support custom ennvironment packages by environemnt.yml (Azure#1005)

Author: banibrata-de

Diff for: .devcontainer/Dockerfile

@@ -25,3 +25,8 @@ WORKDIR /root/.jupyter
 COPY jupyter_server_config.py jupyter_server_config.py
 WORKDIR /root
 COPY  .start.sh .start_jupyter.sh
+
+# This is to support updating conda environment with user supplied packages with environment.yml
+COPY environment.yml* no_op.txt /tmp/conda-tmp/
+RUN if [ -f "/tmp/conda-tmp/environment.yml" ]; then umask 0002 && /miniconda/bin/conda env update -n base -f /tmp/conda-tmp/environment.yml; fi \
+    && rm -rf /tmp/conda-tmp

Diff for: .devcontainer/no_op.txt

@@ -0,0 +1,3 @@
+This file is copied into the container along with environment.yml* from the
+parent folder. This is done to prevent the Dockerfile COPY instruction from 
+failing if no environment.yml is found.