Example Scenarios

Scenario 1: Simple Application

.app.src:

{application, my_app, [
    {description, "My Application"},
    {vsn, "1.0.0"},
    {registered, []},
    {applications, [kernel, stdlib]},
    {mod, {my_app_app, []}},
    {modules, []}
]}.

After Compilation:

• ebin/my_app_app.beam exists
• ebin/my_app_sup.beam exists

Generated .app:

{application, my_app, [
    {description, "My Application"},
    {vsn, "1.0.0"},
    {registered, []},
    {applications, [kernel, stdlib]},
    {mod, {my_app_app, []}},
    {modules, [my_app_app, my_app_sup]}
]}.

Scenario 2: Git-Based Version

.app.src:

{application, my_app, [
    {description, "My Application"},
    {vsn, git},
    {applications, [kernel, stdlib]},
    {modules, []}
]}.

Git State: Tag v1.2.3, 5 commits ahead

Generated .app:

{application, my_app, [
    {description, "My Application"},
    {vsn, "1.2.3-5-gabc123"},
    {applications, [kernel, stdlib]},
    {modules, [my_app_app]}
]}.

Scenario 3: Variable Substitution

rebar.config:

{app_vars_file, "vars/build.vars"}.

vars/build.vars:

{build_time, "2024-01-15T10:30:00Z"}.
{build_user, "jenkins"}.

.app.src:

{application, my_app, [
    {vsn, "1.0.0"},
    {applications, [kernel, stdlib]},
    {modules, []},
    {env, [
        {build_time, build_time},
        {build_user, build_user}
    ]}
]}.

Generated .app:

{application, my_app, [
    {vsn, "1.0.0"},
    {applications, [kernel, stdlib]},
    {modules, [my_app_app]},
    {env, [
        {build_time, "2024-01-15T10:30:00Z"},
        {build_user, "jenkins"}
    ]}
]}.

Scenario 4: Extra Source Directories

rebar.config:

{extra_src_dirs, ["test"]}.

Files:

• src/my_app.erl → ebin/my_app.beam
• test/my_test.erl → _build/test/extras/test/my_test.beam

Generated .app (modules list):

{modules, [my_app]}  % my_test NOT included

Scenario 5: Dynamic .app.src.script

File: src/my_app.app.src.script

%% Dynamic version based on environment
Version = case os:getenv("RELEASE_VERSION") of
    false -> "dev";
    V -> V
end,

%% Dynamic applications based on profile
ExtraApps = case os:getenv("PROFILE") of
    "prod" -> [recon];
    _ -> []
end,

{application, my_app, [
    {description, "My App"},
    {vsn, Version},
    {applications, [kernel, stdlib | ExtraApps]},
    {modules, []}
]}.

Production Build (RELEASE_VERSION=1.0.0, PROFILE=prod):

{application, my_app, [
    {description, "My App"},
    {vsn, "1.0.0"},
    {applications, [kernel, stdlib, recon]},
    {modules, [my_app]}
]}.

Development Build (no env vars):

{application, my_app, [
    {description, "My App"},
    {vsn, "dev"},
    {applications, [kernel, stdlib]},
    {modules, [my_app]}
]}.