Dependency Acquisition

Purpose

The dependency acquisition stage fetches dependencies from their respective sources (Hex package registry, Git repositories, Mercurial repositories, local checkouts), verifies their integrity, extracts them to the appropriate locations, and prepares them for compilation. This stage ensures all required dependencies are available locally before compilation begins.

When It Executes

This stage executes as part of the dependency resolution process in Dependency Resolution & Locking, specifically within the update_unseen_dep/9 function via the maybe_fetch/5 call. It runs during:

• install_deps provider execution
• First compilation when dependencies aren't cached
• When dependencies need updating
• After modifying rebar.config dependencies

Prerequisites

• Dependencies resolved with specific versions/refs
• Source information available (Hex, Git URL, etc.)
• Network access (unless offline mode or dependencies cached)
• Git/Mercurial tools installed (for VCS dependencies)

Outputs

• Dependencies downloaded to _build/PROFILE/lib/DEPNAME/
• Dependency configurations parsed and validated
• Application info updated with actual dependency structure
• Dependencies ready for compilation