Skip to content

HiteshRepo/load-balancer

BranchesTags

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

11 Commits
build
build
 
 
cmd
cmd
 
 
internal
internal
 
 
.gitignore
.gitignore
 
 
README.md
README.md
 
 
Taskfile.yaml
Taskfile.yaml
 
 
go.mod
go.mod
 
 
go.sum
go.sum
 
 

Repository files navigation

Steps for the setup

Simple REST app

The below app just gives out its own pod name in response on a GET call to its '/' endpoint.

  1. Install task cli tool:
go install github.com/go-task/task/v3/cmd/task@latest
  1. cd into root directory:
cd ../load-balancer
  1. compile, package and publish restSimpleApp:
task compile-restSimpleApp

task package-restSimpleApp

task publish-restSimpleApp

Note: skip steps #1, #2 and #3 since, the app's image has already been pushed to dockerhub.

  1. Setup a kubernetes cluster, easier way to do this is via minikube: https://kubernetes.io/docs/tutorials/hello-minikube/

  2. Deploy the app

kubectl create -f build/restSimpleApp/deploy.yaml
  1. Get the pods
kubectl get po -l app=rest-simple-app -o wide

NAME                               READY   STATUS    RESTARTS   AGE   IP           NODE                              NOMINATED NODE   READINESS GATES
rest-simple-app-6c9dc776f5-gwnvq   2/2     Running   0          59s   10.244.0.4   eksabm-testbed1-core-dev-node-0   <none>           <none>
rest-simple-app-6c9dc776f5-hkp7w   2/2     Running   0          59s   10.244.0.2   eksabm-testbed1-core-dev-node-0   <none>           <none>
rest-simple-app-6c9dc776f5-vfnbx   2/2     Running   0          59s   10.244.0.3   eksabm-testbed1-core-dev-node-0   <none>           <none>
  1. Curl the pods using their IP and listening router port
curl 10.244.0.4:9090 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-gwnvq

curl 10.244.0.3:9090 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-vfnbx

curl 10.244.0.2:9090 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-hkp7w

Proxy app

This app is designed to act as a proxy for any number of urls.

  1. compile, package and publish proxyApp:
task compile-proxyApp

task package-proxyApp

task publish-proxyApp

Note: skip steps #1 since, the app's image has already been pushed to dockerhub.

  1. Deploy the proxy app
kubectl create -f build/proxyApp/deploy.yaml

kubectl get po -o wide -l app=proxy-app

NAME                         READY   STATUS    RESTARTS   AGE    IP             NODE                              NOMINATED NODE   READINESS GATES
proxy-app-6c6bd559d7-rx7m2   2/2     Running   0          3m4s   10.244.0.254   eksabm-testbed1-core-dev-node-0   <none>           <none>
  1. Deploy the proxy svc
kubectl create -f build/proxyApp/svc.yaml

kubectl get svc

NAME                       TYPE           CLUSTER-IP       EXTERNAL-IP                                   PORT(S)                               AGE
proxy-svc                  ClusterIP      10.108.215.193   <none>                                        9092/TCP                              3m52s
  1. Request to add all pod-urls to the proxy
curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.4:9090"}' -w "\n"
proxy registered

curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.2:9090"}' -w "\n"
proxy registered

curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.3:9090"}' -w "\n"
proxy registered
  1. Request to serve proxy
curl 10.108.215.193:9092 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-gwnvq

curl 10.108.215.193:9092 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-gwnvq

Note: does not matter how many times you hit the proxy, request is redirected to same po [the first one all the time]. Can you spot the issue in the code in the branch 'setup-proxy'? What we have achieved though is to setup a proxy that redirects the request to the pod(s) behind it. Now we would like to move on to achieve load balancing!!

  1. Before we move on to load balancing, lets setup periodic health check of the urls we add behind our proxy

the proxy app's image 'hiteshpattanayak/proxy-app:2.0' has the health check feature setup. Also the image has been updated in 'proxyApp-deploy.yaml'.

