of RAM and 20 GB of drive space.
You should have Ubuntu 16.04 installed.
Set the default network adapter to connect to the “Bridged adapter” to enable traffic between the VM and the host machine.

Prepare the VM

There are a few things you need to do to get the VM ready. Specifically, you need to turn off the swap, tweak some settings, and make sure you have the prerequisites installed. To do that, follow these steps:

Change to root:
```
sudo su
```

Turn off swap: To do this, you will first need to turn it off directly …

swapoff -a

… then comment out the reference to swap in /etc/fstab. Start by editing the file:

vi /etc/fstab

Then comment out the appropriate line, as in:

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>    <dump>  <pass>
# / was on /dev/sda1 during installation
UUID=1d343a19-bd75-47a6-899d-7c8bc93e28ff /            ext4 errors=remount-ro 0    1
# swap was on /dev/sda5 during installation
#UUID=d0200036-b211-4e6e-a194-ac2e51dfb27d none         swap sw           0    0

Now configure iptables to receive bridged network traffic. First edit the sysctl.conf file:

vi /etc/ufw/sysctl.conf

And add the following lines to the end:

net/bridge/bridge-nf-call-ip6tables = 1
net/bridge/bridge-nf-call-iptables = 1
net/bridge/bridge-nf-call-arptables = 1

Reboot so the changes take effect.

Install ebtables and ethtool:

sudo su
apt-get install ebtables ethtool

Reboot once more.

Install Kubeadm

OK, now we’re ready to go ahead and do the install. For a full description of this process, you can see the documentation, but here’s the quick and dirty version:

Install Docker:

sudo su

apt-get update
apt-get install -y docker.io

Install HTTPS support (if necessary):

apt-get update 
apt-get install -y apt-transport-https

Install Curl (if necessary):
```
apt-get install curl
```

Retrieve the key for the Kubernetes repo and add it to your key manager:

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -

Add the kubernetes repo to your system.

cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF

Actually install the three pieces you’ll need, kubeadm, kubelet, and kubectl:
```
apt-get update
apt-get install -y kubelet kubeadm kubectl
```

At this point you should have all the tools you need, so you should be ready to go ahead and actually deploy a k8s cluster.

Create a cluster

Now that we have Kubeadm installed, we’ll go ahead and create a new cluster. Part of this process is choosing a network provider, and there are several choices; we’ll use Calico for this example.

Create the actual cluster. For Calico, we need to add the –pod-network-cidr switch, as in:

kubeadm init --pod-network-cidr=192.168.0.0/16

This will crank for a while, eventually giving you output something like this:

To start using your cluster, you need to run (as a regular user):

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  http://kubernetes.io/docs/admin/addons/

You can now join any number of machines by running the following on each node
as root:

  kubeadm join --token 354502.d6a9a425d5fa8f2e 192.168.0.9:6443 --discovery-token-ca-cert-hash sha256:ad7c5e8a0c909ed36a87452e65fa44b1c2a9729cef7285eb551e2f126a1d6a54

Notice that last bit, about joining other machines to the cluster; we’re not going to do that, but you do have that option.

Prepare your system for adding workloads, including the network plugin. Open a NEW terminal window and execute the commands kubeadm gave you:
```
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
```

Install the Calico network plugin:

kubectl apply -f https://docs.projectcalico.org/v2.6/getting-started/kubernetes/installation/hosted/kubeadm/1.6/calico.yaml

Check to see if the pods are running:
```
kubectl get pods --all-namespaces
```
The pods will start up over a short period of time.
Untaint the master so that it will be available for scheduling workloads:
```
kubectl taint nodes --all node-role.kubernetes.io/master-
```

At this point you should have a fully-functional kubernetes cluster on which you can run workloads.

Test the cluster

Now let’s make sure everything’s working properly by installing the Sock Shop sample application. Follow these steps:

Create the namespace in which the Sock Shop will live:
```
kubectl create namespace sock-shop
```

Create the actual Sock Shop application:

kubectl apply -n sock-shop -f "https://github.com/microservices-demo/microservices-demo/blob/master/deploy/kubernetes/complete-demo.yaml?raw=true"

Use kubectl get pods –all-namespaces to make sure the pods are all running.

