When doing a hot upgrade with relup release handling, the application parameters are gone. [JIRA: RIAK-3081]

[jvdvleuten]

When doing a hot upgrade, all application parameters are gone. When using the correct .conf file, it still misses some parameters because they are set using application:set_env/3. After the upgrade, the riak_core application is thus broken.

See this quote on the release handling manual page:

http://erlang.org/doc/design_principles/release_handling.html#id84983

Specifically, the application configuration parameters are automatically updated according to (in increasing priority order):

The data in the boot script, fetched from the new application resource file App.app
The new sys.config
Command-line arguments -App Par Val
This means that parameter values set in the other system configuration files and values set using application:set_env/3 are disregarded.

Application parameters are set and appended when starting riak_core here:

https://github.com/basho/riak_core/blob/develop/src/riak_core_app.erl#L42

I have now manually created this function and exported it, mimicking the function body:

add_bucket_defaults() ->
    %% add these defaults now to supplement the set that may have been
    %% configured in app.config
    riak_core_bucket:append_bucket_defaults(riak_core_bucket_type:defaults(default_type)),
    ok.

I then call it in my relup file as follows:

{apply,{my_app,add_bucket_defaults,[]}}

Any other more elegant ideas? Am I missing something here?