Configuring Kubernetes on Fedora via Ansible offers a simple way to quickly create a clustered environment with little effort.
* TOC
{:toc}
## Prerequisites
1. Host able to run ansible and able to clone the following repo: [kubernetes](https://github.com/kubernetes/kubernetes.git)
2. A Fedora 21+ host to act as cluster master
3. 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:
**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.
```shell
[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
```yaml
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](#setting-up-the-cluster)
Make sure your local machine (root) has an ssh key pair if not
```shell
ssh-keygen
```
Copy the ssh public key to **all** nodes in the cluster
```shell
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.
```conf
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.
```yaml
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.
```yaml
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.
```yaml
cluster_logging: true
```
Turn `cluster_monitoring` to true (default) or false to enable or disable cluster monitoring with heapster and influxdb.
```yaml
cluster_monitoring: true
```
Turn `dns_setup` to true (recommended) or false to enable or disable whole DNS configuration.
```yaml
dns_setup: true
```
**Tell ansible to get to work!**
This will finally setup your whole Kubernetes cluster for you.
```shell
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:
```shell
kubectl get nodes
```
**Show services running on masters and nodes**
```shell
systemctl | grep -i kube
```
**Show firewall rules on the masters and nodes**
```shell
iptables -nvL
```
**Create /tmp/apache.json on the master with the following contents and deploy pod**
```json
{
"kind": "Pod",
"apiVersion": "v1",
"metadata": {
"name": "fedoraapache",
"labels": {
"name": "fedoraapache"
}
},
"spec": {
"containers": [
{
"name": "fedoraapache",
"image": "fedora/apache",
"ports": [
{
"hostPort": 80,
"containerPort": 80
}
]
}
]
}
}
```
```shell
kubectl create -f /tmp/apache.json
```
**Check where the pod was created**
```shell
kubectl get pods
```
**Check Docker status on nodes**
```shell
docker ps
docker images
```
**After the pod is 'Running' Check web server access on the node**
```shell
curl http://localhost
```
That's it !
## Support Level
IaaS Provider | Config. Mgmt | OS | Networking | Docs | Conforms | Support Level
