docker tag and pip3 fixes; add a readme

docker/README.md

@@ -0,0 +1,16 @@
+# Instructions
+
+Build all docker images, in order:
+
+```bash
+(cd ubuntu-boost-tbb && exec build.sh)
+(cd ubuntu-gtsam && exec build.sh)
+(cd ubuntu-gtsam-python && exec build.sh)
+(cd ubuntu-gtsam-python-vnc && exec build.sh)
+```
+
+Then launch with: 
+
+    docker run dellaert/ubuntu-gtsam-python-vnc:bionic
+
+

docker/ubuntu-boost-tbb/build.sh

@@ -0,0 +1,3 @@
+# Build command for Docker image
+# TODO(dellaert): use docker compose and/or cmake
+docker build --no-cache -t dellaert/ubuntu-boost-tbb:bionic .

docker/ubuntu-gtsam-python-vnc/Dockerfile

@@ -1,12 +1,12 @@
 # This GTSAM image connects to the host X-server via VNC to provide a Graphical User Interface for interaction.
 
 # Get the base Ubuntu/GTSAM image from Docker Hub
-FROM dellaert/ubuntu-gtsam-python:latest
+FROM dellaert/ubuntu-gtsam-python:bionic
 
 # Things needed to get a python GUI
 ENV DEBIAN_FRONTEND noninteractive
 RUN apt install -y python-tk
-RUN pip install matplotlib
+RUN python3 -m pip install matplotlib
 
 # Install a VNC X-server, Frame buffer, and windows manager
 RUN apt install -y x11vnc xvfb fluxbox

docker/ubuntu-gtsam-python/Dockerfile

@@ -1,7 +1,7 @@
 #  GTSAM Ubuntu image with Python wrapper support.
 
 # Get the base Ubuntu/GTSAM image from Docker Hub
-FROM dellaert/ubuntu-gtsam:latest
+FROM dellaert/ubuntu-gtsam:bionic
 
 # Install pip
 RUN apt-get install -y python3-pip python3-dev

docker/ubuntu-gtsam/Dockerfile

@@ -1,7 +1,7 @@
 # Ubuntu image with GTSAM installed. Configured with  Boost and TBB support.
 
 # Get the base Ubuntu image from Docker Hub
-FROM dellaert/ubuntu-boost-tbb:latest
+FROM dellaert/ubuntu-boost-tbb:bionic
 
 # Install git
 RUN apt-get update && \