Use reticulate with pyenv

Dockerfile

# https://github.com/rocker-org/rocker/tree/master/r-ubuntu
FROM rocker/r-ubuntu:18.04

RUN apt update && \
        apt install -y \
        make build-essential libssl-dev zlib1g-dev libbz2-dev \
        libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
        xz-utils tk-dev libffi-dev liblzma-dev python-openssl git

RUN curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer | bash && \
        echo 'export PATH="/root/.pyenv/bin:$PATH"' >> ~/.bash_profile && \
        echo 'eval "$(pyenv init -)"' >> ~/.bash_profile && \
        echo 'eval "$(pyenv virtualenv-init -)"' >> ~/.bash_profile

ENV CONFIGURE_OPTS="--enable-shared"

RUN . ~/.bash_profile && \
        pyenv install 3.7.0

RUN Rscript -e 'install.packages("reticulate")'

test

$ docker build -t reticulate-pyenv-test .
$ docker run --rm -it reticulate-pyenv-test R -q
> library(reticulate)
> use_python("/root/.pyenv/versions/3.7.0/bin/python")
> py_discover_config()
python:         /root/.pyenv/versions/3.7.0/bin/python
libpython:      /root/.pyenv/versions/3.7.0/lib/libpython3.7m.so
pythonhome:     /root/.pyenv/versions/3.7.0:/root/.pyenv/versions/3.7.0
version:        3.7.0 (default, Nov 10 2019, 03:29:18)  [GCC 7.4.0]
numpy:           [NOT FOUND]

python versions found: 
 /root/.pyenv/versions/3.7.0/bin/python
 /usr/bin/python
 /usr/bin/python3
> os <- import("os")
> os$system("ls")
bin  boot  dev	etc  home  lib	lib64  media  mnt  opt	proc  root  run  sbin  srv  sys  tmp  usr  var
[1] 0