[erlang-questions] Hot code upgrade

[Grzegorz Junka]

On 30/01/2017 08:39, Arun wrote:
> Hi,
>
>     I am trying to upgrade my application using rebar3 hot code 
> upgrade feature from version 0.0.1 to 0.0.2 and my application 
> consists of around 20 modules, the difference between current version 
> and the new version is that one new module got added and one existing 
> module code has been modified. My doubt is that, in the appup file we 
> have to give list of instructions to upgrade and downgrade software 
> between different versions, is it mandatory that all 20 modules has to 
> be mentioned in the instructions or the modules which are added or 
> modified only need to be mentioned. ?
>
> Can anybody assist me on this

Not sure how it works in rebar but usually you don't need to create the 
relup file yourself. I usually use systools:make_relup. 
http://erlang.org/doc/man/systools.html
You give it two versions of the release files and the location of the 
applications and it creates the instructions for you. It is smart enough 
to figure out which modules have been removed/added or which 
applications have to be stopped/started during the release upgrade.

This chapter explains that in more details:

http://learnyousomeerlang.com/relups

Greg