Unable to run Docker image that was built from scratch

Docker
#1

Hello Team,

I have followed the instructions to create a docker image file as mentioned in the lecture:

  1. Created a docker file
  2. Added instructions in the docker file
  3. Created an image of the application(in this case my-simple-webapp)
  4. I could see the image upon executing the command ‘docker run images’

However, while trying to run the newly created image my-simple-webapp, I am facing an issue as shown below

image
image828×500 71.4 KB

Could you please help if I am missing something?

Regards
Sudheer

#2

Hi @sudhir560

Please post the Dockerfile.

Put it inside a code block like this

Not a screenshot.

Thanks

#3

Hello @Alistair_KodeKloud

Here is the docker file i used:
FROM ubuntu

RUN apt-get update
RUN apt-get install -y python3 python3-pip
RUN pip install flask

COPY app.py opt/app.py

ENTRYPOINT FLASK_APP = app.py flask run --host = 0.0.0.0

Let me know if anything else is required.

Regards
Sudheer

#4

Try this

FROM ubuntu

RUN apt-get update
RUN apt-get install -y python3 python3-pip
RUN pip install flask

COPY app.py /opt/app.py
ENV FLASK_APP=app
WORKDIR /opt
ENTRYPOINT ["flask", "run", "--host=0.0.0.0" ]

You can also debug inside the container if it doesn’t successfully start by running the image to a command prompt and running flask from the command line until you get the right arguments - then rebuild the image again…

docker run -it --rm --entrypoint /bin/sh my-simple-webapp
#5

Things to note with this.

  • Set the FLASK_APP environment variable with the ENV command
  • FLASK_APP defaults to .py, hence only need to specify app
  • ENTRYPOINT is a JSON array of the command and its arguments
  • WORKDIR sets the default directory in the container.
#6

Thank you @Alistair_KodeKloud. This helped.
I am now able to run the application from the image.

Regards
Sudheer