320 lines
9.4 KiB
Markdown
320 lines
9.4 KiB
Markdown
[](https://travis-ci.org/ansibl8s/setup-kubernetes)
|
|
kubernetes-ansible
|
|
========
|
|
|
|
This project allows to
|
|
- Install and configure a **Multi-Master/HA kubernetes** cluster.
|
|
- Choose the **network plugin** to be used within the cluster
|
|
- A **set of roles** in order to install applications over the k8s cluster
|
|
- A **flexible method** which helps to create new roles for apps.
|
|
|
|
Linux distributions tested:
|
|
* **Debian** Wheezy, Jessie
|
|
* **Ubuntu** 14.10, 15.04, 15.10
|
|
* **Fedora** 23
|
|
* **CentOS** 7 (Currently with flannel only)
|
|
|
|
### Requirements
|
|
* The target servers must have **access to the Internet** in order to pull docker imaqes.
|
|
* The firewalls are not managed, you'll need to implement your own rules the way you used to.
|
|
in order to avoid any issue during deployment you should **disable your firewall**
|
|
* **Copy your ssh keys** to all the servers part of your inventory.
|
|
* **Ansible v1.9.x/v2.x and python-netaddr**
|
|
* Base knowledge on Ansible. Please refer to [Ansible documentation](http://www.ansible.com/how-ansible-works)
|
|
|
|
### Components
|
|
* [kubernetes](https://github.com/kubernetes/kubernetes/releases) v1.1.4
|
|
* [etcd](https://github.com/coreos/etcd/releases) v2.2.4
|
|
* [calicoctl](https://github.com/projectcalico/calico-docker/releases) v0.14.0
|
|
* [flanneld](https://github.com/coreos/flannel/releases) v0.5.5
|
|
* [docker](https://www.docker.com/) v1.9.1
|
|
|
|
Quickstart
|
|
-------------------------
|
|
The following steps will quickly setup a kubernetes cluster with default configuration.
|
|
These defaults are good for tests purposes.
|
|
|
|
Edit the inventory according to the number of servers
|
|
```
|
|
[kube-master]
|
|
10.115.99.31
|
|
|
|
[etcd]
|
|
10.115.99.31
|
|
10.115.99.32
|
|
10.115.99.33
|
|
|
|
[kube-node]
|
|
10.115.99.32
|
|
10.115.99.33
|
|
|
|
[k8s-cluster:children]
|
|
kube-node
|
|
kube-master
|
|
```
|
|
|
|
Run the playbook
|
|
```
|
|
ansible-playbook -i inventory/inventory.cfg cluster.yml -u root
|
|
```
|
|
|
|
You can jump directly to "*Available apps, installation procedure*"
|
|
|
|
|
|
Ansible
|
|
-------------------------
|
|
### Variables
|
|
The main variables to change are located in the directory ```inventory/group_vars/all.yml```.
|
|
|
|
### Inventory
|
|
Below is an example of an inventory.
|
|
Note : The bgp vars local_as and peers are not mandatory if the var **'peer_with_router'** is set to false
|
|
By default this variable is set to false and therefore all the nodes are configure in **'node-mesh'** mode.
|
|
In node-mesh mode the nodes peers with all the nodes in order to exchange routes.
|
|
|
|
```
|
|
|
|
[kube-master]
|
|
node1 ansible_ssh_host=10.99.0.26
|
|
node2 ansible_ssh_host=10.99.0.27
|
|
|
|
[etcd]
|
|
node1 ansible_ssh_host=10.99.0.26
|
|
node2 ansible_ssh_host=10.99.0.27
|
|
node3 ansible_ssh_host=10.99.0.4
|
|
|
|
[kube-node]
|
|
node2 ansible_ssh_host=10.99.0.27
|
|
node3 ansible_ssh_host=10.99.0.4
|
|
node4 ansible_ssh_host=10.99.0.5
|
|
node5 ansible_ssh_host=10.99.0.36
|
|
node6 ansible_ssh_host=10.99.0.37
|
|
|
|
[paris]
|
|
node1 ansible_ssh_host=10.99.0.26
|
|
node3 ansible_ssh_host=10.99.0.4 local_as=xxxxxxxx
|
|
node4 ansible_ssh_host=10.99.0.5 local_as=xxxxxxxx
|
|
|
|
[new-york]
|
|
node2 ansible_ssh_host=10.99.0.27
|
|
node5 ansible_ssh_host=10.99.0.36 local_as=xxxxxxxx
|
|
node6 ansible_ssh_host=10.99.0.37 local_as=xxxxxxxx
|
|
|
|
[k8s-cluster:children]
|
|
kube-node
|
|
kube-master
|
|
```
|
|
|
|
### Playbook
|
|
```
|
|
---
|
|
|
|
- hosts: k8s-cluster
|
|
roles:
|
|
- { role: download, tags: download }
|
|
- { role: kubernetes/preinstall, tags: preinstall }
|
|
- { role: docker, tags: docker }
|
|
- { role: kubernetes/node, tags: node }
|
|
- { role: etcd, tags: etcd }
|
|
- { role: dnsmasq, tags: dnsmasq }
|
|
- { role: network_plugin, tags: ['calico', 'flannel', 'network'] }
|
|
|
|
- hosts: kube-master
|
|
roles:
|
|
- { role: kubernetes/master, tags: master }
|
|
|
|
```
|
|
|
|
### Run
|
|
It is possible to define variables for different environments.
