This shows how to create an environment and sourcing it in dockerfile

Dockerfile

RUN /bin/bash -c "apt-get install tmux -y"
RUN /bin/bash -c "apt-get install htop -y"

# Trying conda environment
RUN  /opt/conda/bin/conda create -y --name myenv python=3.6.8 && \
     /opt/conda/bin/conda clean -ya

RUN echo "source activate myenv" > ~/.bashrc
ENV PATH /opt/conda/envs/myenv/bin:$PATH

# COPY ./app /app
RUN pip install -r /app/requirements.txt

# or

RUN pip install h5py==2.8.0 nltk==3.4 numpy==1.15.4 Pillow==5.3.0 pyyaml tensorboardX==1.2 \
     tensorflow==1.12.0 allennlp==0.8.2 tqdm==4.28.1 torch==1.0.0 
RUN pip install pytorch-transformers

# or

RUN pip install pytorch_pretrained_bert

RUN /opt/conda/envs/myenv/bin/python -c "import nltk; nltk.download('punkt')"

# This is how we can delete the images
# docker images
# docker rmi -f <id>
# docker system prune