App Engine Flexible Environment - Dockerfile Package installs skipped on image build

Question

When building a custom runtime in App Engine flexible environment the lines of my Dockerfile in which I am attempting to install packages seem to be being skipped over. Specifically these two:

RUN add-apt-repository ppa:ubuntugis/ppa

RUN sudo apt-get install -y gdal-bin

The terminal shows that the gcloud app deploy command starts by pulling the python runtime and then skips processing the Dockerfile until this line:

RUN virtualenv /env -p python3.7

This is my whole Dockerfile. When the App tries to start it fails as it cannot find the GDAL package installation that I try to install.

FROM ubuntu:bionic


RUN add-apt-repository ppa:ubuntugis/ppa

RUN sudo apt-get install -y gdal-bin


# Create a virtualenv for dependencies. This isolates these packages from
# system-level packages.
# Use -p python3 or -p python3.7 to select python version. Default is version 2.
RUN virtualenv /env -p python3.7



# Setting these environment variables are the same as running
# source /env/bin/activate.
ENV VIRTUAL_ENV /env
ENV PATH /env/bin:$PATH

# Copy the application's requirements.txt and run pip to install all
# dependencies into the virtualenv.
RUN pip install -r requirements.txt

# Add the application source code.
ADD . /


# Run a WSGI server to serve the application. gunicorn must be declared as
# a dependency in requirements.txt.
CMD gunicorn -b :$PORT main:app

Answer 1

As per your Dockerfile, Cloud Build shouldn't be pulling the Python runtime but the ubuntu:bionic image. Cloud Build will pull the Python runtime when you deploy a non-custom flex app.

I believe you need to set the proper runtime in your app.yaml file, like so:

runtime: custom
env: flex
...

instead of runtime:python.

Also, after trying to use your Dockerfile for a test, I noticed a couple of issues:

• it seems add-apt-repository isn't available by default on the ubuntu:bionic image, I had to install it manually.
• You cannot run sudo in Dockerfile

So your Dockerfile would look something like this:

FROM ubuntu:bionic

RUN apt-get update && apt-get install software-properties-common -y
RUN add-apt-repository ppa:ubuntugis/ppa

RUN apt-get install -y gdal-bin
...