updated Dockerfile based on feedback to use conda for wget and vim installs instead of OS package manager

Author: jdye64

Dockerfile

@@ -1,39 +1,37 @@
 FROM python:3.7.5-slim
 USER root
+SHELL ["/bin/bash", "--login", "-c"]
 
 ENV DEBIAN_FRONTEND noninteractive
 ENV SCALA_VERSION 2.11
 ENV KAFKA_VERSION 2.3.0
 ENV KAFKA_HOME /opt/kafka_"$SCALA_VERSION"-"$KAFKA_VERSION"
 
-# Install system dependencies and convenience utilities
-RUN apt-get update -y && \
-    apt-get install -y wget \
-                       vim && \
-    apt-get clean
-
 # Install conda
 ADD https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh /miniconda.sh
 RUN sh /miniconda.sh -b -p /conda && /conda/bin/conda update -n base conda
-ENV PATH=${PATH}:/conda/bin
-SHELL ["/bin/bash", "-c"]
+RUN echo "PATH=${PATH}:/conda/bin" >> ~/.bashrc
 
 # Add Streamz source code to the build context
 ADD . /streamz/.
 
 # Create the conda environment
 RUN conda env create --name streamz-dev -f /streamz/conda/environments/streamz_dev.yml
+RUN conda init bash
+
+# Ensures subsequent RUN commands do not need the "conda activate streamz_dev" command
+RUN echo "conda activate streamz_dev" >> ~/.bashrc
 
 # Build streamz from source
-RUN source activate streamz-dev && \
-    cd /streamz && \
+RUN cd /streamz && \
     python setup.py install
 
 # Install optional dependencies in the conda environment
-RUN source activate streamz-dev && \
-    conda install -c conda-forge jupyterlab \
+RUN conda install -c conda-forge jupyterlab \
                                  numpy \
-                                 pandas
+                                 pandas \
+                                 wget \
+                                 vim
 
 # Install Kafka
 RUN wget -q http://www.gtlib.gatech.edu/pub/apache/kafka/2.3.0/kafka_2.11-2.3.0.tgz -O /tmp/kafka_"$SCALA_VERSION"-"$KAFKA_VERSION".tgz && \