Download the sample code

git clone https://github.com/lin-chen-Langley/count
        

Fetch Redis image to local docker daemon

# docker login
docker image pull redis
        

Run Redis image as a container

docker run -d -p 6379:6379 redis
        

Run Count in local

# install needed dependencies

# run app
python app.py

# access app
http://localhost:5000/
        

Create an Docker Hub account if you do not have one

https://hub.docker.com/
        

Create a Dockerfile in your code folder

# Dockerfile
FROM python:3.7-alpine # build image from python:3.7
WORKDIR /code # set up default directory
ENV FLASK_APP=app.py
ENV FLASK_RUN_HOST=0.0.0.0
RUN apk add --no-cache gcc musl-dev linux-headers # install needed Linux tools
COPY requirements.txt requirements.txt # copy a file from local to image
RUN pip install -r requirements.txt # install dependencies of the app
EXPOSE 5000
COPY . . # copy all files in the current folder to image
CMD ["python", "app.py"] # run the command when run the image as container
        

Create an image for Count

docker build -t lchenlangley/count .
        

Push the image to a registry

# docker login
docker push lchenlangley/count
        

Create a compose file

# compose.yaml
version: "3.9" # version of Docker Compose
services:
  webapp: # create a container for Count
    image: lchenlangley/count # load image from DockerHub
    ports:
      - 8000:5000 # port mapping
    environment:
      - MYREDIS_HOST=redisserver # pass ip of redisserver to webapp
      - FLASK_ENV=development
  redisserver: # create a container for redis
    image: "redis:alpine" # load image from DockerHub
        

Run the app

# compose containers
docker-compose up

# access app
http://localhost:8000/
        

1. Run the app with docker-compose up

2. Update the app, change Hello World from Docker to Hello [Your Name]

3. Create an image for the updated code, the image name should be [your_dockerhub_username]/count

4. Push the built image to Docker Hub

5. Rerun the app