204 lines
6.6 KiB
Markdown
204 lines
6.6 KiB
Markdown
kubernetes-ansible
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========
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Install and configure a kubernetes cluster including network overlay and optionnal addons.
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Based on [CiscoCloud](https://github.com/CiscoCloud/kubernetes-ansible) work.
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### Requirements
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Tested on **Debian Jessie** and **Ubuntu** (14.10, 15.04, 15.10).
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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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Ansible v1.9.x
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### Components
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* [kubernetes](https://github.com/kubernetes/kubernetes/releases) v1.0.6
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* [etcd](https://github.com/coreos/etcd/releases) v2.2.0
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* [calicoctl](https://github.com/projectcalico/calico-docker/releases) v0.5.1
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* [flanneld](https://github.com/coreos/flannel/releases) v0.5.3
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* [docker](https://www.docker.com/) v1.8.2
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Ansible
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-------------------------
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### Download binaries
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A role allows to download required binaries which will be stored in a directory defined by the variable
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**'local_release_dir'** (by default /tmp).
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Please ensure that you have enough disk space there (about **1G**).
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**Note**: Whenever you'll need to change the version of a software, you'll have to erase the content of this directory.
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### Variables
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The main variables to change are located in the directory ```environments/[env_name]/group_vars/k8s-cluster.yml```.
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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: etcd, tags: etcd }
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- { role: docker, tags: docker }
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- { role: overlay_network, tags: ['calico', 'flannel', 'network'] }
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- { role: dnsmasq, tags: dnsmasq }
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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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- { role: apps/k8s-skydns, tags: ['skydns', 'apps'] }
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- { role: apps/k8s-fabric8, tags: ['fabric8', 'apps'] }
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- hosts: kube-node
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roles:
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- { role: kubernetes/node, tags: node }
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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 environments/dev/inventory cluster.yml -u root
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```
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Kubernetes
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-------------------------
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### Network Overlay
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You can choose between 2 network overlays. 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 '**overlay_network_plugin**'
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### Expose a service
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There are several loadbalancing solutions.
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The ones 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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Master processes : kube-apiserver, kube-scheduler, kube-controller, kube-proxy
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Nodes processes : kubelet, kube-proxy, [calico-node|flanneld]
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* Check the status of the processes
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```
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systemctl status [process_name]
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```
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* Check the logs
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```
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journalctl -ae -u [process_name]
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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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#### Available apps, installation procedure
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Additionnal apps can be installed with ```ansible-galaxy```.
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you'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 if you will probably want to install a [dns server](https://github.com/kubernetes/kubernetes/tree/master/cluster/addons/dns) as it is **strongly recommanded**.
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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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```
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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-skydns.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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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 your playbook with the chosen role, 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: kubernetes/master, tags: master }
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- { role: apps/k8s-skydns, tags: ['skydns', 'apps'] }
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...
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```
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Please refer to the [k8s-skydns readme](https://github.com/ansibl8s/k8s-skydns) for additionnal info.
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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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Congrats ! now you can walk through [kubernetes basics](http://kubernetes.io/v1.0/basicstutorials.html)
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Known issues
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-------------
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### Node reboot and Calico
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There is a major issue with calico-kubernetes version 0.5.1 and kubernetes prior to 1.1 :
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After host reboot, the pods networking are not configured again, they are started without any network configuration.
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This issue will be fixed when kubernetes 1.1 will be released as described in this [issue](https://github.com/projectcalico/calico-kubernetes/issues/34)
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### Monitoring addon
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Until now i didn't managed to get the monitoring addon working.
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### Apiserver listen on secure port only
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Currently the api-server listens on both secure and insecure ports.
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The insecure port is mainly used for calico.
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Will be fixed soon.
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How to contribute
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------------------
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### Update available roles
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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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You can list available submodules with the following command:
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```
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grep path .gitmodules | sed 's/.*= //'
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```
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For instance if you will probably want to install a [dns server](https://github.com/kubernetes/kubernetes/tree/master/cluster/addons/dns) as it is **strongly recommanded**.
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In order to use this role you'll need to follow these steps
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```
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git submodule init roles/apps/k8s-common roles/apps/k8s-skydns
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git submodule update
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```
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