328 lines
9.6 KiB
Markdown
328 lines
9.6 KiB
Markdown
[](https://travis-ci.org/ansibl8s/setup-kubernetes)
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kubernetes-ansible
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========
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This project allows to
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- Install and configure a **Multi-Master/HA kubernetes** cluster.
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- Choose the **network plugin** to be used within the cluster
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- A **set of roles** in order to install applications over the k8s cluster
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- A **flexible method** which helps to create new roles for apps.
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Linux distributions tested:
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* **Debian** Wheezy, Jessie
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* **Ubuntu** 14.10, 15.04, 15.10
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* **Fedora** 23
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* **CentOS** 7 (Currently with flannel only)
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### Requirements
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* The target servers must have **access to the Internet** in order to pull docker imaqes.
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* The firewalls are not managed, you'll need to implement your own rules the way you used to.
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in order to avoid any issue during deployment you should **disable your firewall**
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* **Copy your ssh keys** to all the servers part of your inventory.
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* **Ansible v1.9.x/v2.x and python-netaddr**
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* Base knowledge on Ansible. Please refer to [Ansible documentation](http://www.ansible.com/how-ansible-works)
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### Components
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* [kubernetes](https://github.com/kubernetes/kubernetes/releases) v1.1.4
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* [etcd](https://github.com/coreos/etcd/releases) v2.2.2
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* [calicoctl](https://github.com/projectcalico/calico-docker/releases) v0.14.0
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* [flanneld](https://github.com/coreos/flannel/releases) v0.5.5
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* [docker](https://www.docker.com/) v1.9.1
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Quickstart
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-------------------------
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The following steps will quickly setup a kubernetes cluster with default configuration.
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These defaults are good for tests purposes.
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Edit the inventory according to the number of servers
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```
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[downloader]
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localhost ansible_connection=local ansible_python_interpreter=python2
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[kube-master]
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10.115.99.31
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[etcd]
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10.115.99.31
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10.115.99.32
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10.115.99.33
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[kube-node]
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10.115.99.32
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10.115.99.33
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[k8s-cluster:children]
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kube-node
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kube-master
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```
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Run the playbook
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```
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ansible-playbook -i inventory/inventory.cfg cluster.yml -u root
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```
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You can jump directly to "*Available apps, installation procedure*"
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Ansible
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-------------------------
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### Variables
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The main variables to change are located in the directory ```inventory/group_vars/all.yml```.
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### Inventory
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Below is an example of an inventory.
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Note : The bgp vars local_as and peers are not mandatory if the var **'peer_with_router'** is set to false
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By default this variable is set to false and therefore all the nodes are configure in **'node-mesh'** mode.
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In node-mesh mode the nodes peers with all the nodes in order to exchange routes.
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```
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[downloader]
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localhost ansible_connection=local ansible_python_interpreter=python2
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[kube-master]
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node1 ansible_ssh_host=10.99.0.26
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node2 ansible_ssh_host=10.99.0.27
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[etcd]
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node1 ansible_ssh_host=10.99.0.26
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node2 ansible_ssh_host=10.99.0.27
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node3 ansible_ssh_host=10.99.0.4
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[kube-node]
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node2 ansible_ssh_host=10.99.0.27
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node3 ansible_ssh_host=10.99.0.4
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node4 ansible_ssh_host=10.99.0.5
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node5 ansible_ssh_host=10.99.0.36
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node6 ansible_ssh_host=10.99.0.37
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[paris]
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node1 ansible_ssh_host=10.99.0.26
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node3 ansible_ssh_host=10.99.0.4 local_as=xxxxxxxx
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node4 ansible_ssh_host=10.99.0.5 local_as=xxxxxxxx
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[new-york]
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node2 ansible_ssh_host=10.99.0.27
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node5 ansible_ssh_host=10.99.0.36 local_as=xxxxxxxx
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node6 ansible_ssh_host=10.99.0.37 local_as=xxxxxxxx
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[k8s-cluster:children]
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kube-node
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kube-master
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```
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### Playbook
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```
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---
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- hosts: downloader
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sudo: no
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roles:
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- { role: download, tags: download }
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- hosts: k8s-cluster
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roles:
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- { role: kubernetes/preinstall, tags: preinstall }
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- { role: docker, tags: docker }
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- { role: kubernetes/node, tags: node }
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- { role: etcd, tags: etcd }
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- { role: dnsmasq, tags: dnsmasq }
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- { role: network_plugin, tags: ['calico', 'flannel', 'network'] }
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- hosts: kube-master
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roles:
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- { role: kubernetes/master, tags: master }
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```
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### Run
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It is possible to define variables for different environments.
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For instance, in order to deploy the cluster on 'dev' environment run the following command.
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```
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ansible-playbook -i inventory/dev/inventory.cfg cluster.yml -u root
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```
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Kubernetes
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-------------------------
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### Multi master notes
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* 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 ...),
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the server address has to be present on both groups 'kube-master' and 'kube-node'.
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* Almost all kubernetes components are running into pods except *kubelet*. These pods are managed by kubelet which ensure they're always running
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* For safety reasons, you should have at least two master nodes and 3 etcd servers
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* 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.
