Went to the Docker Meet-up tonight. The Jenkins-in-Docker talk gave me a couple ideas. One should be a solution to my having to separately support each and every instance of my web-based Docker management tool (I even have Docker installed on RPi's and a number of VMs). If I understand it correctly, using the Docker-out-of-Docker method (as opposed to Docker-in-Docker), I'll just need to maintain one Dockerfile and I can deploy the web tool as needed/desired. I'm thinking that I'll need some sort of automatic proxy (like what jwilder has done.
I'm also wondering if a single instance of the web-front end can control ALL of the Docker instances. Something for later I think.
The (on demand) scalable Jenkins-in-Docker caused me to look at Sphinx-in-Docker. Luckily, the Sphinx site already has an article about running Sphinxsearch (at least searchd) in Docker containers. This will probably take me the rest of the year to figure out but it's piqued my interest. The scary part is that it'll probably involve using NGINX as a reverse proxy for Docker Swarm Clusters (minus the DigitalOcean piece). Unless someone has already figured this out (and hasn't attached it to proprietary infrastructure), I figure it'll take a couple months to get working. In short, it'll be a lengthy "learning opportunity".
Will keep y'all posted.