Docker build and run with Miniconda environments on Ubuntu host - docker

Question

I am in the process of creating a docker container which has a miniconda environment setup with some packages (pip and conda). Dockerfile :
# Use an official Miniconda runtime as a parent image
FROM continuumio/miniconda3
# Create the conda environment.
# RUN conda create -n dev_env Python=3.6
RUN conda update conda -y \
&& conda create -y -n dev_env Python=3.6 pip
ENV PATH /opt/conda/envs/dev_env/bin:$PATH
RUN /bin/bash -c "source activate dev_env" \
&& pip install azure-cli \
&& conda install -y nb_conda
The behavior I want is that when the container is launched, it should automatically switch to the "dev_env" conda environment but I haven't been able to get this to work. Logs :
dparkar#mymachine:~/src/dev/setupsdk$ docker build .
Sending build context to Docker daemon 2.56kB
Step 1/4 : FROM continuumio/miniconda3
---> 1284db959d5d
Step 2/4 : RUN conda update conda -y && conda create -y -n dev_env Python=3.6 pip
---> Using cache
---> cb2313f4d8a8
Step 3/4 : ENV PATH /opt/conda/envs/dev_env/bin:$PATH
---> Using cache
---> 320d4fd2b964
Step 4/4 : RUN /bin/bash -c "source activate dev_env" && pip install azure-cli && conda install -y nb_conda
---> Using cache
---> 3c0299dfbe57
Successfully built 3c0299dfbe57
dparkar#mymachine:~/src/dev/setupsdk$ docker run -it 3c0299dfbe57
(base) root#3db861098892:/# source activate dev_env
(dev_env) root#3db861098892:/# exit
exit
dparkar#mymachine:~/src/dev/setupsdk$ docker run -it 3c0299dfbe57 source activate dev_env
[FATAL tini (7)] exec source failed: No such file or directory
dparkar#mymachine:~/src/dev/setupsdk$ docker run -it 3c0299dfbe57 /bin/bash source activate dev_env
/bin/bash: source: No such file or directory
dparkar#mymachine:~/src/dev/setupsdk$ docker run -it 3c0299dfbe57 /bin/bash "source activate dev_env"
/bin/bash: source activate dev_env: No such file or directory
dparkar#mymachine:~/src/dev/setupsdk$ docker run -it 3c0299dfbe57 /bin/bash -c "source activate dev_env"
dparkar#mymachine:~/src/dev/setupsdk$
As you can see above, when I am within the container, I can successfully run "source activate dev_env" and the environment switches over. But I want this to happen automatically when the container is launched.
This also happens in the Dockerfile during build time. Again, I am not sure if that has any effect either.

Answer 1

You should use the command CMD for anything related to runtime.
Anything typed after RUN will only be run at image creation time, not when you actually run the container.
The shell used to run such commands is closed at the end of the image creation process, making the environment activation non-persistent in that case.
As such, your additional line might look like this:
CMD ["conda activate <your-env-name> && <other commands>"]
where <other commands> are other commands you might need at runtime after the environment activation.

Answer 2

This docker build file worked for me.
# start with miniconda image
FROM continuumio/miniconda3
# setting the working directory
WORKDIR /usr/src/app
# Copy the file from your host to your current location in container
COPY . /usr/src/app
# Run the command inside your image filesystem to create an environment and name it in the requirements.yml file, in this case "myenv"
RUN conda env create --file requirements.yml
# Activate the environment named "myenv" with shell command
SHELL ["conda", "run", "-n", "myenv", "/bin/bash", "-c"]
# Make sure the environment is activated by testing if you can import flask or any other package you have in your requirements.yml file
RUN echo "Make sure flask is installed:"
RUN python -c "import flask"
# exposing port 8050 for interaction with local host
EXPOSE 8050
#Run your application in the new "myenv" environment
CMD ["conda", "run", "-n", "myenv", "python", "app.py"]