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Development Tools Introduction to Docker Building Images Using Dockerfiles The ENTRYPOINT and CMD Instructions

Juliette Tworsey
.a{fill-rule:evenodd;}techdegree seal-36
Juliette Tworsey
Front End Web Development Techdegree Graduate 32,425 Points

Docker course files?


Are the course files available for download somewhere?

Also, I am unable to connect to localhost:8080. What could be the issue?

Here is my Dockerfile:

# Base image
FROM ubuntu:latest

# Commands to run to install dependencies
RUN apt-get update -y
RUN apt-get install -y python3

# When you pass commands to the container, what should interpret them
ENTRYPOINT ["python3"]

# Command to run when the container starts
CMD ["app.py"]

# Working directory

# Copy apps from the local folder to the Docker container
COPY app.py app.py
COPY alternate.py alternate.py

# Make port available


3 Answers

Jared Smith
Jared Smith
Treehouse Guest Teacher

Hi Juliette,

Make sure when you run the Docker container, that you pass the -p option with 8080:8080 as the argument, or else Docker will not bind the exposed container port to your computer's interface.

See the docs here: https://docs.docker.com/engine/reference/run/#expose-incoming-ports

Best, Jared

Juliette Tworsey
.a{fill-rule:evenodd;}techdegree seal-36
Juliette Tworsey
Front End Web Development Techdegree Graduate 32,425 Points

Hi Jared,

Thanks for getting back to me!

These are the commands that I am running from my home directory:

docker build -t sample-web-app:1.0 .

docker run -p 8080:8080 sample-web-app

Localhost is (still) refusing to connect and I'm not sure what to do to get it to start.

I had no problem starting a mongod instance (and mongo) from within Docker, but this one is eluding me.

Thanks in advance for any further clues:-)

Yash Gopal
Yash Gopal
4,638 Points

Make sure no other containers are using the same ports? Maybe try stopping all containers and re-running those commands from within the directory that you have the dockerfile / project in.

localhost doesn't work if you are using docker-toolbox on Windows because it has to use Virtualbox. You'll need to use the IP address of the virtual machine docker creates, which is So you would connect using