Can't install Kubernetes on Vagrant

Question

Use this guide to install Kubernetes on Vagrant cluster:

https://kubernetes.io/docs/getting-started-guides/kubeadm/

At (2/4) Initializing your master, there came some errors:

[root@localhost ~]# kubeadm init
[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[init] Using Kubernetes version: v1.6.4
[init] Using Authorization mode: RBAC
[preflight] Running pre-flight checks
[preflight] Some fatal errors occurred:
    /proc/sys/net/bridge/bridge-nf-call-iptables contents are not set to 1
[preflight] If you know what you are doing, you can skip pre-flight checks with `--skip-preflight-checks`

I checked the /proc/sys/net/bridge/bridge-nf-call-iptables file content, there is only one 0 in it.

At (3/4) Installing a pod network, I downloaded kube-flannel file:

https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

And run kubectl apply -f kube-flannel.yml, got error:

[root@localhost ~]# kubectl apply -f kube-flannel.yml
The connection to the server localhost:8080 was refused - did you specify the right host or port?

Until here, I don't know how to goon.

My Vagrantfile:

  # Master Server
  config.vm.define "master", primary: true do |master|
    master.vm.network :private_network, ip: "192.168.33.200"
    master.vm.network :forwarded_port, guest: 22, host: 1234, id: 'ssh'
  end

Canale

Is that the full Vagrantfile that someone could use to reproduce the issue? Specifically, it is not clear what base image you are using. Also, what other commands were run after kubeadm init? If you could clarify this in your question so it is easier to reproduce that would be helpful. – Adolescence

Did you successfully install master using kubeadm init ? Did you export the location on the KUBECONFIG file as specified in the doc you mentioned? – Jaquelynjaquenetta

@AndyShinn @chaitukopparthi kubeadm init was okay. It generated a token, too. But now the problem is that can't join to master host from nodes hosts. I created a new question here: #44132679 – Canale

Answer 1

In order to set /proc/sys/net/bridge/bridge-nf-call-iptables by editing /etc/sysctl.conf. There you can add [1]

net.bridge.bridge-nf-call-iptables = 1

Then execute

sudo sysctl -p

And the changes will be applied. With this the pre-flight check should pass.

---

[1] http://wiki.libvirt.org/page/Net.bridge.bridge-nf-call_and_sysctl.conf

Revelatory

Answer 2

Update @2019/09/02

Sometimes modprobe br_netfilter is unreliable, you may need to redo it after relogin, so use the following instead when on a systemd sytem:

echo br_netfilter > /etc/modules-load.d/br_netfilter.conf
systemctl restart systemd-modules-load.service
echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables
echo 1 > /proc/sys/net/bridge/bridge-nf-call-ip6tables

---

YES, the accepted answer is right, but I faced with

cannot stat /proc/sys/net/bridge/bridge-nf-call-ip6tables: No such file or directory

So I did

modprobe br_netfilter

echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables
echo 1 > /proc/sys/net/bridge/bridge-nf-call-ip6tables
sudo sysctl -p

Then solved.

Pulling

you save my life, it appear the k8s need this file after some crash issues happend. – Lecturer

Answer 3

On Ubuntu 16.04 I just had to:

modprobe br_netfilter

Default value in /proc/sys/net/bridge/bridge-nf-call-iptables is already 1.

Then I added br_netfilter to /etc/modules to load the module automatically on next boot.

Illa

Had to do this on Ubuntu 22.04 too (AWS). – Embattle

Answer 4

As mentioned in K8s docs - Installing kubeadm under the Letting iptables see bridged traffic section:

Make sure that the br_netfilter module is loaded. This can be done by running lsmod | grep br_netfilter.
To load it explicitly call sudo modprobe br_netfilter.

As a requirement for your Linux Node's iptables to correctly see bridged traffic, you should ensure net.bridge.bridge-nf-call-iptables is set to 1 in your sysctl config, e.g.

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sudo sysctl --system

---

Regardng the preflight erros - you can see in Kubeadm Implementation details under the preflight-checks:

Kubeadm executes a set of preflight checks before starting the init, with the aim to verify preconditions and avoid common cluster startup problems..

The following missing configurations will produce errors:

.
.
if /proc/sys/net/bridge/bridge-nf-call-iptables file does not exist/does not contain 1

if advertise address is ipv6 and /proc/sys/net/bridge/bridge-nf-call-ip6tables does not exist/does not contain 1.

if swap is on
.
.

Abomination

Answer 5

The one-liner way:

sysctl net.bridge.bridge-nf-call-iptables=1

Tomtom

Answer 6

**Vagrant up a kubernetes cluster for self-learning (Virtualbox / Ansible) **

https://www.linkedin.com/pulse/vagrant-up-kubernetes-cluster-self-learning-gary-tay/?trackingId=ld6avdaEQ6eXAsMIJfzJgA%3D%3D

Hi All, I received help from StackOverflow, this How-To is my contribution back.

Environment: Windows 11 Insider, Vagrant 2.4.1, Virtualbox 7.0.18

How to get it up and running?

if you are using CYGWIN64 or MINGW64 Git Bash CLI

$ git clone https://github.com/garyttt/kubernetes-localhost.git
$ cd kubernetes-localhost
$ vagrant plugin install vagrant-vbguest
$ vagrant up 

if you are using Windows CMD or PowerShell CLI

> git clone https://github.com/garyttt/kubernetes-localhost.git
> cd kubernetes-localhost
> vagrant plugin install vagrant-vbguest
> vagrant up

After about 45 minutes you will have a kubernetes localhost cluster up and running, you can SSH (CYGWIN64 or Git Bash or PuTTY or any SSH Client) into the master node to check.

$ alias ssh_k8m='ssh -o "StrictHostKeyChecking no" -i /mnt/c/Users/gtay/.vagrant.d/insecure_private_key [email protected]'
$ ssh_k8m

From the vagrant user at k8s-master host, you can run 'kubectl' to check 'cluster-info' and 'get nodes'.

That's all folks, hope you like it.

Jaenicke

Answer 7

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
EOF

# Apply sysctl params without reboot
sudo sysctl --system

I have created a vagrant kubernetes cluster. check it out it: https://github.com/zaidsasa/vagrant-kubernetes-cluster

Conover

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. – Ladd