5.4 Nix build phases: enable, disable, and override them

Every stdenv.mkDerivation build runs through fixed phases: unpack, patch, configure, build, check, install, fixup, and two more. This lesson maps out all nine Nix build phases, which seven matter, which two you can forget, and how each one can be enabled, disabled, overridden, or extended. It also clears up a small mystery: why your tests silently never ran.

In this video

• All nine build phases in order, and what each one is responsible for
• The switches that turn phases off, and the one phase that is off by default
• Why doCheck breaks the naming pattern of the other flags, and a memory trick so you never mix it up
• Live demo: the same package built with and without its test suite, and the one line that makes the difference
• Hooks like postInstall: keeping the default behavior and running your own snippet around it

After this lesson

You can read the phase overrides in any nixpkgs package fluently, and you know exactly which switch to flip when a build does too much or too little.