* You can choose where to install the master components. If you want your master node to act both as master (api,scheduler,controller) and node (e.g. accept workloads, create pods ...),
the server address has to be present on both groups 'kube-master' and 'kube-node'.
* For safety reasons, you should have at least two master nodes and 3 etcd servers
* Kube-proxy doesn't support multiple apiservers on startup ([Issue 18174](https://github.com/kubernetes/kubernetes/issues/18174)). An external loadbalancer needs to be configured.
In order to do so, some variables have to be used '**loadbalancer_apiserver**' and '**apiserver_loadbalancer_domain_name**'
### Network Plugin
You can choose between 3 network plugins. Only one must be chosen.
* **weave**: Weave is a lightweight container overlay network that doesn't require an external K/V database cluster. ([official docs](http://weave.works/docs/))
The choice is defined with the variable **kube_network_plugin**
### Check cluster status
#### Kubernetes components
* Check the status of the processes
```
systemctl status kubelet
```
* Check the logs
```
journalctl -ae -u kubelet
```
* Check the NAT rules
```
iptables -nLv -t nat
```
For the master nodes you'll have to see the docker logs for the apiserver
```
docker logs [apiserver docker id]
```
### Available apps, installation procedure
There are two ways of installing new apps
#### Ansible galaxy
Additionnal apps can be installed with ```ansible-galaxy```.
you'll need to edit the file '*requirements.yml*' in order to chose needed apps.
The list of available apps are available [there](https://github.com/ansibl8s)
For instance it is **strongly recommanded** to install a dns server which resolves kubernetes service names.
In order to use this role you'll need the following entries in the file '*requirements.yml*'
Please refer to the [k8s-kubedns readme](https://github.com/ansibl8s/k8s-kubedns) for additionnal info.
Alternatively the roles can be installed as git submodules.
That way is easier if you want to do some changes and commit them.
### Networking
#### Calico
Check if the calico-node container is running
```
docker ps | grep calico
```
The **calicoctl** command allows to check the status of the network workloads.
* Check the status of Calico nodes
```
calicoctl status
```
* Show the configured network subnet for containers
```
calicoctl pool show
```
* Show the workloads (ip addresses of containers and their located)
```
calicoctl endpoint show --detail
```
##### Optionnal : BGP Peering with border routers
In some cases you may want to route the pods subnet and so NAT is not needed on the nodes.
For instance if you have a cluster spread on different locations and you want your pods to talk each other no matter where they are located.
The following variables need to be set:
**peer_with_router** enable the peering with border router of the datacenter (default value: false).
you'll need to edit the inventory and add a and a hostvar **local_as** by node.
```
node1 ansible_ssh_host=95.54.0.12 local_as=xxxxxx
```
#### Flannel
You can choose the [backend](https://github.com/coreos/flannel/blob/master/README.md) type by changing the variable **flannel_backend_type** (default: vxlan)
* Flannel configuration file should have been created there
```
cat /run/flannel/subnet.env
FLANNEL_NETWORK=10.233.0.0/18
FLANNEL_SUBNET=10.233.16.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=false
```
* Check if the network interface has been created
```
ip a show dev flannel.1
4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default
