In this repository, we will create a docker image that includes a simple python flask web application that has the following apis/endpoints:
/creation- provides the time the image was built./dynamic- a dynamic parameters / value provided when the image is built./dockerfile- provides the dockerfile the image was created with (in the image)./- returns an index.html./put- gets a file and stores it on the image runtime./get?filename- returns a file from the lcoal store (that was uploaded previously)./list- list all files that were uploaded previously.
| Requirements |
|---|
| python v3.7.9-alpine |
| Flask |
| Docker |
Flask is a web framework, it’s a Python module that lets you develop web applications easily.
Tutorial How To Build and Deploy a Flask Application Using Docker
Run the following command to create the docker image from src directory
Pass in the -t parameter to name your image flask-app.
Also, Pass in the --build-arg parameter to set the image creation time and the dynamic variable
docker image build --build-arg CREATION_DATE="$(date)" --build-arg DYNAMIC_NUMBER="16" -t flask-app .
Verify that your image shows in your image list:
docker image ls
The -p flag maps a port running inside the container to your host.
In this case, we're mapping the Python app running on port 8080 inside the container to port 8080 on your host.
-d flag means that a Docker container runs in the background of your terminal.
docker run -d -p 8080:8080 --name flask-api-app flask-app
docker pull assiak/flask-app
docker run -d -p 8080:8080 --name flask-api-app assiak/flask-app
Link to DockerHub: https://hub.docker.com/u/assiak
Navigate to http://127.0.0.1:8080 in a browser to see the web application.
If you want to see logs from your application, you can use the docker container logs command.
By default, docker container logs prints out what is sent to standard out by your application.
$ docker container ls
You should see your container id by running this command.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
41b0f0701dfa assiak/flask-app "python app.py" 21 minutes ago Up 21 minutes 0.0.0.0:8080->8080/tcp, :::8080->8080/tcp flask-api-app
$ docker container logs flask-api-app
output should be look like : * ...
* Running on all addresses (0.0.0.0)
* Running on http://127.0.0.1:8080
* Running on http://172.17.0.2:8080
Press CTRL+C to quit
* Restarting with stat
* Debugger is active!
* Debugger PIN: 205-345-037
172.17.0.1 - - [10/Oct/2022 14:56:02] "GET /dockerfile HTTP/1.1" 200 -
172.17.0.1 - - [10/Oct/2022 14:56:05] "GET /list HTTP/1.1" 200 -
172.17.0.1 - - [10/Oct/2022 14:56:06] "GET /get HTTP/1.1" 200 -
172.17.0.1 - - [10/Oct/2022 14:56:08] "GET /put HTTP/1.1" 200 -
docker container stop flask-api-app
$ docker container rm flask-api-app
$ docker image rm flask-app
or
$ docker image rm assiak/flask-app
Use the following command removes any stopped containers, unused volumes and networks, and dangling images.
docker system prune
Dockerfile consists of a set of instructions to create docker image of the application.
1. FROM python:3.7.9-alpine
2. ARG CREATION_DATE
3. ENV DATE=$CREATION_DATE
4. ARG DYNAMIC_NUMBER
5. ENV NUMBER=$DYNAMIC_NUMBER
6. RUN pip install --upgrade pip
7. WORKDIR /flask-app
8. ADD . /flask-app
9. RUN pip install -r requirements.txt
10.CMD ["python","app.py"]
Line by line description:
1. FROM python:3.7.9-alpine
FROM allows us to initialize the build over a base image. In our case, we are using a python:3.7.9-alpine image. (Alpine is a small Linux Distribution (~ 5MB).) In short, we are using a Linux environment with python 3.7.9 for our app.
2. ARG CREATION_DATE
Defines the image creation date variable. we'll set it during build using the --build-arg flag.
3. ENV DATE=$CREATION_DATE
Image creation date environment variable which is passed to the container.
4. ARG DYNAMIC_NUMBER
Defines a dynamic variable provided when image was built. we'll set it during build using the --build-arg flag.
5. ENV NUMBER=$DYNAMIC_NUMBER
Passing the dynamic variable to the container.
6. RUN pip install --upgrade pip
Run instruction to update pip to minimize dependency errors.
7. WORKDIR /flask-app
A work directory called flask-app where the "present working directory" will be set.
8. ADD . /flask-app
Copy everything in the current directory (our server code and configurations) into the flask-app directory.
9. RUN pip install -r requirements.txt
Run pip to install the dependencies of our application.
10. CMD ["python","app.py"]
CMD is the command that is executed when we start a container.
Here, we are using CMD to run a Python applcation.
Get Started with Docker
Build time arguments
Flask Quickstart