At the moment, we move a bit the VMs (Virtual Machines) powering up our PaaS (Platform as a Service). The platform has one virtual machine receiving the code updates and then the Cheméo application is updated from it. The application itself is running on another VM behind the web server. The work we do is to disconnect the web server from the application. So, at the end we get :
- 1 VM with the web server answering your requests;
- 2 VMs with the Cheméo application servers — they are doing the work like pulling the data out of the database;
- 1 VM hosting the code and building the new application code which is then deployed on the previous 2 VMs.
This seams a bit complicated but the advantage is that it is very easy to add new application server VM to handle more requests.
Anyway, the split requires moving component here and there and synchronizing the data, this does not work always as expected and this why, one thing you can expect for sure is a bit of downtime during the next few days.