Installing rpy2 with Docker is unable to find R path - r

Question

A Django application using Docker needs to install rpy2 as a dependency. Although I install r-base container and specify it as a dependency, when installing django requirements I keep getting:
Collecting rpy2==2.8.3 (from -r /requirements/base.txt (line 55))
Downloading rpy2-2.8.3.tar.gz (186kB)
Complete output from command python setup.py egg_info:
Error: Tried to guess R's HOME but no command 'R' in the PATH.
How can specify inside Docker where the R path is?
My server.yml looks like this:
version: '2'
services:
r:
build: ./services/r
django:
build:
context: ./myproject/
dockerfile: ./compose/django/Dockerfile
env_file:
- .env
- .env-server
environment:
- DATABASE_URL=postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}#postgres:5432/${POSTGRES_USER}
depends_on:
- postgres
- r
command: /gunicorn.sh
volumes:
- ./myproject:/app
The Dockerfile for django is:
FROM python:2.7
ENV PYTHONUNBUFFERED 1
COPY ./requirements /requirements
RUN pip install -r /requirements/production.txt \
&& pip install -r /requirements/test.txt \
&& groupadd -r django \
&& useradd -r -g django django
COPY . /app
RUN chown -R django /app
COPY ./compose/django/gunicorn.sh /gunicorn.sh
COPY ./compose/django/entrypoint.sh /entrypoint.sh
RUN sed -i 's/\r//' /entrypoint.sh \
&& sed -i 's/\r//' /gunicorn.sh \
&& chmod +x /entrypoint.sh \
&& chown django /entrypoint.sh \
&& chmod +x /gunicorn.sh \
&& chown django /gunicorn.sh
WORKDIR /app
ENTRYPOINT ["/entrypoint.sh"]
The Dockerfile for R is:
FROM r-base

Answer 1

It was easier to just install r inside the django container. So removing the r container and modifiying the django docker file adding this lines, worked:
RUN apt-get --force-yes update \
&& apt-get --assume-yes install r-base-core