Large scale CI upgrade

Hey all,

I've been working on a CI project nearly non-stop for 7 years.  The Program is in use internally, on a daily basis by several hundred people.

Best practice has not been followed over the years - Ubuntu version is old, PHP version is ancient, CI version is a grumpy old man.

I want to gradually transition everything on to a new server, fully updated.  Because a lot of the code will not work due to deprication and such, I was thinking of having two domains:

- new.program.com
- old.program.com

I was thinking that I could transition the code one module at a time - there are about 150 modules, and transitioning will be long and tedious, and development still has to be ongoing.  After I am able to integrate module1 into the new server - any references on the old server could redirect the new server, and vice versa.

Does this make sense?  Any suggestions? Is there a more logical way of doing this?

Thanks!

If you are transitioning one module at a time - how do you know which version to call (the old or the new?)

What version CI are you using?

How will you handle the database? will both versions of CI talk to the one DB?

Sounds like it's gonna be a nightmare, and it would be very difficult to get anything but general advice here.

May the force be with you!

I'd consider setting up the new server (new Ubuntu, Apache, PHP, db) but keep it "off line" as far as your intranet users are concerned.

Use a copy of the db so you can fowl the data all you like an not mess up real operations.

Put your old project in there and work through it step-by-step per the upgrade instructions. The go back a use test each module one at a time.

When the new server is deemed ready you can take the old on off line and name the new one live.

Hopefully the users will never know the difference.

Thanks everyone,

One Year later... It has mostly been implemented!

In the end I just locked down the production code, and hammered away at creating a new version. It was ugly.
After about a month of correcting and fixing the code, it went live

All the wonderful bugs I missed have mostly been reported and fixed up since.