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Ansible Playbooks To setup cross-datacenters Kubernetes HA (multi-master) on Redhat Enterprise Linux 7.

This repository provides Ansible Playbooks To setup Kubernetes HA on Redhat Enterprise Linux 7. The playbooks are mainly inspired by Kubeadm documentation and other ansible tentatives on github. The playbooks could be used separately or as one playbook for a fully fledged HA cluster.

Prerequisites:

RHEL 7.2+ On your manager machine install python pip:

wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh epel-release-latest-7.noarch.rpm
yum install python-pip

Install ansible on your ansible manager machine.

  • You can do:
pip install ansible
  • Setup ssh access from master to workers. ssh-copy-id -i ~/.ssh/id_rsa.pub <user@host>

Environment preparation:

  • Clone the repo: In the machine that you want to use as ansible manager (can be your laptop or any other machine that has ssh access to the target machines):
git clone [email protected]:IBM/ansible-kubernetes-ha-cluster.git
cd ansible-k8s-ha
  • Create inventory/mycluster and declare your machines such as:
myhostname.domain.com ansible_usehost=<ip>

Also make sure to update the vars section:

  • choose the desired versions for kubernetes and docker
  • setup the pod network cidr (default setup is for flannel)
  • Setup the eviction hard properties for workers and masters
  • Choose whether you want to use a private setup or a public one, with a private setup, you need to provide the credentials to get the yum packages and docker images.
  • Specify the network zone for firewalld setup (default is public)

There are different groups being defined and used, you can reuse mycluster file defined in inventory folder:

[dc1-k8s-masters] # these are all the masters of datacenter 1 (DC1)
[dc1-k8s-workers-vm] # these are all the VM worker nodes of DC1
[dc1-k8s-workers-bm] # these are all baremetal worker nodes of DC1

We can have as many data centers as we need. For each data center, define the masters and workers and add them to [k8s-masters:children], [k8s-workers:children], and [k8s-nodes:children].

You can check that you can ping all the machines:

ansible -m ping all -i inventory/mycluster

Install a highly available kubernetes using kubeadm

You can now run k8s-all playbook to get your cluster setup. You can also run the different playbooks separately for different purposes (setting up docker, etcd, keepalived, kubeadm ...).

ansible-playbook -i inventory/mycluster  playbooks/k8s-all.yaml

What k8s-all.yaml includes:

  • Adding the required yum repository (private or public)
  • Installing ntpd
  • Installing docker
  • Installing kubeadm, kubelet and kubectl
  • Setting up the firewalld
  • Generating etcd certificates and installing ha etcd cluster on all the master nodes
  • Installing haproxy
  • Installing keepalived and setting up vip management (this optional, use only when you have a vip)
  • Setting up kubernetes masters
  • Adding the nodes to the cluster
  • Reconfiguring the nodes and components to communicate through haproxy
  • Encrypting kubernetes secrets at rest
  • Adding heapster
  • Running a smoke test

Restarting the install:

If you need to restart the process using kubeadm reset, please use the cleanup-all-vms playbook that deletes the state from all vms. Some of the commands might fail but you can ignore that.

Encrypting Secrets at rest (already in the k8s-all playbook):

If you want to add an extra layer of securing your secrets by encrypting them at rest you can use the "encrypting-secrets.yaml playbook". You can add it to the k8s-all.yaml or use it separately.

Before using it, update the inventory file to change the encryption key variable "encoded_secret". To generate a new encryption key you can do the following:

head -c 32 /dev/urandom | base64

Copy the output and save it in the inventory variable.

After that run the playbook:

ansible-playbook -i inventory/mycluster  playbooks/encrypting-secrets.yaml

Work in progress:

We will add the following items to this repository:

  • Kubeadm upgrade playbook
  • Adding the possibility of using other user then root
  • Addons, Prometheus support?

Contribution:

In order to contribute please feel free to create github issues and PRs.