Fix build with RabbitMQ master and 3.8.x

[dumbbell]

Two changes are required for that:

1. An update to rabbitmq-components.mk to have the correct fetch method for ra
2. Getting rid of direct uses of the #internal_user{} record because it was made private.

[simmel]

Thank you so much for the PR!

Can't get it to build though, but I'm probably doing something wrong:

onrain:~/code/rabbitmq-auth-backend-kerberosᛘremotes/origin/pr/10$ make
 DEP    rabbit_common (origin/pr/10)
 DEP    rabbit (origin/pr/10)
make[1]: Entering directory '/home/simmel/code/rabbitmq-auth-backend-kerberos/deps/rabbit_common'
 DEP    rabbitmq_codegen (origin/pr/10)
 DEP    lager (3.8.0)
No beam files found.
escript: exception error: undefined function make:files/2
  in function  erl_eval:do_apply/6 (erl_eval.erl, line 680)
  in call from erl_eval:expr/5 (erl_eval.erl, line 273)
  in call from escript:eval_exprs/5 (escript.erl, line 872)
  in call from erl_eval:local_func/6 (erl_eval.erl, line 567)
  in call from escript:interpret/4 (escript.erl, line 788)
  in call from escript:start/1 (escript.erl, line 277)
  in call from init:start_em/1
/home/simmel/code/rabbitmq-auth-backend-kerberos/deps/rabbit_common
{"init terminating in do_boot",{undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{file,"erl_eval.erl"},{line,680}]},{erl_eval,exprs,5,[{file,"erl_eval.erl"},{line,126}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{_},{_}]},{erl_eval,exprs,5,[{_},{_}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]})

Crash dump is being written to: erl_crash.dump...done
 DEP    jsx (2.11.0)
{"init terminating in do_boot",{undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{file,"erl_eval.erl"},{line,680}]},{erl_eval,exprs,5,[{file,"erl_eval.erl"},{line,126}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{_},{_}]},{erl_eval,exprs,5,[{_},{_}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]})

Crash dump is being written to: erl_crash.dump...done
 DEP    ranch (1.7.1)
 DEP    recon (2.5.1)
{"init terminating in do_boot",{undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{file,"erl_eval.erl"},{line,680}]},{erl_eval,exprs,5,[{file,"erl_eval.erl"},{line,126}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{_},{_}]},{erl_eval,exprs,5,[{_},{_}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]})

Crash dump is being written to: erl_crash.dump...done
 DEP    credentials_obfuscation (2.2.0)
{"init terminating in do_boot",{undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{file,"erl_eval.erl"},{line,680}]},{erl_eval,exprs,5,[{file,"erl_eval.erl"},{line,126}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({undef,[{rmemo,start,[],[]},{erl_eval,do_apply,6,[{_},{_}]},{erl_eval,exprs,5,[{_},{_}]},{init,start_it,1,[]},{init,start_em,1,[]},{init,do_boot,3,[]}]})

Crash dump is being written to: erl_crash.dump...done
make[2]: Entering directory '/home/simmel/code/rabbitmq-auth-backend-kerberos/deps/rabbitmq_codegen'
make[2]: Leaving directory '/home/simmel/code/rabbitmq-auth-backend-kerberos/deps/rabbitmq_codegen'
Error: No Makefile to build dependency /home/simmel/code/rabbitmq-auth-backend-kerberos/deps/lager.
make[1]: *** [erlang.mk:4512: deps] Error 2
make[1]: Leaving directory '/home/simmel/code/rabbitmq-auth-backend-kerberos/deps/rabbit_common'
make: *** [erlang.mk:4512: deps] Error 2
onrain:~/code/rabbitmq-auth-backend-kerberosᛘremotes/origin/pr/10$ !2!

[simmel]

Uh, scratch that, I'm just bad at following instructions! I'll report back.

[simmel]

What are your thoughts of specifying dependency_version_requirements?

[dumbbell]

Crap, I see the internal_user module didn't make it to a 3.8.x release yet... So with my patch, the plugin is not compatible with any release of RabbitMQ for now. Let me talk to the developer who worked on the change to #internal_user{}.

[dumbbell]

The new API was backported to the 3.8.x release branch, so it will be part of the next release. The plugin could advertise compatibility with RabbitMQ 3.8.10.

Unfortunately, the way it was backported makes it impossible to have the same plugin compatible with 3.8.10+ and previous releases.

[simmel]

Just to clarify: that would mean that no version, past or future, of this plugin will work with any release within >=3.8.0 <3.8.10? I'm guessing this plugin isn't that well used tbh so I suspect that is OK = )

…

On Mon, 2020-10-19 at 07:08:15 -0700, Jean-Sébastien Pédron wrote: The new API was backported to the 3.8.x release branch, so it will be part of the next release. The plugin could advertise compatibility with RabbitMQ 3.8.10. Unfortunately, the way it was backported makes it impossible to have the same plugin compatible with 3.8.10+ and previous releases. -- You are receiving this because you commented. Reply to this email directly or view it on GitHub: #10 (comment)

[dumbbell]

I believe the plugin with this branch, but without the 3rd commit, will work with RabbitMQ 3.8.0 to 3.8.9 included.

With the 3rd commit in this branch, it is only compatible with 3.8.10.

The internal_user API was poorly backported to the 3.8.x branch, and it's impossible to have the same codebase compatible with all versions of RabbitMQ.

[simmel]

Well that’s fine. Not many users of the plug-in and the ones which use it can read the README. Dear lazyweb, do you know what the oldest version of RabbitMQ that is supported by Pivotal?

…

On 20 Oct 2020, at 14:20, Jean-Sébastien Pédron ***@***.***> wrote:  I believe the plugin with this branch, but without the 3rd commit, will work with RabbitMQ 3.8.0 to 3.8.9 included. With the 3rd commit in this branch, it is only compatible with 3.8.10. The internal_user API was poorly backported to the 3.8.x branch, and it's impossible to have the same codebase compatible with all versions of RabbitMQ. — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

[simmel]

Sorry for lagging with this PR @dumbbell, it's been a hectic autumn. Do you know how I can build a plugin towards a specific version of RabbitMQ? I searched make help but didn't see anything and nor did the docs I could find.

[dumbbell]

There is no documented way, but a good solution is to use the current_rmq_ref on the command line:

make current_rmq_ref=v3.8.9 dist