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In order to do so, some variables have to be used '**loadbalancer_apiserver**' and '**apiserver_loadbalancer_domain_name**'
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### Network Overlay
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You can choose between 2 network plugins. Only one must be chosen.
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* **flannel**: gre/vxlan (layer 2) networking. ([official docs](https://github.com/coreos/flannel))
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* **calico**: bgp (layer 3) networking. ([official docs](http://docs.projectcalico.org/en/0.13/))
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The choice is defined with the variable '**kube_network_plugin**'
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### Expose a service
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There are several loadbalancing solutions.
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The one i found suitable for kubernetes are [Vulcand](http://vulcand.io/) and [Haproxy](http://www.haproxy.org/)
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My cluster is working with haproxy and kubernetes services are configured with the loadbalancing type '**nodePort**'.
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eg: each node opens the same tcp port and forwards the traffic to the target pod wherever it is located.
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Then Haproxy can be configured to request kubernetes's api in order to loadbalance on the proper tcp port on the nodes.
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Please refer to the proper kubernetes documentation on [Services](https://github.com/kubernetes/kubernetes/blob/release-1.0/docs/user-guide/services.md)
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### Check cluster status
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#### Kubernetes components
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* Check the status of the processes
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```
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systemctl status kubelet
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```
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* Check the logs
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```
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journalctl -ae -u kubelet
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```
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* Check the NAT rules
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```
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iptables -nLv -t nat
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```
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For the master nodes you'll have to see the docker logs for the apiserver
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```
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docker logs [apiserver docker id]
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```
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### Available apps, installation procedure
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There are two ways of installing new apps
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#### Ansible galaxy
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Additionnal apps can be installed with ```ansible-galaxy```.
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ou'll need to edit the file '*requirements.yml*' in order to chose needed apps.
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The list of available apps are available [there](https://github.com/ansibl8s)
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For instance it is **strongly recommanded** to install a dns server which resolves kubernetes service names.
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In order to use this role you'll need the following entries in the file '*requirements.yml*'
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Please refer to the [k8s-kubedns readme](https://github.com/ansibl8s/k8s-kubedns) for additionnal info.
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```
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- src: https://github.com/ansibl8s/k8s-common.git
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path: roles/apps
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# version: v1.0
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- src: https://github.com/ansibl8s/k8s-kubedns.git
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path: roles/apps
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# version: v1.0
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```
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**Note**: the role common is required by all the apps and provides the tasks and libraries needed.
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And empty the apps directory
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```
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rm -rf roles/apps/*
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```
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Then download the roles with ansible-galaxy
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```
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ansible-galaxy install -r requirements.yml
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```
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Finally update the playbook ```apps.yml``` with the chosen roles, and run it
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```
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...
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- hosts: kube-master
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roles:
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- { role: apps/k8s-kubedns, tags: ['kubedns', 'apps'] }
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...
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```
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```
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ansible-playbook -i inventory/inventory.cfg apps.yml -u root
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```
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#### Git submodules
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Alternatively the roles can be installed as git submodules.
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That way is easier if you want to do some changes and commit them.
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### Networking
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#### Calico networking
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Check if the calico-node container is running
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```
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docker ps | grep calico
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```
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The **calicoctl** command allows to check the status of the network workloads.
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* Check the status of Calico nodes
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```
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calicoctl status
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```
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* Show the configured network subnet for containers
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```
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calicoctl pool show
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```
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* Show the workloads (ip addresses of containers and their located)
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```
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calicoctl endpoint show --detail
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```
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#### Flannel networking
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* Flannel configuration file should have been created there
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```
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cat /run/flannel/subnet.env
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FLANNEL_NETWORK=10.233.0.0/18
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FLANNEL_SUBNET=10.233.16.1/24
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FLANNEL_MTU=1450
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FLANNEL_IPMASQ=false
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```
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* Check if the network interface has been created
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```
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ip a show dev flannel.1
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4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default
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link/ether e2:f3:a7:0f:bf:cb brd ff:ff:ff:ff:ff:ff
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inet 10.233.16.0/18 scope global flannel.1
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valid_lft forever preferred_lft forever
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inet6 fe80::e0f3:a7ff:fe0f:bfcb/64 scope link
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valid_lft forever preferred_lft forever
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```
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* Docker must be configured with a bridge ip in the flannel subnet.
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```
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ps aux | grep docker
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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
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```
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* Try to run a container and check its ip address
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```
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kubectl run test --image=busybox --command -- tail -f /dev/null
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replicationcontroller "test" created
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kubectl describe po test-34ozs | grep ^IP
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IP: 10.233.16.2
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```
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```
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kubectl exec test-34ozs -- ip a show dev eth0
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8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1450 qdisc noqueue
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link/ether 02:42:0a:e9:2b:03 brd ff:ff:ff:ff:ff:ff
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inet 10.233.16.2/24 scope global eth0
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valid_lft forever preferred_lft forever
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inet6 fe80::42:aff:fee9:2b03/64 scope link tentative flags 08
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valid_lft forever preferred_lft forever
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```
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Congrats ! now you can walk through [kubernetes basics](http://kubernetes.io/v1.1/basicstutorials.html)
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