Running Your Dockerized Voting App (Without Docker Compose)

Prerequisites

Before we begin, ensure you have the following installed on your machine:

• Docker Desktop: This includes the Docker Engine and Docker CLI. You can download it from Docker's official website.

• Git: To clone the project repository.

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Step 1: Clone the GitHub Repository

First, you need to get the application code and Dockerfiles onto your local machine. Replace <https://github.com/dockersamples/example-voting-app.git> with the actual URL of your GitHub repository.

git clone https://github.com/dockersamples/example-voting-app.git
cd example-voting-app # Navigate into the cloned project directory

Now, your current terminal directory should be the root of your cloned repository, where you'll find the vote/, worker/, result/ directories, and potentially a docker-compose.yml (though we won't be using that file for these instructions).

Step 2: Build Docker Images for Each Service

Navigate into each service's directory from your repository root and build its Docker image.

1. Build vote app image:

    cd vote
    docker build -t voting-app .
    cd ..
   

2. Build worker app image:

    cd worker
    docker build -t worker-app .
    cd ..
   

3. Build result app image:

    cd result
    docker build -t result-app .
    cd ..
   

Step 3: Run Docker Containers (Order Matters!)

Now, we'll run each container. It's crucial to start the database and Redis first, as the worker and result apps depend on them.

1. Run redis container:

   This uses the official redis image

    docker run -d --name=redis redis
   

2. Run db (PostgreSQL) container:

   This uses the official postgres image, sets up the database name and credentials.

    docker run -d --name=db -e POSTGRES_USER=postgres -e POSTGRES_PASSWORD=postgres postgres
   

   (Note: Docker will automatically create the db-data volume if it doesn't exist.)

3. Run worker container:

   This uses the worker-app image we built and passes the necessary environment variables for connecting to Redis and PostgreSQL.

    docker run -d --link redis:redis --link db:db worker-app
   

4. Run vote container:

   This uses the vote-app image and maps host port 5000 to container port 80 for web access.

    docker run -d --link redis:redis -p 5000:80 voting-app
   

5. Run result container:

   This uses the result-app image, maps host port 5001 to container port 80, and passes environment variables for PostgreSQL connection.

    docker run -d -p 5001:80 --link db:db result-app
   

Step 4: Verify and Access Your Application

After running all the commands, you can check if all containers are running:

docker ps

You should see redis, db, worker, vote, and result listed with Up status.

Now, open your web browser to access the applications:

• Voting App: http://localhost:5000

• Result App: http://localhost:5001

Step 5: Clean Up (Stop and Remove Containers/Network)

When you're done, it's good practice to stop and remove the containers and the custom network to free up resources.

1. Stop all containers:

    docker stop vote result worker db redis
   

2. Remove all containers:

    docker rm vote result worker db redis
   

This detailed sequence of docker commands will get your multi-service voting application up and running without relying on Docker Compose.