added DEVELOPMENT.md with a local setup (#64)

* added DEVELOPMENT.md with a local setup

* remove extra code

* removed concepts.md

* added a document for integration with keda

* removed prom stack values

DEVELOPMENT.md

@@ -0,0 +1,250 @@
+# Development Guide
+
+Setting up your development environment for Elasti involves preparing your local setup for building, testing, and contributing to the project. Follow these steps to get started:
+
+## Dev Environment
+
+### 1. Get required tools
+
+Ensure you have the following tools installed:
+
+- **Go:** The programming language used for Elasti. Download and install it from [golang.org](https://golang.org/dl/).
+- **Docker:** For containerization and building Docker images. Install it from [docker.com](https://www.docker.com/get-started).
+- **kubectl:**: Command-line tool for interacting with Kubernetes. Install it from [kubernetes.io](https://kubernetes.io/docs/tasks/tools/).
+- **Helm:** Package manager for Kubernetes. Install it from [helm.sh](https://helm.sh/docs/intro/install/).
+- **Docker Desktop/Kind/Minikube:** A local kubernetes cluster. Make sure you have the local cluster running before development.
+- **Make:** Helps in working with the project.
+- **Istio:** Required to test the project with istio. Install from [istio.io](https://istio.io/)
+- **k6:** Required to load test the project. Install from [k6.io](https://k6.io/)
+
+### 2. Clone the Repository
+
+Clone the Elasti repository from GitHub to your local machine:
+
+```
+git clone https://github.com/truefoundry/elasti.git
+cd elasti
+```
+
+> Make sure you checkout the documentation and architecture before making your changes.
+
+### 3. Repository Structure
+
+Understanding the repository structure will help you navigate and contribute effectively to the Elasti project. Below is an overview of the key directories and files in the repository:
+
+```
+.
+├── LICENSE
+├── Makefile
+├── README.md
+├── charts
+├── docs
+├── go.work
+├── go.work.sum
+├── kustomization.yaml
+├── operator
+├── pkg
+├── playground
+├── resolver
+└── test
+```
+
+2 Main Modules:
+
+- **`./operator`:** Contains the code for Kubernetes operator, created using kubebuilder.
+  ```
+  .
+  ├── Dockerfile
+  ├── Makefile
+  ├── api
+  ├── cmd
+  ├── config
+  ├── go.mod
+  ├── go.sum
+  ├── internal
+  └── test
+  ```
+  - **`./api`:** Contains the folder named after the apiVersion, and has custom resource type description.
+  - **`./config`:** Kubernetes manifest files.
+  - **`./cmd`:** Main files for the tool.
+  - **`./internal`:** Internal packages of the program.
+  - **`./Makefile`:** Helps with working with the program. Use `make help` to see all the available commands.
+- **`./resolver`:** Contains the code for resolver.
+  - File structure of it is similar to that of Operator.
+
+Other Directories:
+
+- **`./playground`:** Code to setup a playground to try and test elasti.
+- **`./test`:** Load testing scripts.
+- **`./pkg`:** Common packages, shared via Operator and Resolve.
+- **`./charts`:** Helm chart template.
+- **`./docs`:** Detailed documentation on the HLD, LLD and Architecture of elasti.
+
+## Setup Playground
+
+### 1. Local Cluster
+
+If you don't already have a local Kubernetes cluster, you can set one up using Minikube, Kind or Docker-Desktop:
+
+```
+minikube start
+```
+
+or
+
+```
+kind create cluster
+```
+
+or
+
+Enable it in Docker-Desktop
+
+### 2. Start a Local Docker Registry
+
+Run a local Docker registry container, to push our images locally and access them in our cluster.
+
+```
+docker run -d -p 5000:5000 --name registry registry:2
+```
+
+> You will need to add this registry to Minikube and Kind, with Docker-Desktop, it is automatically picked up if running in same context.
+
+<!-- ### 3. Install NGINX Ingress Controller:
+Install the NGINX Ingress Controller using Helm:
+```
+helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
+helm repo update
+kubectl create namespace nginx
+helm install ingress-nginx ingress-nginx/ingress-nginx -n nginx
+``` -->
