284 lines
10 KiB
Markdown
284 lines
10 KiB
Markdown
---
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---
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This document describes how to deploy kubernetes on ubuntu nodes, 1 master and 3 nodes involved
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in the given examples. You can scale to **any number of nodes** by changing some settings with ease.
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The original idea was heavily inspired by @jainvipin 's ubuntu single node
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work, which has been merge into this document.
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The scripting referenced here can be used to deploy Kubernetes with
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networking based either on Flannel or on a CNI plugin that you supply.
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This document is focused on the Flannel case. See
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`kubernetes/cluster/ubuntu/config-default.sh` for remarks on how to
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use a CNI plugin instead.
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[Cloud team from Zhejiang University](https://github.com/ZJU-SEL) will maintain this work.
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* TOC
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{:toc}
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## Prerequisites
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1. The nodes have installed docker version 1.2+ and bridge-utils to manipulate linux bridge.
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2. All machines can communicate with each other. Master node needs to be connected to the
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Internet to download the necessary files, while worker nodes do not.
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3. These guide is tested OK on Ubuntu 14.04 LTS 64bit server, but it can not work with
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Ubuntu 15 which uses systemd instead of upstart.
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4. Dependencies of this guide: etcd-2.2.1, flannel-0.5.5, k8s-1.1.8, may work with higher versions.
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5. All the remote servers can be ssh logged in without a password by using key authentication.
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## Starting a Cluster
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### Set up working directory
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Clone the kubernetes github repo locally
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```shell
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$ git clone https://github.com/kubernetes/kubernetes.git
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```
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#### Configure and start the Kubernetes cluster
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The startup process will first download all the required binaries automatically.
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By default etcd version is 2.2.1, flannel version is 0.5.5 and k8s version is 1.1.8.
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You can customize your etcd version, flannel version, k8s version by changing corresponding variables
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`ETCD_VERSION` , `FLANNEL_VERSION` and `KUBE_VERSION` like following.
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```shell
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$ export KUBE_VERSION=1.1.8
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$ export FLANNEL_VERSION=0.5.0
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$ export ETCD_VERSION=2.2.0
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```
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**Note**
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For users who want to bring up a cluster with k8s version v1.1.1, `controller manager` may fail to start
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due to [a known issue](https://github.com/kubernetes/kubernetes/issues/17109). You could raise it
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up manually by using following command on the remote master server. Note that
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you should do this only after `api-server` is up. Moreover this issue is fixed in v1.1.2 and later.
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```shell
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$ sudo service kube-controller-manager start
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```
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Note that we use flannel here to set up overlay network, yet it's optional. Actually you can build up k8s
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cluster natively, or use flannel, Open vSwitch or any other SDN tool you like.
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An example cluster is listed below:
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```shell
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| IP Address | Role |
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|-------------|----------|
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|10.10.103.223| node |
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|10.10.103.162| node |
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|10.10.103.250| both master and node|
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```
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First configure the cluster information in cluster/ubuntu/config-default.sh, following is a simple sample.
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```shell
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export nodes="vcap@10.10.103.250 vcap@10.10.103.162 vcap@10.10.103.223"
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export role="ai i i"
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export NUM_NODES=${NUM_NODES:-3}
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export SERVICE_CLUSTER_IP_RANGE=192.168.3.0/24
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export FLANNEL_NET=172.16.0.0/16
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```
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The first variable `nodes` defines all your cluster nodes, master node comes first and
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separated with blank space like `<user_1@ip_1> <user_2@ip_2> <user_3@ip_3> `
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Then the `role` variable defines the role of above machine in the same order, "ai" stands for machine
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acts as both master and node, "a" stands for master, "i" stands for node.
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The `NUM_NODES` variable defines the total number of nodes.
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The `SERVICE_CLUSTER_IP_RANGE` variable defines the kubernetes service IP range. Please make sure
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that you do have a valid private ip range defined here, because some IaaS provider may reserve private ips.
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You can use below three private network range according to rfc1918. Besides you'd better not choose the one
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that conflicts with your own private network range.
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```shell
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10.0.0.0 - 10.255.255.255 (10/8 prefix)
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172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
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192.168.0.0 - 192.168.255.255 (192.168/16 prefix)
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```
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The `FLANNEL_NET` variable defines the IP range used for flannel overlay network,
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should not conflict with above `SERVICE_CLUSTER_IP_RANGE`.
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You can optionally provide additional Flannel network configuration
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through `FLANNEL_OTHER_NET_CONFIG`, as explained in `cluster/ubuntu/config-default.sh`.
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**Note:** When deploying, master needs to be connected to the Internet to download the necessary files.
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If your machines are located in a private network that need proxy setting to connect the Internet,
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you can set the config `PROXY_SETTING` in cluster/ubuntu/config-default.sh such as:
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PROXY_SETTING="http_proxy=http://server:port https_proxy=https://server:port"
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After all the above variables being set correctly, we can use following command in `cluster/` directory to
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bring up the whole cluster.
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```shell
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$ KUBERNETES_PROVIDER=ubuntu ./kube-up.sh
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```
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The scripts automatically copy binaries and config files to all the machines via `scp` and start kubernetes
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service on them. The only thing you need to do is to type the sudo password when promoted.
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```shell
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Deploying node on machine 10.10.103.223
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...
