Application Discovery

Purpose

The application discovery stage scans project directories to locate all OTP applications, parses their application resource files (.app, .app.src, .app.src.script, or mix.exs), extracts application metadata, validates application structure, and prepares application information records for compilation. This stage determines which applications are part of the project and which are dependencies.

When It Executes

This stage executes early in the build process via the app_discovery provider, which is a dependency of install_deps. It runs:

• After Initialization & Configuration
• Before Dependency Resolution & Locking
• On every rebar3 compile invocation
• Whenever project structure changes

Prerequisites

• State initialized with configuration
• Project root directory determined
• Configuration specifying lib_dirs and src_dirs
• File system accessible

Outputs

• List of project applications (rebar_state:project_apps/1)
• Parsed dependencies per profile ({parsed_deps, Profile} in state)
• Application info records for each discovered app
• Determination of top-level app vs umbrella project structure