docker-compose up -d

cd {serviceName} && go test ./...

Sometimes when we start the DB and Kafka, we get an error and are stuck in infinite restart like [error] failed to initialize database, got error dial tcp 192.168.176.5:3306: connect: connection refused that’s because the MySQL or Kafka not starting yet. Since we always retry by always: restart inside docker-compose, the container will restart until the MySQL and Kafka completely start.

We are using Open Tracing and Jaeger to trace that can be accesed through: http://localhost:16686/

We utilize event or service choreography to handle the transactions, it will rollback all the changes if any of the service fails. In our case when the stock is exceeded, then the order service will cancel the order.

Product service API can be run by go run . serve command. Documentation and the API are listed in GraphQL: http://127.0.0.1:8080

• Serve the frontend by given queries
• Check current stock by RPC call to Stock services.

Order service API can be run by go run . serve command.

Order service only creates the record to DB and trigger order.created event that Stock services will llisten.

• Creating order.
• Canceling order if the stock is exceeded by checking the stock to stock services.

Request

curl --location --request POST 'http://127.0.0.1:3000/api/v1/orders' \--header 'Content-Type: application/json' \--data-raw '{    "product_id": 1,    "total_price": 10000,    "total_quantity": 1}'

Response

Order created

Order service listener can be run by go run . listen command.

• Cancel order
  • This service will listen to all topics related to order, such as stock.exceeded-amount it will cancel the order if the selected order is matched and mark the order canceled by adding is_canceled to be true.

Stock service listener can be run by go run . serve command.

• Serve RPC server to product services to the current stock of a given product.

Stock service listener can be run by go run . listen command.

Responsibilities

• Listening for all orders created events by Order services to support saga pattern
  • It will decrease a stock when a new order comes up
  • If the order stock is exceeded, then it will publish the stock.exceeded-amount events that Order services will listen.
• Stock service listener is listening for only one topic: order.created and will send all of the failure to order.created.dlq topic.