try to cut down size of Docker container

.dockerignore

@@ -0,0 +1,2 @@
+.git
+.dockerignore

Dockerfile

@@ -1,22 +1,27 @@
 FROM continuumio/miniconda3:4.9.2-alpine
-LABEL authors="" \
-      version="2.1.2" \
+LABEL version="2.1.2" \
       description="Docker image for Pangolin"
 
 # Install git for pangolin
 RUN apk update && \
     apk add git bash
 
+COPY environment.yml /environment.yml
+# Python 3.8.5 already installed along with recent version of pip
+# so remove Python and pip deps from environment.yml before installation
+RUN sed -i "$(grep -n python=3.7 /environment.yml | cut -f1 -d:)d" /environment.yml && \
+    sed -i "$(grep -n pip= /environment.yml | cut -f1 -d:)d" /environment.yml
 # Install the conda environment
-COPY environment.yml /
-COPY . /pangolin/
 RUN conda env create --quiet -f /environment.yml && conda clean -a
-
 # Add conda installation dir to PATH (instead of doing 'conda activate')
 ENV PATH /opt/conda/envs/pangolin/bin:$PATH
+
+# Install Pangolin
+COPY . /pangolin/
 WORKDIR /pangolin/
-RUN pip install -e .
-RUN pangolin --version &> pangolin-version.txt
+RUN pip install . && rm -rf /root/.cache/pip
+RUN pangolin --version &> /pangolin-version.txt
 
 # Dump the details of the installed packages to a file for posterity
-RUN conda env export --name pangolin > pangolin.yml
+RUN conda env export --name pangolin > /pangolin.yml
+WORKDIR /tmp/