Amalgam

In this demo, you will see how you can use Zrb to:

• Create a modular-monolith CRUD application.
• Add some entities/fields.
• Run the application as monolith/microservices.
• Containerize your application.
• Deploy the application to a Kubernetes cluster.

No coding skill is required.

Start the demo

Before starting the demo, you need to make sure you have the following software installed:

• Python (3.9 or higher)
• Pip
• Venv
• Docker (with Docker Compose extension)
• Pulumi
• Node.Js
• Npm
• Zrb
• Access to a Kubernetes cluster

Note: Installing docker desktop will give you docker + docker compose extension, as well as local kubernetes cluster (if enabled).

Once everything is set, you can run the following commands on your terminal:

echo "👷 Crete my-project"
zrb project create --project-dir my-project --project-name "My Project"
cd my-project
source project.sh

echo "👷 Add fastapp"
zrb project add fastapp app --project-dir . --app-name "myapp" --http-port 3000

echo "👷 Add library module"
zrb project add fastapp module --project-dir . --app-name "myapp" --module-name "library"

echo "👷 Add book entity"
zrb project add fastapp crud --project-dir . --app-name "myapp" --module-name "library" \
    --entity-name "book" --plural-entity-name "books" --column-name "code"

echo "👷 Add title field"
zrb project add fastapp field --project-dir . --app-name "myapp" --module-name "library" \
    --entity-name "book" --column-name "title" --column-type "string"

echo "👷 Add page_number field"
zrb project add fastapp field --project-dir . --app-name "myapp" --module-name "library" \
    --entity-name "book" --column-name "page_number" --column-type "integer"

echo "👷 Add purchase_date field"
zrb project add fastapp field --project-dir . --app-name "myapp" --module-name "library" \
    --entity-name "book" --column-name "purchase_date" --column-type "date"

echo "👷 Add available field"
zrb project add fastapp field --project-dir . --app-name "myapp" --module-name "library" \
    --entity-name "book" --column-name "available" --column-type "boolean"

echo "👷 Add synopsis field"
zrb project add fastapp field --project-dir . --app-name "myapp" --module-name "library" \
    --entity-name "book" --column-name "synopsis" --column-type "text"

echo "👷 Start fastapp"
zrb project myapp monolith start

The commands will give you:

• A folder named my-project.
• A Python application under the project (my-project/src/myapp).
• A library module under the application (myproject/src/myapp/src/module/library)
• A book entity under the library module.
• A field named title under the book entity.

It will also run the application on your local computer.

Open myapp from the browser

You can visit http://localhost:3000 to see how the application works.

The default username and password will be root and toor.

Try to add some books.

Override default username and password

You can override the system username and password by setting some environment variables:

# press ctrl + c to stop the application
export MYAPP_APP_AUTH_ADMIN_USERNAME=gofrendi
export MYAPP_APP_AUTH_ADMIN_PASSWORD=aVeryStrongPassword73
zrb project myapp monolith start 

Checking the process

Currently, myapp is running as a single process on your local computer.

Let's confirm this by opening a new terminal and invoking the following command:

pgrep uvicorn -a

You should see a single process like this:

4001 ... main:app --host 0.0.0.0 --port 3000 --reload --reload-include index.html

Run Myapp as Microservices

Now let's go back to your first terminal; so that you can kill my-app process by pressing ctrl + c.

Stay in your first terminal, and try to invoke the following command:

zrb project myapp microservices start

Once started, you will be able to access http://localhost:3000 as you have done previously.

Now let's invoke the following command on your second terminal:

pgrep uvicorn -a

5305 ... main:app --host 0.0.0.0 --port 3000 --reload --reload-include index.html
5307 ... main:app --host 0.0.0.0 --port 3001 --reload --reload-include index.html
5309 ... main:app --host 0.0.0.0 --port 3002 --reload --reload-include index.html
5311 ... main:app --host 0.0.0.0 --port 3003 --reload --reload-include index.html

You can see that now you have multiple processes.

