I have been using Docker for a while for some of my small Ruby on Rails sites and recently I realised I didn’t understand how something could be working! I am looking at this diagram:
but I am still unsure what is going on.
The background is:
- I have had a number of small Rails sites going for years.
- A while ago I decided to “Dockerise” all of them
- I created a Fedora + RoR image
- From this image I created a container for each of my sites
- I copied the appropriate Rails dir into /home in each case
- I created a nginx conf file on the host machine for each container / site
Everything has been working for a while now but just recently when I was in a hurry to update one of the sites, I updated the info in the original Rails dir on the HOST machine instead of in the dir in /home of the docker container - but it still worked!
How could this be? The way I understand a container is that it is self contained isn’t it? I think somehow I must be making some sort of compensatory mistake or something?