zhming0 / k8s-eip

Bind Elastic IPs to Kubernetes nodes on AWS to reduce cost.

K8S-EIP

Bind a group of AWS Elastic IPs to a group of Kubernetes Nodes that matches criteria.

Huh? What is this?

Q: What is k8s-eip trying to solve?

I don't want to create many unnecessary ELBs just for my toy cluster created by kops.

Q: Can't you just use nginx-ingress so you just create one ELB for many services?

Nah, I don't want to pay that $18/month either. I don't want any ELB.

Q: What a miser! But how?

k8s-eip for you. It's similar to the kube-ip but for AWS and less mature. It would bind a group of specified Elastic IPs to a number of K8S nodes on AWS. It runs in a periodic way, so you can't use it for HA/critical use cases.

Q: Would it trigger the scary Elastic IP remap fee?

As a project with a goal of saving money, surely no :). Actually, it will try not to.

How to use it?

Prerequisite

• You are an admin of k8s cluster on AWS and you have kubectl configured properly. Quick test: kubectl cluster-info
• You have credentials for an IAM user with following permission:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ec2:AssociateAddress"
            ],
            "Resource": "*"
        }
    ]
}

• You have labeled the targetted nodes

Via: kubectl

kubectl label node YOUR_NODE_NAME bastion=true

Via: kops

---
...
kind: InstanceGroup
...
spec:
  ...
  nodeLabels:
    ...
    bastion: "true" # Or anything you want
  ...

Using Helm v3

First, Prepare a yaml file like this:

awsAccessKeyId:  "XXXXXXX" # AWS_ACCESS_KEY_ID of the IAM user account
awsSecretAccessKey: "XXXXXXXXXXXXXXXX" # secret access key of the IAM user account
awsRegion: us-east-1

# Elastic IPs that you own and want to attach to targeting nodes
ips: "8.8.8.8,1.1.1.1"  # example
# The label on Nodes that you want to have elastic IPs attached
labelSelector: "bastion=true" # example

Then

helm upgrade -i \
  -f values.yaml \ # The yaml file that you prepared
  -n kube-system \ # This could be any namespace, kube-system is a good idea
  k8s-eip \ # any name
  https://github.com/zhming0/k8s-eip/releases/download/v0.0.1/k8s-eip-0.0.1.tgz

Note:

• Helm is flexible. There are many ways to supply values. Please refer to their doc for other options.
• use --dry-run to preview the changes

Using Helm v2

Nope :)

Kubectl directly

Good luck :)

Project status

As you can see, this is early stage and not actively maintained as I don't believe it create much value. Any help is still appreciated though. Some potential work could be:

• Use K8S's watch API to replace/enhance periodic run
• Improve determinism, reduce unnecessary Elastic IPs mapping even when there are many changes happening to k8s nodes.