[erlang-questions] starting an app with an app.config file

[Roberto Ostinelli]

Dear list,

I have an application set up with the standard structure:

-- myproject
   rebar.config
   app.config
   |-- apps
       |-- myapp
           |--src
              ...
           |--test
              myapp_SUITE.erl
   |-- deps
       |-- dep1
       |-- dep2
   |-- ...

Please note app.config in there. Everything perfectly fine if I start myapp.

However, I'm trying to use Common Tests, and I start myapp in myapp_SUITE.erl during init:

init_per_suite(Config) ->

ok = application:start(myapp),

Config.

During startup, myapp tries to access config variables:

{ok, Port} = application:get_env(myapp, port),

This crashes in test, because application:get_env(myapp, port) returns undefined. This basically means that myapp does not load app.config.

How can I solve this?

Thank you,

r.

[Roberto Ostinelli]

To extend: I can ensure that app.config is used:

• when in development mode, by configuring it manually:

erl -pa apps/*/ebin -pa deps/*/ebin \

-boot start_sasl \

-config app \

-s myapp

• when it is packaged as a release (i believe this can be managed by reltool)

But how can I set myapp to use it in common tests?

[Andrew Gopienko]

From my eunit tests

    SaslSpec = [{errlog_type, error}],
    case application:load({application,sasl,SaslSpec}) of
  {error,{already_loaded,_}} -> ok;
  ok ->
      ok = application:start(sasl),

2012/10/15 Roberto Ostinelli <rob...@widetag.com>

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[Roberto Ostinelli]

What has this to do with my question?

My question is how can I use the same app.config file when I start an application from Common Tests.

[Andrew Gopienko]

Just read your config file and set env with application:load before application:start

2012/10/15 Roberto Ostinelli <rob...@widetag.com>

[Roberto Ostinelli]

Oh I understand now.

Thank you Andrew, will try that.

r.

[Roberto Ostinelli]

Hi,

this isn't working. From the docs:

load(AppDescr) -> ok | {error, Reason}

load(AppDescr, Distributed) -> ok | {error, Reason}

So application:load/2 actually is not reading from a config file.

Any other ideas?

r.

[Jesse Gumm]

Hi Roberto,

What about adding the app(s) to your appname.rel script in release/x.y.z and then using systools:make_script to generate the boot script.

That seems to work for me, anyway

-Jesse

--
Jesse Gumm
Owner, Sigma Star Systems
414.940.4866 || sigma-star.com || @jessegumm

[Motiejus Jakštys]

On Sat, Oct 20, 2012 at 10:00 PM, Roberto Ostinelli <rob...@widetag.com> wrote:
> Hi,
>
> this isn't working. From the docs:
>
> load(AppDescr) -> ok | {error, Reason}
> load(AppDescr, Distributed) -> ok | {error, Reason}
>
> So application:load/2 actually is not reading from a config file.
>
> Any other ideas?

{ok, Config} = file:consult(File),
[application:set_env(myapp, K, V) | {K, V} <- Config].

Not tested.

Config might have to be [Config], you should try this out.

--
Motiejus Jakštys

[Roberto Ostinelli]

Hi Motiejus,

I'm doing something similar. It just feels weird. (:

r.

[Phillip Toland]

If you put an app.config file into the test directory, rebar will pick
it up. If you don't want to have two app.config files, then you can
use the ct_extra_params option in rebar.config. The value of that
option will be passed on the command line of the beam process that
runs the tests, so you could pass in something like "-config
app.config" and have it use the existing config file.

~p

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