Edit the `Dockerfile`¶

Introducing

the Dockerfile
using RUN in the Dockerfile

Your Dockerfile will look much like this:

FROM divio/base:4.15-py3.6-slim-stretch

ENV PIP_INDEX_URL=${PIP_INDEX_URL:-https://wheels.aldryn.net/v1/aldryn-extras+pypi/${WHEELS_PLATFORM:-aldryn-baseproject-py3}/+simple/} \
    WHEELSPROXY_URL=${WHEELSPROXY_URL:-https://wheels.aldryn.net/v1/aldryn-extras+pypi/${WHEELS_PLATFORM:-aldryn-baseproject-py3}/}
COPY requirements.* /app/
COPY addons-dev /app/addons-dev/
RUN pip-reqs compile && \
    pip-reqs resolve && \
    pip install \
        --no-index --no-deps \
        --requirement requirements.urls

COPY . /app

RUN DJANGO_MODE=build python manage.py collectstatic --noinput

It contains a series of instructions that are used to build the project’s image. For example, the highlighted line above runs a Django command to collect static files.

Use `RUN` to install a package in the image¶

We want to add the commands we used (apt-get update and apt-get install libwebp-dev to install libwebp-dev. Add two lines as indicated:

FROM divio/base:4.15-py3.6-slim-stretch

RUN apt-get update
RUN apt-get install libwebp-dev -y

ENV PIP_INDEX_URL=${PIP_INDEX_URL:-https://wheels.aldryn.net/v1/aldryn-extras+pypi/${WHEELS_PLATFORM:-aldryn-baseproject-py3}/+simple/} \

By making a change to the Dockerfile, you’ve made a change to the instructions that build it. To use these new instructions, you will need to rebuild the project:

docker-compose build

And now you can try once more to open a Python shell and open a WebP image as you did in the previous section. In fact you can launch a Python shell directly with:

docker-compose run web python

and then run:

>>> from PIL import Image
>>> Image.open("test.webp")

And this time it will work - because you have baked support for WebP into the environment.

Explanation

Further reading: Understanding the Dockerfile

Edit the Dockerfile¶

Use RUN to install a package in the image¶

Edit the `Dockerfile`¶

Use `RUN` to install a package in the image¶