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[sudo] password to start node:
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```
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If everything works correctly, you will see the following message from console indicating the k8s cluster is up.
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```shell
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Cluster validation succeeded
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```
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### Test it out
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You can use `kubectl` command to check if the newly created cluster is working correctly.
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The `kubectl` binary is under the `cluster/ubuntu/binaries` directory.
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You can make it available via PATH, then you can use the below command smoothly.
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For example, use `$ kubectl get nodes` to see if all of your nodes are ready.
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```shell
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$ kubectl get nodes
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NAME LABELS STATUS
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10.10.103.162 kubernetes.io/hostname=10.10.103.162 Ready
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10.10.103.223 kubernetes.io/hostname=10.10.103.223 Ready
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10.10.103.250 kubernetes.io/hostname=10.10.103.250 Ready
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```
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Also you can run Kubernetes [guest-example](https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/examples/guestbook/) to build a redis backend cluster．
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### Deploy addons
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Assuming you have a starting cluster now, this section will tell you how to deploy addons like DNS
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and UI onto the existing cluster.
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The configuration of DNS is configured in cluster/ubuntu/config-default.sh.
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```shell
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ENABLE_CLUSTER_DNS="${KUBE_ENABLE_CLUSTER_DNS:-true}"
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DNS_SERVER_IP="192.168.3.10"
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DNS_DOMAIN="cluster.local"
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DNS_REPLICAS=1
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```
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The `DNS_SERVER_IP` is defining the ip of dns server which must be in the `SERVICE_CLUSTER_IP_RANGE`.
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The `DNS_REPLICAS` describes how many dns pod running in the cluster.
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By default, we also take care of kube-ui addon.
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```shell
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ENABLE_CLUSTER_UI="${KUBE_ENABLE_CLUSTER_UI:-true}"
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```
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After all the above variables have been set, just type the following command.
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```shell
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$ cd cluster/ubuntu
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$ KUBERNETES_PROVIDER=ubuntu ./deployAddons.sh
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```
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After some time, you can use `$ kubectl get pods --namespace=kube-system` to see the DNS and UI pods are running in the cluster.
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### On going
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We are working on these features which we'd like to let everybody know:
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1. Run kubernetes binaries in Docker using [kube-in-docker](https://github.com/ZJU-SEL/kube-in-docker/tree/baremetal-kube),
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to eliminate OS-distro differences.
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2. Tearing Down scripts: clear and re-create the whole stack by one click.
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### Troubleshooting
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Generally, what this approach does is quite simple:
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1. Download and copy binaries and configuration files to proper directories on every node.
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2. Configure `etcd` for master node using IPs based on input from user.
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3. Create and start flannel network for worker nodes.
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So if you encounter a problem, check etcd configuration of master node first.
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1. Check `/var/log/upstart/etcd.log` for suspicious etcd log
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2. You may find following commands useful, the former one to bring down the cluster, while the latter one could start it again.
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```shell
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$ KUBERNETES_PROVIDER=ubuntu ./kube-down.sh
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$ KUBERNETES_PROVIDER=ubuntu ./kube-up.sh
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```
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3. You can also customize your own settings in `/etc/default/{component_name}` and restart it via
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`$ sudo service {component_name} restart`.
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## Upgrading a Cluster
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If you already have a kubernetes cluster, and want to upgrade to a new version,
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you can use following command in `cluster/` directory to update the whole cluster
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or a specified node to a new version.
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```shell
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$ KUBERNETES_PROVIDER=ubuntu ./kube-push.sh [-m|-n <node id>] <version>
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```
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It can be done for all components (by default), master(`-m`) or specified node(`-n`).
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Upgrading a single node is currently experimental.
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If the version is not specified, the script will try to use local binaries. You should ensure all
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the binaries are well prepared in the expected directory path cluster/ubuntu/binaries.
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```shell
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$ tree cluster/ubuntu/binaries
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binaries/
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├── kubectl
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├── master
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│ ├── etcd
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│ ├── etcdctl
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│ ├── flanneld
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│ ├── kube-apiserver
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│ ├── kube-controller-manager
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│ └── kube-scheduler
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└── minion
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├── flanneld
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├── kubelet
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└── kube-proxy
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```
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You can use following command to get a help.
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```shell
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$ KUBERNETES_PROVIDER=ubuntu ./kube-push.sh -h
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```
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Here are some examples:
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* upgrade master to version 1.0.5: `$ KUBERNETES_PROVIDER=ubuntu ./kube-push.sh -m 1.0.5`
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* upgrade node `vcap@10.10.103.223` to version 1.0.5 : `$ KUBERNETES_PROVIDER=ubuntu ./kube-push.sh -n 10.10.103.223 1.0.5`
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* upgrade master and all nodes to version 1.0.5: `$ KUBERNETES_PROVIDER=ubuntu ./kube-push.sh 1.0.5`
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The script will not delete any resources of your cluster, it just replaces the binaries.
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### Test it out
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You can use the `kubectl` command to check if the newly upgraded kubernetes cluster is working correctly.
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To make sure the version of the upgraded cluster is what you expect, you will find these commands helpful.
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* upgrade all components or master: `$ kubectl version`. Check the *Server Version*.
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* upgrade node `vcap@10.10.102.223`: `$ ssh -t vcap@10.10.102.223 'cd /opt/bin && sudo ./kubelet --version'`
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