Find the source code here:
Run it up from Docker Hub
$ docker run -it -p 3000:3000 elasticbrains/pageflow:0.1
Then Pageflow will be installed, this could take a while.
Wait until you see the RoR Output that the Server has started, which looks something like this:
=> Booting WEBrick => Rails 4.2.8 application starting in development on http://0.0.0.0:3000 => Run `rails server -h` for more startup options => Ctrl-C to shutdown server [2017-06-14 14:15:42] INFO WEBrick 1.3.1 [2017-06-14 14:15:42] INFO ruby 2.3.4 (2017-03-30) [x86_64-linux] [2017-06-14 14:15:42] INFO WEBrick::HTTPServer#start: pid=24 port=3000
now you should be able to call it by http://localhost:3000
The first Request to Pageflow will also take about 10 seconds, because pageflow is buidling some stuff i think