Configuring Kubernetes on Fedora via Ansible offers a simple way to quickly create a clustered environment with little effort.
- Prerequisites
- Architecture of the cluster
- Setting up ansible access to your nodes
- Setting up the cluster
- Testing and using your new cluster
- Support Level
Prerequisites
- Host able to run ansible and able to clone the following repo: kubernetes
- A Fedora 21+ host to act as cluster master
- As many Fedora 21+ hosts as you would like, that act as cluster nodes
The hosts can be virtual or bare metal. Ansible will take care of the rest of the configuration for you - configuring networking, installing packages, handling the firewall, etc. This example will use one master and two nodes.
Architecture of the cluster
A Kubernetes cluster requires etcd, a master, and n nodes, so we will create a cluster with three hosts, for example:
master,etcd = kube-master.example.com
node1 = kube-node-01.example.com
node2 = kube-node-02.example.com
Make sure your local machine has
- ansible (must be 1.9.0+)
- git
- python-netaddr
If not
yum install -y ansible git python-netaddr
Now clone down the Kubernetes repository
git clone https://github.com/kubernetes/contrib.git
cd contrib/ansible
Tell ansible about each machine and its role in your cluster
Get the IP addresses from the master and nodes. Add those to the ~/contrib/ansible/inventory file on the host running Ansible.
[masters]
kube-master.example.com
[etcd]
kube-master.example.com
[nodes]
kube-node-01.example.com
kube-node-02.example.com
Setting up ansible access to your nodes
If you already are running on a machine which has passwordless ssh access to the kube-master and kube-node-{01,02} nodes, and ‘sudo’ privileges, simply set the value of ansible_ssh_user in ~/contrib/ansible/group_vars/all.yml to the username which you use to ssh to the nodes (i.e. fedora), and proceed to the next step…
Otherwise setup ssh on the machines like so (you will need to know the root password to all machines in the cluster).
edit: ~/contrib/ansible/group_vars/all.yml
ansible_ssh_user: root
Configuring ssh access to the cluster
If you already have ssh access to every machine using ssh public keys you may skip to setting up the cluster
Make sure your local machine (root) has an ssh key pair if not
ssh-keygen
Copy the ssh public key to all nodes in the cluster
for node in kube-master.example.com kube-node-01.example.com kube-node-02.example.com; do
ssh-copy-id ${node}
done
Setting up the cluster
Although the default value of variables in ~/contrib/ansible/group_vars/all.yml should be good enough, if not, change them as needed.
edit: ~/contrib/ansible/group_vars/all.yml
Configure access to kubernetes packages
Modify source_type as below to access kubernetes packages through the package manager.
source_type: packageManager
Configure the IP addresses used for services
Each Kubernetes service gets its own IP address. These are not real IPs. You need only select a range of IPs which are not in use elsewhere in your environment.
kube_service_addresses: 10.254.0.0/16
Managing flannel
Modify flannel_subnet, flannel_prefix and flannel_host_prefix only if defaults are not appropriate for your cluster.
Managing add on services in your cluster
Set cluster_logging to false or true (default) to disable or enable logging with elasticsearch.
cluster_logging: true
Turn cluster_monitoring to true (default) or false to enable or disable cluster monitoring with heapster and influxdb.
cluster_monitoring: true
Turn dns_setup to true (recommended) or false to enable or disable whole DNS configuration.
dns_setup: true
Tell ansible to get to work!
This will finally setup your whole Kubernetes cluster for you.
cd ~/contrib/ansible/
./setup.sh
Testing and using your new cluster
That’s all there is to it. It’s really that easy. At this point you should have a functioning Kubernetes cluster.
Show kubernetes nodes
Run the following on the kube-master:
kubectl get nodes
Show services running on masters and nodes
systemctl | grep -i kube
Show firewall rules on the masters and nodes
iptables -nvL
Create /tmp/apache.json on the master with the following contents and deploy pod
{
"kind": "Pod",
"apiVersion": "v1",
"metadata": {
"name": "fedoraapache",
"labels": {
"name": "fedoraapache"
}
},
"spec": {
"containers": [
{
"name": "fedoraapache",
"image": "fedora/apache",
"ports": [
{
"hostPort": 80,
"containerPort": 80
}
]
}
]
}
}
kubectl create -f /tmp/apache.json
Check where the pod was created
kubectl get pods
Check Docker status on nodes
docker ps
docker images
After the pod is ‘Running’ Check web server access on the node
curl http://localhost
That’s it !
Support Level
| IaaS Provider | Config. Mgmt | OS | Networking | Docs | Conforms | Support Level |
|---|---|---|---|---|---|---|
| Bare-metal | Ansible | Fedora | flannel | docs | Project |
For support level information on all solutions, see the Table of solutions chart.