We’ll interact with it via the front-end service, so find the IP address for that service:
```
kubectl -n sock-shop get svc front-end

NAME        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
front-end   10.110.250.153   <nodes>       80:30001/TCP   59s
```
Visit http://<cluster-ip> (in this case, http://10.110.250.153) with your browser. You should see the WeaveSocks interface:

(NOTE: If you are running VirtalBox on Windows, you may run into a bug that only enables you to view the application on port 30001.)

You can also verify that you can reach the interface from the host machine. You’ll first need to find the proper IP address. Your VM will have several, which you should be able to find using:

ifconfig

You’re looking for an IP address in the same range as your host machine, most likely the Ethernet adapter. For example, in my case, it was this section:

enp0s3 Link encap:Ethernet  HWaddr 08:00:27:7c:14:fd  
       inet addr:192.168.2.50  Bcast:192.168.2.255  Mask:255.255.255.0
       inet6 addr: fe80::7638:2441:3326:b242/64 Scope:Link
       UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
       RX packets:415485 errors:0 dropped:0 overruns:0 frame:0
       TX packets:166889 errors:0 dropped:0 overruns:0 carrier:0
       collisions:0 txqueuelen:1000
       RX bytes:621031284 (621.0 MB)  TX bytes:12020009 (12.0 MB)

Now take that IP address and point the browser on your host machine to that IP on port 30001:
```
http://:30001
```
(In my case that would be http://192.168.2.50:30001.)

If all has gone well, you will see the Sock Shop, just as you did on the VM:

Cleaning up

We haven’t done much, but if you want to start over, you can do the following:

To remove the Sock Shop:

kubectl delete namespace sock-shop

To remove the entire cluster:

sudo kubeadm reset

That’s it!

Moving on

So at this point you know how to:

Prepare a VM for Kubeadm
Install Kubeadm
Deploy a Kubernetes cluster
Deploy a sample application on a Kubernetes application
Remove the sample application
Remove the cluster

In future articles, we’ll talk about tasks such as creating custom applications and adding additional nodes to clusters. You can also check out our previous tutorial on creating a Kubernetes deployment, or spend an hour learning the basics of Kubernetes with our free Kubernetes mini-boot camp.

11 responses to “How to install Kubernetes with Kubeadm: A quick and dirty guide”

Vjacheslav says:

January 19, 2018 at 01:49

ebtables is required to install and load the br_netfilter kernel module into the OS (because it’s Ubuntu)

Reply
Mamta says:

January 30, 2018 at 22:17

Thank you for this document.Can you please give us a link to adding additional nodes to clusters. I am not able to join nodes on my cluster by kubeadm join

Reply
vikas027 says:

February 4, 2018 at 06:28

It would be good if you can also add why one needs to disable swap and configure iptables.

Reply
1. Vjacheslav says:
  
  February 12, 2018 at 07:29
  
  k8s doesn’t like swap enabled machines, it’s prerequisite, and iptables required for interpod network communications
  
  Reply
Phu says:

April 17, 2018 at 06:13

I ran the command line to create the sock shop app and the pods are stuck at pending for almost an hour now. I’m running this on a vm with the recommended spec (4GB of RAM and 2 CPUs). Maybe this is not enough?

