2. Infra-as-code (Kubespray)

Deploy DIGIT using Kubespray

Topics covered:

Overview

Kubespray is a composition of Ansible playbooks, inventory, provisioning tools, and domain knowledge for generic OS/Kubernetes cluster configuration management tasks. Kubespray provides:

  • a highly available cluster

  • composable attributes

  • support for most popular Linux distributions

  • continuous-integration tests

Pre-requisites

Before we can get started, we need a few prerequisites to be in place. This is what we are going to need:

  1. A host with Ansible installed. Click here to learn more about Ansible. Find the Ansible installation details here.

  2. You should also set up an SSH key pair to authenticate to the Kubernetes nodes without using a password. This permits Ansible to perform optimally.

  3. Few servers/hosts/VMs to serve as our targets to deploy Kubernetes. I am using Ubuntu 18.04, and my servers each have 4GB RAM and 2vCPUs. This is fine for my testing purposes, which I use to try out new things using Kubernetes. You need to be able to SSH into each of these nodes as root using the SSH key pair I mentioned above.

Deployment Steps

The above will do the following:

  • Create a new Linux User Account for use with Kubernetes on each node

  • Install Kubernetes and containers on each node

  • Configure the Master node

  • Join the Worker nodes to the new cluster

Install Python

Ansible needs Python to be installed on all the machines.

apt-get update && apt-get install python3-pip -y

Disable Swap

sudo swapoff -a
sudo sed -i '/ swap /d' /etc/fstab

Setup SSH using key-based authentication

All the machines should be in the same network with Ubuntu or Centos installed.

ssh key should be generated from the Bastion machine and must be copied to all the servers part of your inventory.

  • Generate the ssh key ssh-keygen -t rsa

  • Copy over the public key to all nodes.

    ssh-copy-id root@<node-ip-address>

Setup Ansible Controller Machine Setup Kubespray

  • Clone the official repository

git clone https://github.com/kubernetes-incubator/kubespray.git
cd kubespray

  • Install dependencies from requirements.txt

sudo pip install -r requirements.txt

  • Create Inventory

cp -rfp inventory/sample inventory/mycluster

where mycluster is the custom configuration name. Replace with whatever name you would like to assign to the current cluster.

Create inventory using an inventory generator.

declare -a IPS=(10.67.53.158 10.67.53.159 10.67.53.160 10.67.53.161 10.67.53.162 10.67.53.163 10.67.53.164)
CONFIG_FILE=inventory/mycluster/hosts.yaml python3 contrib/inventory_builder/inventory.py ${IPS[@]}

Once it runs, you can see an inventory file that looks like the below:

all:
  hosts:
    node1:
      ansible_host: 10.67.53.158
      ip: 10.67.53.158
      access_ip: 10.67.53.158
    node2:
      ansible_host: 10.67.53.159
      ip: 10.67.53.159
      access_ip: 10.67.53.159
    node3:
      ansible_host: 10.67.53.160
      ip: 10.67.53.160
      access_ip: 10.67.53.160
    node4:
      ansible_host: 10.67.53.161
      ip: 10.67.53.161
      access_ip: 10.67.53.161
    node5:
      ansible_host: 10.67.53.162
      ip: 10.67.53.162
      access_ip: 10.67.53.162
    node6:
      ansible_host: 10.67.53.163
      ip: 10.67.53.163
      access_ip: 10.67.53.163
   node7:
      ansible_host: 10.67.53.164
      ip: 10.67.53.164
      access_ip: 10.67.53.164    
  children:
    kube-master:
      hosts:
        node1:
        node2:
        node3:
    kube-node:
      hosts:
        node1:
        node2:
        node3:
        node4:
        node5:
        node6:
        node7:
    etcd:
      hosts:
        node1:
        node2:
        node3:
        node4:
    k8s-cluster:
      children:
        kube-master:
        kube-node:
    calico-rr:
      hosts: {}

  • Review and change parameters under inventory/mycluster/group_vars

vim inventory/mycluster/group_vars/all/all.yml
...
## External LB example config
## apiserver_loadbalancer_domain_name: "elb.some.domain"
apiserver_loadbalancer_domain_name: "10.211.55.101"
loadbalancer_apiserver:
  address: 10.211.55.101
  port: 443

Deploy Kubespray with Ansible Playbook - run the playbook as Ubuntu

  • The option --become is required for example writing SSL keys in /etc/, installing packages and interacting with various system daemons.

