Edge Cases

No rebar.config File

Behavior: rebar3 uses built-in defaults

Impact:

• No dependencies
• Default compiler options
• Standard directory layout expected

Empty rebar.config

Behavior: Treated same as missing file

Impact: Uses all defaults

rebar.config.script

Behavior: If rebar.config.script exists, it's evaluated as Erlang code

Purpose: Dynamic configuration generation

Example:

CONFIG1 = case os:getenv("ENV") of
    "prod" -> [{erl_opts, [no_debug_info]}];
    _ -> []
end,
CONFIG1 ++ CONFIG.

Global Config Without Local Config

Behavior: Global config provides base configuration

Use Case: Setting up a new project with global plugins available

Multiple Profiles Applied

Behavior: Profiles merge in order, later values override earlier

Example:

rebar3 as test,custom compile

Applies profiles: default → test → custom

REBAR_PROFILE Environment Variable with as Command

Behavior: Environment variable overrides are replaced by as profiles

Recommendation: Use as command instead of environment variable