phu@ubuntu:~$ kubectl get pods NAMESPACE NAME kube-system calico-etcd-g2dxq kube-system calico-kube-controllers- kube-system calico-node-p7pg7 kube-system etcd-ubuntu kube-system kube-apiserver-ubuntu kube-system kube-controller-manager-ubuntu kube-system kube-dns-86f4d74b45-zvwh9 kube-system kube-proxy-qvv4v kube-system kube-scheduler-ubuntu sock-shop carts-6cd457d86c-wqtvr sock-shop carts-db-784446fdd6-jz29r sock-shop catalogue-779cd58f9b-8rhbl sock-shop catalogue-db-6794f65f5d-28bz5 sock-shop front-end-679d7bcb77-6zxfn sock-shop orders-755bd9f786-kxqzs sock-shop orders-db-84bb8f48d6-7zrjr sock-shop payment-674658f686-nrkmk sock-shop queue-master-5f98bbd67-xv7vc sock-shop rabbitmq-86d44dd846-5nvr8 sock-shop shipping-79786fb956-8vbzg sock-shop user-6995984547-74fcd sock-shop user-db-fc7b47fb9-5p6pj –all-namespaces
READY STATUS RESTARTS AGE
1/1 Running 0 59m
5cc6fcf4d9-cxhg9 1/1 Running 0 59m
2/2 Running 0 59m
1/1 Running 0 1h
1/1 Running 0 1h
1/1 Running 0 1h
3/3 Running 0 1h
1/1 Running 0 1h
1/1 Running 0 1h
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m
0/1 Pending 0 54m

Reply
1. Nick Chase says:
  
  April 20, 2018 at 10:07
  
  Try expanding to 8GB and see what happens.
  
  Reply
Oliver says:

August 6, 2018 at 05:45

Hi there,
I’ve done this and would like to use jenkins to make deployments and other things.
Have you got any experience setting up Jenkins to use kubeadm to remotely connect to a bare-metal k8s cluster?
If not – do you know at all how to set up remote access to a cluster setup like above?

Reply
GeekGuste says:

November 19, 2018 at 02:00

Hi
Thank you for the tutorial.
I follow the tuto but the status of pods remain pending. That is my pods state after the installation of Calico network below. I am running on ubuntu 16.04 on a vps with 16gb of RAM and CPU 2.4Ghz

$ kubectl get pods –all-namespaces

NAMESPACE NAME READY STATUS RESTARTS AGE

kube-system calico-kube-controllers-57c8947c94-rl2j9 0/1 Pending 0 32h
kube-system coredns-576cbf47c7-72xzx 0/1 ContainerCreating 0 32h
kube-system coredns-576cbf47c7-wwtrw 0/1 ContainerCreating 0 32h
kube-system etcd-vps205307 1/1 Running 0 32h
kube-system kube-apiserver-vps205307 1/1 Running 0 32h
kube-system kube-controller-manager-vps205307 1/1 Running 1 32h
kube-system kube-proxy-tjd9j 1/1 Running 0 32h
kube-system kube-scheduler-vps205307 1/1 Running 2 32h

What could be causing this. How to solve this issue?

Reply
GeekGuste says:

November 22, 2018 at 16:10

Hi I am triing to install kubernetes following this tutorial: https://www.mirantis.com/blog/how-install-kubernetes-kubeadm/https://www.mirantis.com/blog/how-install-kubernetes-kubeadm/. After the “kubeadm init” command, all coredns… pods status stay on pending. i am running it on a vps which have RAM is 12GB and 2 CPUs of 2.4GHz.

This is the list of pods below:

$ kubectl get pods –all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-576cbf47c7-5r78j 0/1 Pending 0 9m38s
kube-system coredns-576cbf47c7-98jdp 0/1 Pending 0 9m38s
kube-system etcd-vps205307 1/1 Running 0 8m33s
kube-system kube-apiserver-vps205307 1/1 Running 0 8m38s
kube-system kube-controller-manager-vps205307 1/1 Running 0 8m48s
kube-system kube-proxy-cn8dz 1/1 Running 0 9m38s
kube-system kube-scheduler-vps205307 1/1 Running 0 9m

Reply
Himanshu Dureja says:

December 6, 2018 at 09:44

Why we need to turn off swap ? any specific reason

Reply
Evgeny Sboychakov says:

January 27, 2019 at 11:11

Was able to reproduce the issue with “Pending” pods on AWS/Ubuntu16/2CPU/4GB t3-medium instance.

