AWS Cloud9 Building Docker Image Fail

Question

I'm quite new to networking and server management so thank you in advance for your patience.

Currently I am learning how to build a docker image on AWS's Cloud9.

The tutorial I'm following is from AWS themselves and is named MythicalMysfits which is meant to walk a new user through the main tools used on AWS to build a modern web application.

I'm currently on step 2, building a dynamic website:

https://aws.amazon.com/getting-started/hands-on/build-modern-app-fargate-lambda-dynamodb-python/module-two/

When I run the following command:

docker build . -t REPLACE_ME_AWS_ACCOUNT_ID.dkr.ecr.REPLACE_ME_REGION.amazonaws.com/mythicalmysfits/service:latest 

I of course replace the two parts necessary with my account ID and region.

It prompts another file Named "Dockerfile" containing the following commands to be run:

FROM ubuntu:latest RUN echo Updating existing packages, installing and upgrading python and pip. RUN apt-get update -y RUN apt-get install -y python-pip python-dev build-essential RUN pip install --upgrade pip RUN echo Copying the Mythical Mysfits Flask service into a service directory. COPY ./service /MythicalMysfitsService WORKDIR /MythicalMysfitsService RUN echo Installing Python packages listed in requirements.txt RUN pip install -r ./requirements.txt RUN echo Starting python and starting the Flask service... ENTRYPOINT ["python"] CMD ["mythicalMysfitsService.py"] 

At this point the code begins to run, however fails:

Sending build context to Docker daemon 14.85kB Step 1/13 : FROM ubuntu:latest ---> 1d622ef86b13 Step 2/13 : RUN echo Updating existing packages, installing and upgrading python and pip. ---> Using cache ---> d5aa972842ca Step 3/13 : RUN apt-get update -y ---> Using cache ---> 56374a45d258 Step 4/13 : RUN apt-get install -y python-pip python-dev build-essential ---> Running in 3ce71d802d94 Reading package lists... Building dependency tree... Reading state information... E: Unable to locate package python-pip The command '/bin/sh -c apt-get install -y python-pip python-dev build-essential' returned a non-zero code: 100 

I understand that external to this document, apt-get does not work in Cloud9's IDE so I managed to install the python packages manually using sudo yum. I've spend a few hours over two days now trying to figure it out. I'm also in the correct directory as the tutorial advises.

Do you have any idea as to why the "Dockerfile" is misbehaving?

I thank you again for your time.

Answer 1

I'm also following same tutorial. I had same issue than you.

I solved it by :

• Using python3-pip instead of python-pi
• Using pip3 instead of pip

In Docker file you just need to change following lines:

• Replace line 4 by:

  RUN apt-get install -y python3-pip python-dev build-essential

• Replace line 5 by:

  RUN pip3 install --upgrade pip

• Replace line 10 by:

  RUN pip3 install -r ./requirements.txt

• Replace line 12 by:

  ENTRYPOINT ["python3"]

Answer 2

I changed the first line of the Dockerfile from

FROM ubuntu:latest 

to

FROM ubuntu:18.04 

I cannot say whether this has any cost implications, though.

Answer 3

As a general rule in writing dockerfiles: Can you execute the contents of each RUN line in sequence manually using the command line? This may give you valuable debugging information about where the failure lies.

It appears that apt-get is indeed working and python-pip should be available in Debian/Ubuntu repos.

Docker will sometimes behave in unexpected ways with the build cache especially after modifying a dockerfile and yours is failing after cached operations. The safest way to eliminate this possibility is to remove the cache by running:

docker images docker rmi <image> 

and remove the recent build attempt image to eliminate the cache