Deploy the latest proxy app

kubectl apply -f build/proxyApp/deploy.yaml

deployment.apps/proxy-app configured

kubectl get po -l app=proxy-app

NAME                        READY   STATUS    RESTARTS   AGE
proxy-app-6c6bd559d7-rx7m2   2/2     Running   0          29s
  1. Repeat the 'addUrl' requests again
curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.4:9090"}' -w "\n"
proxy registered

curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.3:9090"}' -w "\n"
proxy registered

curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.2:9090"}' -w "\n"
proxy registered

## adding an invalid url
curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://1.2.3.4:9090"}' -w "\n"
proxy registered
  1. check logs of the proxy app pod
kubectl logs -f proxy-app-555465b5b-xwz42 -c proxy-app

[GIN] 2023/04/16 - 12:33:08 | 200 |     420.363µs |       127.0.0.1 | POST     "/addurl"
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
[GIN] 2023/04/16 - 12:33:14 | 200 |    1.198732ms |       127.0.0.1 | POST     "/addurl"
16047-09+00 47:23:23 -> url(http://10.244.0.4:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.2:9090) is available.
[GIN] 2023/04/16 - 12:33:19 | 200 |     292.743µs |       127.0.0.1 | POST     "/addurl"
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
16047-09+00 47:23:23 -> url(http://1.2.3.4:9090) is unavailable.
[GIN] 2023/04/16 - 12:33:25 | 200 |     337.648µs |       127.0.0.1 | POST     "/addurl"
16047-09+00 47:23:23 -> url(http://10.244.0.4:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.2:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
16047-09+00 47:23:23 -> url(http://1.2.3.4:9090) is unavailable.
16047-09+00 47:23:23 -> url(http://10.244.0.4:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.2:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
16047-09+00 47:23:23 -> url(http://1.2.3.4:9090) is unavailable.
16047-09+00 47:23:23 -> url(http://10.244.0.4:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.2:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
16047-09+00 47:23:23 -> url(http://1.2.3.4:9090) is unavailable.
16047-09+00 47:23:23 -> url(http://10.244.0.4:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.2:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
16047-09+00 47:23:23 -> url(http://1.2.3.4:9090) is unavailable.
16047-09+00 47:23:23 -> url(http://10.244.0.4:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.2:9090) is available.
16047-09+00 47:23:23 -> url(http://10.244.0.3:9090) is available.
16047-09+00 47:23:23 -> url(http://1.2.3.4:9090) is unavailable.

  1. Lets deploy hiteshpattanayak/proxy-app:3.0 which contains implementation of round robin load balancing strategy.

  2. Deploy the latest proxy app

kubectl apply -f build/proxyApp/deploy.yaml

deployment.apps/proxy-app configured
  1. Repeat the 'addUrl' requests again, we do this because we do not have a persistent stirage as yet. All the urls are stored in-memory.
curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.4:9090"}' -w "\n"
proxy registered

curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.3:9090"}' -w "\n"
proxy registered

curl 10.108.215.193:9092/addurl --header "Content-Type: application/json" --request "POST" --data '{"url": "http://10.244.0.2:9090"}' -w "\n"
proxy registered
  1. Request to serve proxy now
curl 10.108.215.193:9092 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-vfnbx

curl 10.108.215.193:9092 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-hkp7w

curl 10.108.215.193:9092 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-gwnvq

curl 10.108.215.193:9092 -w "\n"
responding from a simple rest app with pod name: rest-simple-app-6c9dc776f5-vfnbx

Note: The load balancer redirects requests across pods in a round-robin manner.

What if we could redirect requests in a weighted fashion? Could set an url's (server's) capability to handle more requests/load and the load balancer could redirect request based on that? Lets find out in the next steps.

About

No description, website, or topics provided.

Resources

Readme
Activity

Stars

0 stars

Watchers

1 watching

Forks

0 forks
Report repository

Releases

3 tags

Packages

No packages published

Languages