add Dockerfile and docs for running from container

Dockerfile

@@ -0,0 +1,7 @@
+FROM node:11
+
+ENV NPM_CONFIG_PREFIX=/home/node/.npm-global
+ENV PATH=$PATH:/home/node/.npm-global/bin
+
+USER node
+RUN npm install -g mobility-metrics

README.md

@@ -125,6 +125,38 @@ The CLI is responsible for downloading raw data, running aggregation and reports
 mobility-metrics --config ./example/example.json --public ./public --cache ./cache --day 2019-07-20;
 ```
 
+## Docker
+
+Docker is supported, and is recommended when installation is challenging on bespoke systems that fail when installing dependencies, such as OSRM.
+
+### Building a docker image
+
+```sh
+# clone repo
+git clone [email protected]:sharedstreets/mobility-metrics.git
+cd mobility-metrics
+
+# build image
+docker build --tag mobility-metrics-image .
+```
+
+### Running mobility-metrics from docker image
+
+Once you have a docker image built, use mobility-metrics CLI from within the image using `docker run`. In this example, a config file exists in the current directory, which mobility-metrics can read using the mounted volume.
+
+```sh
+docker run -it --rm \
+-v $PWD:/data/ \ # mount current working directory to image volume
+mobility-metrics-image \
+  mobility-metrics \
+    --config /data/config.json \
+    --public /data/public \
+    --cache /data/cache \
+    --startDay 2019-09-20 \
+    --endDay 2019-09-20 \
+    --reportDay 2019-09-20;
+```
+
 ## Serving API
 
 The metrics data and reports generated by the mobility-metrics CLI are intended to be served from a static HTTP server, such as apache, nginx, or a public HTTP service like netifly or Github Pages. See the gh-pages branch of this repository to see how the demo for this tool is hosted using simulated data in Nashville, TN.
@@ -176,5 +208,3 @@ Runs a linter, prettier, and auto-formats code to meet consistent style, while c
 ```sh
 npm run lint
 ```
-
-