Tradebot

Tradebot is a tiny web api made with Go that takes array of stock prices and returns the best profit one could have made from 1 purchase and 1 sale using best practices of running microservices in Kubernetes.

Features

Separation of concerns with middlewares, transport layers and handlers
Multiple transport support ( json/http + ws/http + grpc)
Health checks (readiness and liveness)
Graceful shutdown on interrupt signals
File watcher for secrets and configmaps
Instrumented with Prometheus
Tracing with Istio and Jaeger
Linkerd service profile
Structured logging with zap
12-factor app with viper
Fault injection (random errors and latency) for chaos engineering
Helm and Kustomize installers
End-to-End testing with Kubernetes Kind and Helm
Kustomize testing with GitHub Actions and Open Policy Agent
Expose Kubernetes services over HTTPS with Ngrok
Managing Helm releases the GitOps way
Swagger docs
Web Socket implementation (Since this is a trading API, I thought web socket implementation should be made available. So added a sample implmentation)

API Documentation

Web API:

GET /trade/profit calculates max profit for given prices
GET /version prints tradebot version and git commit hash
GET /metrics return HTTP requests duration and Go runtime metrics
GET /healthz used by Kubernetes liveness probe
GET /readyz used by Kubernetes readiness probe
POST /readyz/enable signals the Kubernetes LB that this instance is ready to receive traffic
POST /readyz/disable signals the Kubernetes LB to stop sending requests to this instance
GET /configs returns a JSON with configmaps and/or secrets mounted in the config volume
GET /ws/echo echos content via websockets cli ws ws://localhost:9898/ws/echo
GET /swagger.json returns the API Swagger docs, used for Linkerd service profiling and Gloo routes discovery

gRPC API:

/grpc.health.v1.Health/Check health checking

Test

Docker:

docker run -dp 9898:9898 praveensastry/tradebot

curl -X POST \
  http://localhost:9898/trade/profit \
  -H 'Cache-Control: no-cache' \
  -H 'Postman-Token: 01d1b1da-64cf-406f-b7f7-ce08859382f1' \
  -d '{
"prices": [10, 7, 5, 8, 11, 9]
}'

Local:

# Clone the source
# In the project root directory run the below command
go run cmd/tradebot/main.go

curl -X POST \
  http://localhost:9898/trade/profit \
  -H 'Cache-Control: no-cache' \
  -H 'Postman-Token: 01d1b1da-64cf-406f-b7f7-ce08859382f1' \
  -d '{
"prices": [10, 7, 5, 8, 11, 9]
}'

P.S. While testing you might have approve access if you see the below dialog

Install on Kubernetes

Helm:

helm repo add tradebot https://praveensastry.github.io/tradebot

helm upgrade --install --wait frontend \
--namespace test \
--set replicaCount=2 \
--set backend=http://backend-tradebot:9898/echo \
tradebot/tradebot

helm test frontend --cleanup

helm upgrade --install --wait backend \
--namespace test \
--set hpa.enabled=true \
tradebot/tradebot

Kustomize:

kubectl apply -k github.com/praveensastry/tradebot//kustomize

Extensions / Improvements

As of now, the API only calculates profit for 1 transcation (1 buy and 1 sell). Ideally the API should accept the no of transactions as request parameter and calculate profit accordingly.
Improve API folder structure by moving handlers, middlewares and transport layers to separate packages / folders
Use a framework like go-kit to get most API features OOB