  • Note: Without --become - the playbook will fail to run!

ansible-playbook -i inventory/mycluster/hosts.yaml  --become --become-user=ubuntu cluster.yml

Kubernetes cluster will be created with three masters and four nodes using the above process.

Kube config will be generated in a .Kubefolder. The cluster can be accessible via kubeconfig.

HA-Proxy

  • Install haproxy package in a haproxy machine that will be allocated for proxy

sudo apt-get install haproxy -y

  • IPs need to be whitelisted as per the requirements in the config.

sudo vim /etc/haproxy/haproxy.cfg

global
	log /dev/log	local0
	log /dev/log	local1 notice
	chroot /var/lib/haproxy
	stats socket /run/haproxy/admin.sock mode 660 level admin expose-fd listeners
	stats timeout 30s
	user haproxy
	group haproxy
	daemon

	# Default SSL material locations
       # ca-base /etc/ssl/certs
      #	crt-base /etc/ssl/private

	# Default ciphers to use on SSL-enabled listening sockets.
	# For more information, see ciphers(1SSL). This list is from:
	#  https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
	# An alternative list with additional directives can be obtained from
	#  https://mozilla.github.io/server-side-tls/ssl-config-generator/?server=haproxy
	#ssl-default-bind-ciphers 
	#ssl-default-bind-options no-sslv3

defaults
	log	global
	mode	http
	option	httplog
	option	dontlognull
            timeout connect 5000
            timeout check   5000
            timeout client  30000
             timeout server  60000

frontend http-in
    bind *:80
    mode tcp
    default_backend http-servers
    http-request redirect scheme https unless { ssl_fc }

frontend https-in
    bind *:443
    mode tcp
    default_backend https-servers

frontend kube-in
    bind *:8383
    mode tcp
    timeout client 3h
    #Jenkins_CD eGov_ACT eGov_Spectra 
    #acl network_allowed src 35.244.58.192 106.51.69.20 180.151.198.122 103.122.14.159 35.154.77.83 35.154.203.141 125.16.100.118 10.67.53.252  52.71.194.45 132.154.83.214 27.6.189.204 10.67.53.120
    #tcp-request connection reject if !network_allowed
    default_backend kube-servers

frontend kube2-in
    bind *:6363
    mode tcp
    timeout client 3h
    #Jenkins_CD eGov_ACT eGov_Spectra
    acl network_allowed src 35.244.58.192 106.51.69.20 180.151.198.122 103.122.14.159 35.154.77.83 35.154.203.141 125.16.100.118 10.67.53.252  52.71.194.45 132.154.83.214 27.6.189.204 10.67.53.120
    tcp-request connection reject if !network_allowed
    default_backend kube-servers


backend http-servers
        mode tcp
        balance roundrobin
        server srv4 10.67.53.161:32080 send-proxy
        server srv5 10.67.53.162:32080 send-proxy
        server srv6 10.67.53.163:32080 send-proxy

backend https-servers
        mode tcp
        balance roundrobin
        server srv4 10.67.53.161:32443 send-proxy
        server srv5 10.67.53.162:32443 send-proxy
        server srv6 10.67.53.163:32443 send-proxy

backend kube-servers
        mode tcp     
        option log-health-checks
        timeout server 3h
        server master1 10.67.53.158:6443 check check-ssl verify none inter 10000
        server master2 10.67.53.159:6443 check check-ssl verify none inter 10000
        server master3 10.67.53.160:6443 check check-ssl verify none inter 10003
        balance roundrobin

Volumes

Iscsi volumes will be provided by the SDC team as per the requisition and the same can be used for statefulsets.

sudo iscsiadm -m discovery -t sendtargets -p 10.67.49.8:3260

Note: Please refer to the DIGIT deployment documentation to deploy DIGIT services.

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