rebar: Missing application directory

Question

I'm testing rebar on

• Windows 8 64Bis
• Erlang 64bits R15B02

I've compiled rebar from github code and created a basic app

$ mkdir testapp; cd testapp
$ mkdir rel
$ rebar create-app appid=testapp
$ echo "{sub_dirs, ["rel"]}." > rebar.config
$ cd rel
$ rebar create-node nodeid=testnode
$ cd -
$ rebar compile
$ rebar generate    
ERROR: generate failed while processing testapp/rel: {'EXIT',{{badmatch,{error,"testapp: : Missing application directory."}
...

I'm reading the reltool documentation but i cant found anything about application dir the only relevant option is incl_cond but is defined by default by rebar command

src/testapp.app.src

{application, testapp,
 [
  {description, ""},
  {vsn, "1"},
  {registered, []},
  {applications, [
                  kernel,
                  stdlib
                 ]},
  {mod, { testapp_app, []}},
  {env, []}
 ]}.

rel/reltool.config

{sys, [
       {lib_dirs, []},
       {erts, [{mod_cond, derived}, {app_file, strip}]},
       {app_file, strip},
       {rel, "testapp", "1",
        [
         kernel,
         stdlib,
         sasl,
         testapp
        ]},
       {rel, "start_clean", "",
        [
         kernel,
         stdlib
        ]},
       {boot_rel, "testapp"},
       {profile, embedded},
       {incl_cond, derived},
       {mod_cond, derived},
       {excl_archive_filters, [".*"]}, %% Do not archive built libs
       {excl_sys_filters, ["^bin/.*", "^erts.*/bin/(dialyzer|typer)",
                           "^erts.*/(doc|info|include|lib|man|src)"]},
       {excl_app_filters, ["\.gitignore"]},
       {app, testapp, [{mod_cond, app}, {incl_cond, include}]}
      ]}.

{target_dir, "testapp"}.

{overlay, [
           {mkdir, "log/sasl"},
           {copy, "files/erl", "\{\{erts_vsn\}\}/bin/erl"},
           {copy, "files/nodetool", "\{\{erts_vsn\}\}/bin/nodetool"},
           {copy, "files/testapp", "bin/testapp"},
           {copy, "files/testapp.cmd", "bin/testapp.cmd"},
           {copy, "files/start_erl.cmd", "bin/start_erl.cmd"},
           {copy, "files/install_upgrade.escript", "bin/install_upgrade.escript"},
           {copy, "files/sys.config", "releases/\{\{rel_vsn\}\}/sys.config"},
           {copy, "files/vm.args", "releases/\{\{rel_vsn\}\}/vm.args"}
          ]}.

Answer 1

In my case I had to modify the default rel/reltool.config line

   {lib_dirs, []},

to

   {lib_dirs, ["../../"]},

Where the layout of my project is:

Makefile
ebin/   
rebar.config
rel/    
src/

Answer 2

This might help you . (quoted below in case the original link disappears)

Not exactly sure what's the reason for that change for versions following R15B01 though.

Thanks to Siri, reltool in R15B01 includes a really useful feature.

Many Erlang projects are using the following structure:
./src/foo.app.src
./src/foo.erl
./rel/reltool.config

When you wanted to reference the application foo in rel/reltool.config, you previously had three options:
* project-local libs/ or apps/ directory
* unsafe {lib_dirs, "../.."} reltool.config setting
* rebar_reltool_link fake_lib_dir plugin

Starting with R15B01 all you have to do now is specify
{app, foo, [{incl_cond, include}, {lib_dir, ".."}]}
in reltool.config for applications not in lib_dirs.

Although R15B01 is still in development, this feature is complete and can be used in the otp.git maint branch.

Answer 3

Refer this guideline, https://github.com/rebar/rebar/wiki/Release-handling

If you're using R15B01 or newer change,

{app, exemplar, [{mod_cond, app}, {incl_cond, include}, {lib_dir, ".."}]}

above way of mentioning path solved the application directory not found issue for me.