Mastering Microservices with Python, Flask, and Docker

Interested in microservices, and how they can be used for increased agility and scalability?

Microservices is an architectural style and pattern that structures an application as a collection of coherent services. Each service is highly maintainable, testable, loosely coupled, independently deployable, and precisely focused.

This course takes a hands-on look at microservices using Python, Flask, and Docker. You'll learn how Flask can be used to quickly prototype and build microservices, as well as how to use Docker to host and deploy them.

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Project Structure

The Python Flask based microservices project is composed of the following 4 projects:

• frontend
• user-service
• product-service
• order-service

Microservices Setup and Configuration

To launch the end-to-end microservices application perform the following:

Step 1.

Navigate into the frontend directory, and confirm the presence of the docker-compose.deploy.yml file:

cd frontend
ls -la

Step 1.

Create a new Docker network and name it micro_network:

docker network create micro_network

Step 2.

Build each of the microservice Docker container images:

docker-compose -f docker-compose.deploy.yml build
docker images

Step 3.

Launch the microservice environment:

docker-compose up

Step 4.

Prepare each microservice mysql database:

for service in corder-service cproduct-service cuser-service;
do 
 docker exec -it $service flask db init
 docker exec -it $service flask db migrate
 docker exec -it $service flask db upgrade
done

Step 5.

Populate the product database:

curl -i -d "name=prod1&slug=prod1&image=product1.jpg&price=100" -X POST localhost:5002/api/product/create
curl -i -d "name=prod2&slug=prod2&image=product2.jpg&price=200" -X POST localhost:5002/api/product/create

Step 6.

Using your workstations browser - navigate to the following URL and register:

http://localhost:5000/register

Step 7.

Back within your terminal, use a mysql client to confirm that a new user registration record was created:

mysql --host=127.0.0.1 --port=32000 --user=cloudacademy --password=pfm_2020
mysql> show databases;
mysql> use user;
mysql> show tables;
mysql> select * from user;
mysql> exit

Step 8.

Using your workstations browser - login, and add products into your cart, and then finally click the checkout option

http://localhost:5000/login

Step 9.

Back within your terminal, use a mysql client to confirm that a new order has been created:

mysql --host=127.0.0.1 --port=32002 --user=cloudacademy --password=pfm_2020
mysql> show databases;
mysql> use order;
mysql> show tables;
mysql> select * from order.order;
mysql> select * from order.order_item;
mysql> exit

Microservices Teardown

Perform the following steps to teardown the microservices environment:

Step 1.

Create a new Docker network and name it micro_network:

for container in cuser-service cproduct-service corder-service cproduct_dbase cfrontend-app cuser_dbase corder_dbase;
do
 docker stop $container
 docker rm $container
done

Step 2.

Remove the container volumes

for vol in frontend_orderdb_vol frontend_productdb_vol frontend_userdb_vol;
do
 docker volume rm $vol
done

Step 3.

Remove the container network

docker network rm micro_network

Python extensions reference

The following Python extensions were used:

• Flask-SQLAlchemy: https://flask-sqlalchemy.palletsprojects.com/en/2.x/
• Flask-Login: https://flask-login.readthedocs.io/en/latest/
• Flask-Migrate: https://github.com/miguelgrinberg/flask-migrate/
• Requests: https://requests.readthedocs.io/en/master/