Example Scenarios

Scenario 1: Simple Project Initialization

Setup:

my_app/
├── rebar.config
└── src/
    └── my_app.erl

rebar.config:

{erl_opts, [debug_info]}.

Execution: rebar3 compile

Flow:

1. Read rebar.config → [{erl_opts, [debug_info]}]
2. No rebar.lock → empty lock
3. Create state with opts
4. Apply default profile
5. No plugins to install
6. Register built-in providers
7. Dispatch to compile command

Result: State initialized with debug_info enabled

Scenario 2: Project with Test Profile

rebar.config:

{erl_opts, [debug_info]}.
{profiles, [
    {test, [
        {deps, [meck]},
        {erl_opts, [nowarn_export_all]}
    ]}
]}.

Execution: rebar3 as test compile

Flow:

1. Load base config
2. Apply default profile
3. Apply test profile:
   • Add meck to deps
   • Add nowarn_export_all to erl_opts
4. Result: {erl_opts, [nowarn_export_all, debug_info]}

Scenario 3: Global Plugin Installation

~/.config/rebar3/rebar.config:

{plugins, [rebar3_hex]}.

Execution: rebar3 compile (in any project)

Flow:

1. Load project config
2. Detect global config exists
3. Load global config
4. Install rebar3_hex plugin globally
5. Register hex providers (publish, etc.)
6. Proceed with project compilation

Result: Hex commands available in all projects

Scenario 4: Environment Variable Override

rebar.config:

{erl_opts, [debug_info]}.
{profiles, [
    {prod, [{erl_opts, [no_debug_info]}]}
]}.

Execution: REBAR_PROFILE=prod rebar3 compile

Flow:

1. Load base config
2. Detect REBAR_PROFILE=prod
3. Apply prod profile
4. Result: {erl_opts, [no_debug_info]}

Scenario 5: Offline Mode

Execution: rebar3 compile --offline

Flow:

1. Parse --offline flag
2. Set REBAR_OFFLINE=1 environment variable
3. Skip starting ssl and inets
4. Set offline flag in state
5. Later stages skip network operations

Impact: Dependencies must already be cached