Motivation
I have been looking into Kubernetes and wanted to start with defining my own cluster.
Why this blog?
I searched on a lot of ways to implement the k8 clusters. I started out with kubectl. everything went without a hitch until I had to access EBS volumes on AWS. I stumbled into a lot of issues; posting my issues on stackoverflow.com, there was a comment to implement using kops. I searched on installing the cluster using kops and found some of the information available cryptic. I have tried to demystify some of the complexities in using kops.
It is very easy to manage your clusters once you understand the basics of kops
Why my own cluster?
AWS, Google & Azure provide interfaces with Kubernetes - they simplify everything for you very much; while using these services is easy, you miss out on some of the complexities and the understanding that comes with implementing the cluster by yourself.
Versions used
- kops - 1.16.2 (at the time of writing this blog version 1.17 is available)
- kubernetes - 1.18.2
Background
Kops is an utility which enables you to create and maintain Kubernetes clusters. We are using it on AWS and let us launch kops from an EC2 machine.
There are two ways to go about this
- Define an IAM user who has the privileges to create/modify/delete the resources and use this user
- Attach an IAM role with the privileges to create/modify/delete the resources
I am choosing the 2nd option.
Building Blocks
- Create a VPC in region eu-west-1 - Name k8-kops-vpc
Ensure DHCP resolution is enabled and a DHCP option set is associated - Create 3 subnets for zones a,b,c - k8-kops-subnet-1a, k8-ops-subnet-1b, k8-kops-subnet-1c
- Create a private hosted zone shivag.io associate with the VPC k8-lops-vpc
- Create a internet gateway - k8-kops-igw
- Route table k8-kops-rtb
- Route in route table for destination 0.0.0.0/0 to internet gateway k8-kops-igw
- Associate the 3 subnets k8-kops-subnet-1a, k8-ops-subnet-1b, k8-kops-subnet-1c to the route table k8-kops-rtb
- Create a security group associated with VPC k8-kops-sg
- Create inbound rules to enable
- All traffic with your current machine - to do any interaction with the ec2 machines
- All traffic with the security group k8-kops-sg
- Create an S3 bucket k8-kops-cluster-s3
- Create an IAM role k8-kops-role
- Add the following inline policies
- AllowIAM on Resource "*"
"iam:CreateGroup",
"iam:ListRoles",
"iam:ListRolePolicies",
"iam:AttachGroupPolicy",
"iam:CreateUser",
"iam:AddUserToGroup",
"iam:ListInstanceProfiles",
"iam:GetInstanceProfile",
"iam:CreateInstanceProfile",
"iam:GetRole",
"iam:GetRolePolicy",
"iam:PutRolePolicy",
"iam:CreateRole",
"iam:AddRoleToInstanceProfile",
"iam:CreateServiceLinkedRole",
"iam:DeleteRole",
"iam:DeleteInstanceProfile",
"iam:RemoveRoleFromInstanceProfile",
"iam:DeleteRolePolicy",
"iam:PassRole"
- AllowS3 on
Resource
arn:aws:s3:::k8-kops-cluster-s3
arn:aws:s3:::k8-kops-cluster-state-s3
arn:aws:s3:::k8-kops-cluster-s3/*
arn:aws:s3:::k8-kops-cluster-state-s3/*
Actions
"s3:*"
- AllowEc2 on Resource "*"
"ec2:DescribeAvailabilityZones",
"ec2:DescribeKeyPairs",
"ec2:DescribeSecurityGroups",
"ec2:DescribeVolumes",
"ec2:DescribeDhcpOptions",
"ec2:DescribeInternetGateways",
"ec2:DescribeRouteTables",
"ec2:DescribeSubnets",
"ec2:DescribeVpcs",
"ec2:DescribeVpcAttribute",
"ec2:DescribeTags",
"ec2:DescribeImages",
"ec2:DescribeNatGateways",
"ec2:DescribeAddresses",
"ec2:DescribeRegion",
"ec2:CreateVpc",
"ec2:CreateDhcpOptions",
"ec2:CreateRouteTable",
"ec2:CreateRoute",
"ec2:CreateSubnet",
"ec2:CreateSecurityGroup",
"ec2:ModifyVpcAttribute",
"ec2:ImportKeyPair",
"ec2:AssociateDhcpOptions",
"ec2:AuthorizeSecurityGroupEgress",
"ec2:AuthorizeSecurityGroupIngress",
"ec2:CreateVolume",
"ec2:CreateTags",
"ec2:AssociateRouteTable",
"ec2:AllocateAddress",
"ec2:CreateInternetGateway",
"ec2:CreateNatGateway",
"ec2:AttachInternetGateway",
"ec2:AttachVolume",
"ec2:DeleteKeyPair",
"ec2:DeleteDhcpOptions",
"ec2:DeleteRouteTable",
"ec2:DeleteNatGateway",
"ec2:DeleteInternetGateway",
"ec2:RevokeSecurityGroupIngress",
"ec2:RevokeSecurityGroupEgress",
"ec2:DeleteSubnet",
"ec2:DeleteSecurityGroup",
"ec2:DeleteVolume",
"ec2:TerminateInstances",
"ec2:DeleteVpc",
"ec2:DetachInternetGateway",
