We were planning to upgrade my rails application which is a monolith application and having around a million LOC. What would be the best way to upgrade?
The following are the options
1) 3.2 -> 5.2 (Separate branch running for a long time, Total mess up)
2) 3.2->4.2 ->5.2 ((Separate branch running for a short time)
3) 3.2->4.0->4.1->4.2->5.0->5.1->5.2(Running in master periodically, But we may need to write code in particular version which may become obsolete in the next coming version)
I am planning to follow approach 3, but I am not sure which part is added in version (4.0 to 5.1) and removed in(4.2 to 5.2).
Did anyone did rails upgrade for their application, what was the approach.
PS: I saw many posts around this, but nothing solid.