+
+### 3. [Optional] Install Istio Gateway to work with istio
+
+```bash
+# Download the latest Istio release from the official Istio website.
+curl -L https://istio.io/downloadIstio | sh -
+# Move it to home directory
+mv istio-x.xx.x ~/.istioctl
+export PATH=$HOME/.istioctl/bin:$PATH
+
+istioctl install --set profile=default -y
+
+# Label the namespace where you want to deploy your application to enable Istio sidecar Injection
+kubectl create namespace demo
+kubectl label namespace demo istio-injection=enabled
+
+# Create a gateway
+kubectl apply -f ./playground/config/gateway.yaml
+```
+
+### 4. Deploy a demo service
+
+Run a demo application in your cluster.
+
+```bash
+kubectl create namespace demo
+kubectl apply -f ./playground/config/demo-application.yaml -n demo
+
+# Create a Virtual Service to expose the demo service if you are using istio
+kubectl apply -f ./playground/config/demo-virtualService.yaml -n demo
+```
+
+### 5. Build & Publish Resolver
+
+Go into the resolver directory and run the build and publish command.
+
+```bash
+cd resolver
+make docker-build docker-push IMG=localhost:5000/elasti-resolver:v1alpha1
+```
+
+### 6. Build & Publish Operator
+
+Go into the operator directory and run the build and publish command.
+
+```bash
+cd operator
+make docker-build docker-push IMG=localhost:5000/elasti-operator:v1alpha1
+```
+
+### 7. Deploy Locally
+
+Make sure you have configured the local context in kubectl. We will be using [`./playground/infra/elasti-demo-values.yaml`](./playground/infra/elasti-demo-values.yaml) for the helm installation. Configure the image uri according to the requirement. Post that follow below steps from the project home directory:
+
+```bash
+helm template elasti ./charts/elasti -n elasti -f ./playground/infra/elasti-demo-values.yaml | kubectl apply -f -
+```
+
+If you want to enable monitoring, please make `enableMonitoring` true in the values file.
+
+### 8. Create ElastiService Resource
+
+Using the [ElastiService Defination](#1-define-a-elastiservice), create a manifest file for your service and apply it. For demo, we use the below manifest.
+
+```bash
+kubectl -n demo apply -f ./playground/config/demo-elastiService.yaml
+```
+
+### 9. Test the service
+
+#### 9.1 Create a watch on the service
+
+```bash
+kubectl -n demo get elastiservice httpbin -w
+```
+
+#### 9.2 Scale down the service
+
+```bash
+kubectl -n demo scale deployment httpbin --replicas=0
+```
+
+#### 9.3 Create a load on the service
+
+```bash
+kubectl run -it --rm curl --image=alpine/curl -- http://httpbin.demo.svc.cluster.local/headers
+```
+
+You should see the target service pod getting scaled up and response from the new pod.
+
+## Testing
+
+This section outlines how to run integration tests, and performance tests using k6.
+
+1. **Update k6 tests**
+
+   Update the `./test/load.js` file, to add your url for testing, and update other configurations in the same file.
+
+2. **Run load.js**
+
+   Run the following command to run the test.
+
+   ```
+   chmod +x ./test/generate_load.sh
+   cd ./test
+   ./generate_load.sh
+   ```
+
+## Monitoring
+
+```bash
+# First, add the prometheus-community Helm repository.
+helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
+helm repo update
+
+
+# Install the kube-prometheus-stack chart. This chart includes Prometheus and Grafana.
+kubectl create namespace prometheus
+helm install prometheus-stack prometheus-community/kube-prometheus-stack -n prometheus
+
+# Port-forward to access the dashboard
+kubectl port-forward -n prometheus services/prometheus-stack-grafana 3000:80
+
+# Get the admin user.
+kubectl get secret --namespace prometheus prometheus-stack-grafana -o jsonpath="{.data.admin-user}" | base64 --decode ; echo
+# Get the admin password.
+kubectl get secret --namespace prometheus prometheus-stack-grafana -o jsonpath="{.data.admin-password}" | base64 --decode ; echo
+```
+
+Post this, you can use [`./playground/infra/elasti-dashboard.yaml`](./playground//infra/elasti-dashboard.yaml) to import the elasti dashboard.