kubeinfo

This HTTP service authenticates to the Kubernetes API from an application running inside the Kubernetes cluster and returns metadata about the pods.

Assumptions

• Audience is running a Unix/Linux OS

• Audience has basic knowledge of Go, Docker, Kubernetes, AWS

• All necessary software(s) are installed on audience OS. viz. kubectl, make, Go, Docker

• Respective Paths viz. GOPATH are properly set on audience OS.

• A Kubernetes cluster is running in AWS

• Kubernetes cluster can access public Docker Repo

• Audience following this guide has necessary access to the kube cluster and proper kube-context set.

• The security groups for AWS has ports 30000-32767 open for audience IP Address/Block.

Installation

go get github.com/gudladona87/kubeinfo

Installation on Kubernetes

1. export DOCKER_USER = "gudladona87"

2. docker login --username gudladona87 --password-stdin -- Password provided in the email

3. Install make

4. make deploy

Running tests

> make test

Current code coverage available at ./coverage/coverage.html

Testing the API End to End

For the sake of simplicity the type in .kube/service.yml is set to NodePort, which allows each Node to proxy that port (the same port number on every Node) into the Service.

Once this service is installed on a Kubernetes cluster,

• Grep for the Service kubeinfo. Copy the port the service is exposed on.

  > kubectl get svc | grep kubeinfo
  kubeinfo    NodePort    100.64.219.181  <none> 8080:31046/TCP  27m
  

• Find the pod that the service is running on. Although the same port is exposed on all the nodes, for simplicity I choose to use the node where the pod is running.

  > kubectl get po | grep kube
  kubeinfo-7c854d54d8-vp2tw   1/1 Running   0 30m
  

• Find the Node that the pod is running on

  > kubectl describe pod kubeinfo-7c854d54d8-vp2tw | grep 'Node:'
  Node:           ip-10-75-24-178.ec2.internal/10.75.24.178
  

• Initiate a GET request on the Node and the port at the endpoint /pods

  > curl http://10.75.24.178:31046/pods
  {"pod_count":314,"message":"OK"}
  

Note:

A better approach would be to configure an ingress for the service at a registered domain such as kubeinfo.example.com. But, this requires registering a domain, which I think is out of scope.