"ec2:ReleaseAddress"
- AllowAutoscaling on Resource "*"
"autoscaling:DescribeTags",
"autoscaling:DescribeLaunchConfigurations",
"autoscaling:CreateLaunchConfiguration",
"autoscaling:DescribeAutoScalingGroups",
"autoscaling:CreateAutoScalingGroup",
"autoscaling:AttachLoadBalancers",
"autoscaling:EnableMetricsCollection",
"autoscaling:UpdateAutoScalingGroup",
"autoscaling:DeleteAutoscalingGroup",
"autoscaling:DeleteLaunchConfiguration"
- AllowELB on Resource "*"
"elasticloadbalancing:DescribeLoadBalancerAttributes",
"elasticloadbalancing:DescribeLoadBalancers",
"elasticloadbalancing:DescribeTargetGroups"
"elasticloadbalancing:ModifyLoadBalancerAttributes",
"elasticloadbalancing:ConfigureHealthCheck",
"elasticloadbalancing:CreateLoadBalancer",
"elasticloadbalancing:DescribeTags",
"elasticloadbalancing:AddTags",
"elasticloadbalancing:DeleteTags",
"elasticloadbalancing:DeleteLoadBalancer"
- AllowRoute53 on Resource "*"
"route53:GetHostedZone",
"route53:ListHostedZones",
"route53:ListResourceRecordSets",
"route53:ListHostedZonesByName",
"route53:AssociateVPCWithHostedZone",
"route53:ChangeResourceRecordSets"
- Create an EC2 with the following parameters - This ec2 will be the kops instance where you can manage the Kubernetes cluster
- AMI : Ubuntu
- VPC : k8-kops-vpc
- Subnet: any of k8-kops-subnet-1a, k8-ops-subnet-1b, k8-kops-subnet-1c
- Security Group : k8-kops-sg
- IAM : k8-kops-role
- Instance Type : t2.micro
- User Data have the following code
#!/bin/bash
#
# Update the repository and upgrade all the packages
#
apt-get update
apt-get upgrade -y
#
# Install awscli
#
apt-get install -y awscli
#
# Set the aws region variables in the profile for every user logging in
#
echo "***** Set aws default region"
cat > /etc/profile.d/aws-default.sh <export AWS_DEFAULT_REGION=eu-west-1
export AWS_REGION=eu-west-1
EOF
#
# Install packages required
#
apt-get install apt-transport-https
#
# add the pgp key for kubernetes repository
#
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
#
# add the kubernetes repository location
#
cat < /etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF
apt-get update
#
#Install kubectl
#
apt-get install kubectl
#
# Download the latest kops executable
#
curl -LO https://github.com/kubernetes/kops/releases/download/$(curl -s https://api.github.com/repos/kubernetes/kops/releases/latest | grep tag_name | cut -d '"' -f 4)/kops-linux-amd64
chmod +x kops-linux-amd64
#
# Move the latest version to the path
#
sudo mv kops-linux-amd64 /usr/local/bin/kops
Now we have built an EC2 Instance in AWS which has all the permissions and the software that is needed to manage you kubernetes cluster using kops
All we need to do is invoke the kops commands as needed
Following are the parameters we pass for kops
- Name : k8.shivag.io # specifies the name of the cluster
- Zones : eu-west-1a, eu-west-1b, eu-west-1c # indicates the zones the cluster will be having the nodes in
- State : s3://k8-kops-cluster-state-s3 # the s3 bucket where the configuration will be stored
- Kubernetes version : 1.18.2 # version of kubernetes to use
- Networking : calio # the networking that will be used within the pods
- dns-zone : shivag.io # the hosted zone where we will have route 53 entries
- Bastion : "true" # indicates creation of an additional instance where we can login and manage the cluster
Create Cluster
kops create cluster \
--name k8.shivag.io \
--zones eu-west-1a,eu-west-1b,eu-west-1c \
--state s3://k8-kops-cluster-state-s3 \
--kubernetes-version 1.18.2 \
--master-count 1 \
--master-size=t2.medium \
--node-count 3 \
--node-size=t2.micro \
--cloud=aws \
--v=5 \
--networking calico \
--dns-zone=shivag.io \
--topology private \
--bastion="true" \
--dns private
This command creates the configuration on the s3 state folder
Update Cluster
kops update cluster \
--name k8.shivag.io \
--state s3://k8-kops-cluster-state-s3 \
--v=5 \
--yes
This command creates all the resources in AWS
Validate Cluster
kops validate cluster \
--name k8.shivag.io \
--state s3://k8-kops-cluster-state-s3
Delete Cluster
kops delete cluster \
--name k8.shivag.io \
--state s3://k8-kops-cluster-state-s3 \
--yes
This command deletes all the resources and the configuration from s3 state folder
