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Load Balancing Containers

For the last six months, the Acme Anvil Corporation has been migrating some of their bare metal infrastructure to Docker containers. The initial implementation was very basic and lacked any kind of load balancing. Your manager has tasked you with creating two proofs of concept. For the first proof of concept, you are to use Docker Compose to create an Nginx load balancer and three instances using your `weather-app` image. Nginx will use port 80 and send traffic to port 3000 on the `weather-app` containers. For the second proof of concept, you are to create a Docker Swarm service called `nginx-app` that has two replicas using the Nginx image. The service should be published to port 8080 on the host and target port 80 on the containers.

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Path Info

Level

Intermediate

Duration

1h 30m

Last updated

Aug 30, 2025

Challenge

Create a Docker Compose file.

The containers of your docker-compose.yml should look like the following:

version: '3.2'
services:
  weather-app1:
      build: ./weather-app
      tty: true
      networks:
       - frontend
  weather-app2:
      build: ./weather-app
      tty: true
      networks:
       - frontend
  weather-app3:
      build: ./weather-app
      tty: true
      networks:
       - frontend

  loadbalancer:
      build: ./load-balancer
      image: nginx
      tty: true
      ports:
       - '80:80'
      networks:
       - frontend

networks:
  frontend:

Challenge

Update `nginx.conf`.

The contents of your nginx.conf file should look like the following:

events { worker_connections 1024; }

http {
  upstream localhost {
    server weather-app1:3000;
    server weather-app2:3000;
    server weather-app3:3000;
  }
  server {
    listen 80;
    server_name localhost;
    location / {
      proxy_pass http://localhost;
      proxy_set_header Host $host;
    }
  }
}

Challenge

Execute `docker-compose up`.
Execute a docker-compose up:
```
/usr/local/bin/docker-compose up --build -d
```
Challenge

Create a Docker service using Docker Swarm.
Create a Docker service by executing the following command:
```
docker service create --name nginx-app --publish published=8080,target=80 --replicas=2 nginx
```

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