|
|
For instance, in order to deploy the cluster on 'dev' environment run the following command.
|
|
```
|
|
ansible-playbook -i inventory/dev/inventory.cfg cluster.yml -u root
|
|
```
|
|
|
|
Kubernetes
|
|
-------------------------
|
|
### Multi master notes
|
|
* 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'.
|
|
|
|
* Almost all kubernetes components are running into pods except *kubelet*. These pods are managed by kubelet which ensure they're always running
|
|
|
|
* 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 Overlay
|
|
You can choose between 2 network plugins. Only one must be chosen.
|
|
|
|
* **flannel**: gre/vxlan (layer 2) networking. ([official docs](https://github.com/coreos/flannel))
|
|
|
|
* **calico**: bgp (layer 3) networking. ([official docs](http://docs.projectcalico.org/en/0.13/))
|
|
|
|
The choice is defined with the variable '**kube_network_plugin**'
|
|
|
|
### Expose a service
|
|
There are several loadbalancing solutions.
|
|
The one i found suitable for kubernetes are [Vulcand](http://vulcand.io/) and [Haproxy](http://www.haproxy.org/)
|
|
|
|
My cluster is working with haproxy and kubernetes services are configured with the loadbalancing type '**nodePort**'.
|
|
eg: each node opens the same tcp port and forwards the traffic to the target pod wherever it is located.
|
|
|
|
Then Haproxy can be configured to request kubernetes's api in order to loadbalance on the proper tcp port on the nodes.
|
|
|
|
Please refer to the proper kubernetes documentation on [Services](https://github.com/kubernetes/kubernetes/blob/release-1.0/docs/user-guide/services.md)
|
|
|
|
### 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```.
|
|
|
|
ou'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.
|
|
```
|
|
- src: https://github.com/ansibl8s/k8s-common.git
|
|
path: roles/apps
|
|
# version: v1.0
|
|
|
|
- src: https://github.com/ansibl8s/k8s-kubedns.git
|
|
path: roles/apps
|
|
# version: v1.0
|
|
```
|
|
**Note**: the role common is required by all the apps and provides the tasks and libraries needed.
|
|
|
|
And empty the apps directory
|
|
```
|
|
rm -rf roles/apps/*
|
|
```
|
|
|
|
Then download the roles with ansible-galaxy
|
|
```
|
|
ansible-galaxy install -r requirements.yml
|
|
```
|
|
|
|
Finally update the playbook ```apps.yml``` with the chosen roles, and run it
|
|
```
|
|
...
|
|
- hosts: kube-master
|
|
roles:
|
|
- { role: apps/k8s-kubedns, tags: ['kubedns', 'apps'] }
|
|
...
|
|
```
|
|
|
|
```
|
|
ansible-playbook -i inventory/inventory.cfg apps.yml -u root
|
|
```
|
|
|
|
#### Git submodules
|
|
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
|
|
```
|
|
|
|
#### Flannel
|
|
|
|
* 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
|
|
link/ether e2:f3:a7:0f:bf:cb brd ff:ff:ff:ff:ff:ff
|
|
inet 10.233.16.0/18 scope global flannel.1
|
|
valid_lft forever preferred_lft forever
|
|
inet6 fe80::e0f3:a7ff:fe0f:bfcb/64 scope link
|
|
valid_lft forever preferred_lft forever
|
|
```
|
|
|
|
* Docker must be configured with a bridge ip in the flannel subnet.
|
|
```
|
|
ps aux | grep docker
|
|
root 20196 1.7 2.7 1260616 56840 ? Ssl 10:18 0:07 /usr/bin/docker daemon --bip=10.233.16.1/24 --mtu=1450
|
|
```
|
|
|
|
* Try to run a container and check its ip address
|
|
```
|
|
kubectl run test --image=busybox --command -- tail -f /dev/null
|
|
replicationcontroller "test" created
|
|
|
|
kubectl describe po test-34ozs | grep ^IP
|
|
IP: 10.233.16.2
|
|
```
|
|
|
|
```
|
|
kubectl exec test-34ozs -- ip a show dev eth0
|
|
8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1450 qdisc noqueue
|
|
link/ether 02:42:0a:e9:2b:03 brd ff:ff:ff:ff:ff:ff
|
|
inet 10.233.16.2/24 scope global eth0
|
|
valid_lft forever preferred_lft forever
|
|
inet6 fe80::42:aff:fee9:2b03/64 scope link tentative flags 08
|
|
valid_lft forever preferred_lft forever
|
|
```
|
|
|
|
|
|
Congrats ! now you can walk through [kubernetes basics](http://kubernetes.io/v1.1/basicstutorials.html)
|