kubectl get pods –all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system calico-kube-controllers-74bbfbfd85-bb5pl 0/1 Pending 0 122m
kube-system coredns-86c58d9df4-k6klz 0/1 Pending 0 160m
kube-system coredns-86c58d9df4-lj5hk 0/1 Pending 0 160m
kube-system etcd-ip-172-31-8-112 1/1 Running 0 159m
kube-system kube-apiserver-ip-172-31-8-112 1/1 Running 0 159m
kube-system kube-controller-manager-ip-172-31-8-112 1/1 Running 0 159m
kube-system kube-proxy-m8c4n 1/1 Running 0 160m
kube-system kube-scheduler-ip-172-31-8-112 1/1 Running 0 159m

As per log entries looks like it’s CNI config related:

journalctl -xeu kubelet:
Jan 27 16:30:17 ip-172-31-8-112 kubelet[2999]: E0127 16:30:17.401666 2999 kubelet.go:2192] Container runtime network not ready: NetworkReady=false reason:Netwo
Jan 27 16:30:22 ip-172-31-8-112 kubelet[2999]: W0127 16:30:22.402610 2999 cni.go:203] Unable to update cni config: No networks found in /etc/cni/net.d

And here as well:

systemctl status kubelet:
Jan 27 16:40:12 ip-172-31-8-112 kubelet[2999]: W0127 16:40:12.561347 2999 cni.go:203] Unable to update cni config: No networks found in /etc/cni/net.d
Jan 27 16:40:12 ip-172-31-8-112 kubelet[2999]: E0127 16:40:12.561481 2999 kubelet.go:2192] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized

Trying to check config’s dir /etc/cni/net.d shows it is absent. So seems that’s the root cause..
As per Calico installation guide for v2.6 (https://github.com/projectcalico/calico/blob/master/v2.6/getting-started/kubernetes/installation/integration.md) that dir should be added and filled with some data:

mkdir -p /etc/cni/net.d
cat >/etc/cni/net.d/10-calico.conf <<EOF
{
"name": "calico-k8s-network",
"cniVersion": "0.1.0",
"type": "calico",
"etcd_endpoints": "http://:”,
“log_level”: “info”,
“ipam”: {
“type”: “calico-ipam”
},
“policy”: {
“type”: “k8s”
},
“kubernetes”: {
“kubeconfig”: “”
}
}
EOF

When filling out etcd’s actual IP:PORT and kubeconfig’s path here is the result in my case:

cat >/etc/cni/net.d/10-calico.conf <<EOF
{
"name": "calico-k8s-network",
"type": "calico",
"etcd_endpoints": "http://10.96.232.136:6666",
"log_level": "info",
"ipam": {
"type": "calico-ipam"
},
"policy": {
"type": "k8s"
},
"kubernetes": {
"kubeconfig": "/etc/kubernetes/kubelet.conf"
}
}
EOF

Doing that completely eliminates the "Pending" problem:

kubectl get pods –all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system calico-etcd-6hbkv 1/1 Running 0 35m
kube-system calico-kube-controllers-74bbfbfd85-bb5pl 1/1 Running 0 3h59m
kube-system calico-node-9t6pf 2/2 Running 1 35m
kube-system coredns-86c58d9df4-k6klz 1/1 Running 0 4h38m
kube-system coredns-86c58d9df4-lj5hk 1/1 Running 0 4h38m
kube-system etcd-ip-172-31-8-112 1/1 Running 0 4h37m
kube-system kube-apiserver-ip-172-31-8-112 1/1 Running 0 4h37m
kube-system kube-controller-manager-ip-172-31-8-112 1/1 Running 0 4h37m
kube-system kube-proxy-m8c4n 1/1 Running 0 4h38m
kube-system kube-scheduler-ip-172-31-8-112 1/1 Running 0 4h37m

Reply

The Mirantis Blog

How to install Kubernetes with Kubeadm: A quick and dirty guide

Create the VM

Prepare the VM

Install Kubeadm

Create a cluster

Test the cluster

Cleaning up

Moving on

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11 responses to “How to install Kubernetes with Kubeadm: A quick and dirty guide”

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