k3s/docs/getting-started-guides/ubuntu_multinodes_cluster.md

# Kubernetes deployed on multiple ubuntu nodes

This document describes how to deploy kubernetes on multiple ubuntu nodes, including 1 master node and 3 minion nodes, and people uses this approach can scale to **any number of minion nodes** by changing some settings with ease. Although there exists saltstack based ubuntu k8s installation ,  it may be tedious and hard for a guy that knows little about saltstack but want to build a really distributed k8s cluster. This approach is inspired by [k8s deploy on a single node](https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/getting-started-guides/ubuntu_single_node.md).

[Cloud team from ZJU](https://github.com/ZJU-SEL) will keep updating this work.

### **Prerequisites：**
*1 The minion nodes have installed docker version 1.2+* 

*2 All machines can communicate with each orther, no need to connect Internet (should use private docker registry in this case)*

*3 These guide is tested OK on Ubuntu 14.04 LTS 64bit server, but it should also work on most Ubuntu versions*

*4 Dependences of this guide: etcd-2.0.0, flannel-0.2.0, k8s-0.10.1, but it should also work on higher versions*


### **Main Steps**
#### I. Make *kubernetes* , *etcd* and *flanneld* binaries

On your laptop, copy `cluster/ubuntu-cluster` directory to your workspace.

The `build.sh` will download and build all the needed binaries into `./binaries`.
```
$ cd cluster/ubuntu-cluster
$ sudo ./build.sh
```
Please copy all the files in `./binaries` into `/opt/bin` of every machine you want to run as Kubernetes cluster node.


Alternatively, if your Kubernetes nodes have access to Internet, you can copy `cluster/ubuntu-cluster` directory to every node and run:
```
# in every node
$ cd cluster/ubuntu-cluster
$ sudo ./build.sh
$ sudo cp ./binaries/* /opt/bin
```


> We used flannel here because we want to use overlay network, but please remember it is not the only choice, and it is also not a k8s' necessary dependence. Actually you can just build up k8s cluster natively, or use flannel, Open vSwitch or any other SDN tool you like, we just choose flannel here as a example.

#### II. Configue and install every components upstart script
An example cluster is listed as below:

| IP Address|Role |      
|---------|------|
|10.10.103.223| minion|
|10.10.103.224| minion|
|10.10.103.162| minion|
|10.10.103.250| master|

First of all, make sure `cluster/ubuntu-cluster` exists on this node，and run `configue.sh`.

On master( infra1 10.10.103.250 ) node:

```
# in cluster/ubuntu-cluster
$ sudo ./configure.sh
Welcome to use this script to configure k8s setup

Please enter all your cluster node ips, MASTER node comes first
And separated with blank space like "<ip_1> <ip2> <ip3>": 10.10.103.250 10.10.103.223 10.10.103.224 10.10.103.162

This machine acts as
  both MASTER and MINION:      1
  only MASTER:                 2
  only MINION:                 3
Please choose a role > 2

IP address of this machine > 10.10.103.250

Configure Success
```

On every minion ( e.g.  10.10.103.224 ) node:


```
# in cluster/ubuntu-cluster
$ sudo ./configure.sh 
Welcome to use this script to configure k8s setup

Please enter all your cluster node ips, MASTER node comes first
And separated with blank space like "<ip_1> <ip2> <ip3>": 10.10.103.250 10.10.103.223 10.10.103.224 10.10.103.162

This machine acts as
  both MASTER and MINION:      1
  only MASTER:                 2
  only MINION:                 3
Please choose a role > 3

IP address of this machine > 10.10.103.224

Configure Success
```

If you want a node acts as **both running the master and minion**, please choose option 1.

#### III. Start all components
1. On the master node:
  
	`$ sudo service etcd start`
	
	Then on every minion node:
	
	`$ sudo service etcd start`
	
	> The kubernetes commands will be started automatically after etcd
  
2. On any node:
	
	`$ /opt/bin/etcdctl mk /coreos.com/network/config '{"Network":"10.0.0.0/16"}'`
	
	> You can use the below command on another node to comfirm if the network setting is correct.
	
	> `$ /opt/bin/etcdctl get /coreos.com/network/config`
	
	> If you got `{"Network":"10.0.0.0/16"}`, then etcd cluster is working well.
	> If not , please check` /var/log/upstart/etcd.log` to resolve etcd problem before going forward.
	> Finally, use `ifconfig` to see if there is a new network interface named `flannel0` coming up.
  
  
3. On every minion node
	
	Make sure you have `brctl` installed on every minion, otherwise please run `sudo apt-get install bridge-utils`
	
	`$ sudo ./reconfigureDocker.sh`
	
	This will make the docker daemon aware of flannel network.
 

**All done !**

#### IV. Validation
You can use kubectl command to see if the newly created k8s is working correctly. 

For example , `$ kubectl get minions` to see if you get all your minion nodes comming up. 

Also you can run kubernetes [guest-example](https://github.com/GoogleCloudPlatform/kubernetes/tree/master/examples/guestbook) to build a redis backend cluster on the k8s．

#### V. Trouble Shooting

Generally, what of this guide did is quite simple: 

1. Build and copy binaries and configuration files to proper dirctories on every node

2. Configure `etcd` using IPs based on input from user 

3. Create and start flannel network

So, whenver you have problem, do not blame Kubernetes, **check etcd configuration first** 

Please try:

1. Check `/var/log/upstart/etcd.log` for suspicisous etcd log 

2. Check `/etc/default/etcd`, as we do not have much input validation, a right config should be like:
	```
	ETCD_OPTS="-name infra1 -initial-advertise-peer-urls <http://ip_of_this_node:2380> -listen-peer-urls <http://ip_of_this_node:2380> -initial-cluster-token etcd-cluster-1 -initial-cluster infra1=<http://ip_of_this_node:2380>,infra2=<http://ip_of_another_node:2380>,infra3=<http://ip_of_another_node:2380> -initial-cluster-state new"
	```

3. Remove `data-dir` of etcd and run `reconfigureDocker.sh`again, the default path of `data-dir` is /infra*.etcd/

4. You can also customize your own settings in `/etc/default/{component_name}` after configured success.