Up and running in a few minutes
You have Docker installed already, right? Good.
docker run -d -p 3000:3000 \ --name=grafana \ -e 'GF_INSTALL_PLUGINS=grafana-simple-json-datasource' \ grafana/grafana pip install flask python index.py
Now go to http://localhost:3000 and log into Grafana with admin:admin.
Next create a datasource in Grafana with type="SimpleJson" and URL="http://docker.for.mac.localhost:5000".
The above works with Docker for Mac, if you are using another OS then the hostname will need to be different in order to access the locally running Flask server.
Now you can create a dashboard with a graph panel, use the simplejson datasource you created, and interact with the Flask server you started.