yanivbh1/FastMart

A groceries delivery app

For the full version of the tutorial, please head here.

Meet Fastmart — The fastest and most reliable food delivery app ever built.

The stack we will use -

• MongoDB for orders persistency.
• Node.js as our primary dev-lang.
• Memphis.dev as the used message broker.
• Kubernetes to host our microservices.

Event-driven architecture using Message Broker

High-Level Plan

1. Sign up to Memphis Cloud here.
2. Clone “Fastmart” GitHub repo.
3. Review the code, the different services, and how they interact with each other
4. Deploy “Fastmart” over Kubernetes
5. Order food!

Let’s start!

1. Sign up to Memphis.dev Cloud

Please head to Memphis.dev Cloud Signup, and create a free acount.

Memphis.dev Dashboard

2. Clone the Fastmart repo

git clone https://github.com/yanivbh1/FastMart.git

3. Review the System Architecture, Code, and Flow

Follow the numbers to understand the flow.

FastMart has three main components:

**order-service** - Exposes REST endpoints that allow clients to fetch the food menu, place an order and track the order in real-time.

A new order will be saved in mongo with the status “Pending” and will be produced (Pushed) into the “orders” station

GET: /<orderId>  
Example: curl [http://order-service:3000/30](http://order-service:3000/30)POST: /<order\_details>  
Example: curl -X POST [http://order-service:3000/api/orders](http://order-service:3000/api/orders) -d ‘{“items”:\[{“name”:”burger”,”quantity”:1}\], “email”:”test@test.com”}’ -H ‘Content-Type: application/json’

The code responsible for communicating with Memphis will be found on -

./order-service/src/services/mqService.js

**email-service** - Responsible for notifying the client of the different stages.

email-service consumer messages from two stations: orders and notifications.

As soon as an order is inserted into the station, the email service notifies the client with an order confirmation.

At the same time listens for new notification requests of other services

**resturant-service** - Responsible for fulfilling an order.

1. Consume an order
2. Process the order
3. Change order status at the MongoDB level to “Accepted”
4. Using constant sleep time to mimic the preparation of the food by the restaurant
5. Change order status at the MongoDB level to “Delivered”
6. Sending notifications to the client

4. Deploy “Fastmart” over Kubernetes

Fastmart repo tree -

Fastmart files tree

To deploy the Fastmart namespace and different services,

please run kubectl apply -f k8s-deployment.yaml

kubectl get pods -n fastmart

Output -

Let’s understand why Fastmart services cant start

kubectl logs email-service-5ddb9b58d6-bq2xd -n fastmart

Output -

It appears that the services try to connect to “Memphis” with the user “Fastmart” which does not exist, and we require to create it.

Once the user gets created, the pods will restart automatically and reconnect with Memphis.

5. Order food!

To expose the orders-service through localhost, run -

kubectl port-forward service/orders 9001:80 --namespace fastmart > /dev/null &

Get the menu

curl localhost:9001/api/menu

Output -

{“items”:\[{“name”:”burger”,”price”:50},{“name”:”fries”,”price”:20},{“name”:”coke”,”price”:10}\]}

Make an order

curl -X POST localhost:9001/api/orders -d ‘{“items”:\[{“name”:”burger”,”quantity”:1}\], “email”:”test@gmail.com”}’ -H ‘Content-Type: application/json’

An email should arrive shortly at the email address specified above.

Thanks!

Join 4500+ others and sign up for our data engineering newsletter.