condas `source activate virtualenv` does not work

Question

Scenario

I'm trying to setup a simple docker image (I'm quite new to docker, so please correct my possible misconceptions) based on the public continuumio/anaconda3 container.

The Dockerfile:

FROM continuumio/anaconda3:latest

# update conda and setup environment
RUN conda update conda -y \
    && conda env list \
    && conda create -n testenv pip -y \
    && source activate testenv \
    && conda env list

Building and image from this by docker build -t test . ends with the error:

/bin/sh: 1: source: not found

when activating the new virtual environment.

Suggestion 1:

Following this answer I tried:

FROM continuumio/anaconda3:latest

# update conda and setup environment
RUN conda update conda -y \
    && conda env list \
    && conda create -y -n testenv pip \
    && /bin/bash -c "source activate testenv" \
    && conda env list

This seems to work at first, as it outputs: prepending /opt/conda/envs/testenv/bin to PATH, but conda env list as well ass echo $PATH clearly show that it doesn't:

[...]
# conda environments:
#
testenv                  /opt/conda/envs/testenv
root                  *  /opt/conda

---> 80a77e55a11f
Removing intermediate container 33982c006f94
Step 3 : RUN echo $PATH
---> Running in a30bb3706731
/opt/conda/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

The docker files work out of the box as a MWE. I appreciate any ideas. Thanks!

Answer 1

Piggybacking on ccauet's answer (which I couldn't get to work), and Charles Duffey's comment about there being more to it than just PATH, here's what will take care of the issue.

When activating an environment, conda sets the following variables, as well as a few that backup default values that can be referenced when deactivating the environment. These variables have been omitted from the Dockerfile, as the root conda environment need never be used again. For reference, these are CONDA_PATH_BACKUP, CONDA_PS1_BACKUP, and _CONDA_SET_PROJ_LIB. It also sets PS1 in order to show (testenv) at the left of the terminal prompt line, which was also omitted. The following statements will do what you want.

ENV PATH /opt/conda/envs/testenv/bin:$PATH
ENV CONDA_DEFAULT_ENV testenv
ENV CONDA_PREFIX /opt/conda/envs/testenv

In order to shrink the number of layers created, you can combine these commands into a single ENV command setting all the variables at once as well.

There may be some other variables that need to be set, based on the package. For example,

ENV GDAL_DATA /opt/conda/envs/testenv/share/gdal
ENV CPL_ZIP_ENCODING UTF-8
ENV PROJ_LIB /opt/conda/envs/testenv/share/proj

The easy way to get this information is to call printenv > root_env.txt in the root environment, activate testenv, then call printenv > test_env.txt, and examine diff root_env.txt test_env.txt.

Answer 2

Using the docker ENV instruction it is possible to add the virtual environment path persistently to PATH. Although this does not solve the selected environment listed under conda env list.

See the MWE:

FROM continuumio/anaconda3:latest

# update conda and setup environment
RUN conda update conda -y \
    && conda create -y -n testenv pip

ENV PATH /opt/conda/envs/testenv/bin:$PATH

RUN echo $PATH
RUN conda env list