Each process handles different aspect of the application:

• myapp-gateway (port: 3000)
  • Handle HTTP requests from user
  • Send RPC requests to other services
  • Consume RPC replies from other services
• myapp-auth-service (port: 3001)
  • Handle RPC requests related to authentication/authorization
  • Send RPC responses to Gateway
• myapp-log-service (port: 3002)
  • Handle RPC requests related to user activities/entities change history
  • Send RPC responses to Gateway
• myapp-library-service (port: 3002)
  • Handle RPC requests related to book management
  • Send RPC response to Gateway

You can see that you can run myapp as either microservices or as a Monolith.

Run Myapp as containers

Now let's run myapp as containers.

Let's go back to your first terminal, and kill the running process by pressing ctrl + c.

To run myapp as containers you can invoke:

zrb project myapp container microservices start

Note: You can also run the container as a monolith if you want to. Just invoke zrb project myapp container monolith start

Now let's see how things look like by invoking:

docker ps

CONTAINER ID   IMAGE                   ...  PORTS                    NAMES
868a7e089983   gofrendi/myapp:latest   ...  0.0.0.0:3003->3003/tcp   myapp_library_service
022bd4d3c86c   rabbitmq:3-management   ...  4369/tcp, 5671/tcp ...   myapp_rabbitmq
afcdbface5b0   adminer                 ...  0.0.0.0:9001->8080/tcp   myapp_adminer
cd5fa960db85   gofrendi/myapp:latest   ...  0.0.0.0:3002->3002/tcp   myapp_log
5ea14febc9a2   gofrendi/myapp:latest   ...  0.0.0.0:3001->3001/tcp   myapp-auth
94d382af67ed   gofrendi/myapp:latest   ...  0.0.0.0:3000->3000/tcp   myapp_gateway
20b30ae224d1   postgres:15.2           ...  0.0.0.0:5432->5432/tcp   myapp_postgresql

You will still able to access http://localhost:3000 as you previously do. The application is now running as containers.

You can stop the container by pressing ctrl + c in your first terminal.

Make sure to also run zrb project stop-myapp-container to prevent your containers to be auto-started.

Deploying Myapp to Kubernetes

For this demo, we are using docker desktop with kubernetes enabled.

Once your kubernetes cluster is running, you can invoke the following command:

docker login
zrb project myapp microservices deploy

Now let's invoke kubectl get pods and see how the pods are running

NAME                                             READY   STATUS    RESTARTS        AGE
myapp-auth-service-f8ae1d6e-85f4c9546b-snxsg     1/1     Running   0               11m
myapp-gateway-1ef04e6a-675c677c99-cnlj4          1/1     Running   0               11m
myapp-library-service-ea122a8e-cd66f54db-hgkvf   1/1     Running   0               11m
myapp-log-service-2985aef5-6fbcdd8fbd-jfg28      1/1     Running   0               11m
postgresql-0                                     1/1     Running   0               14m
rabbitmq-0                                       1/1     Running   0               76s

You can also invoke kubectl get services to see how the network is configured

NAME                     TYPE           CLUSTER-IP       EXTERNAL-IP   PORT(S)                 AGE
kubernetes               ClusterIP      10.96.0.1        <none>        443/TCP                 12h
myapp-gateway-e212b722   LoadBalancer   10.106.184.165   localhost     3000:31723/TCP          14m
postgresql               ClusterIP      10.108.147.124   <none>        5432/TCP                17m
postgresql-hl            ClusterIP      None             <none>        5432/TCP                17m
rabbitmq                 ClusterIP      10.104.181.249   <none>        5672/TCP,4369/TCP,...   17m
rabbitmq-headless        ClusterIP      None             <none>        4369/TCP,5672/TCP,...   17m

And as always you you can access http://localhost:3000.

Conclusion

With Zrb, you can develop and deploy your application easily.

Further reading

• Zrb documentation
• MyApp documentation
  • Modular monolith concept