Commit graph

58 commits

Author SHA1 Message Date
Nicolas B. Pierron f5dfe78a1e Add overlays mechanism to Nixpkgs.
This patch add a new argument to Nixpkgs default expression named "overlays".

By default, the value of the argument is either taken from the environment variable `NIXPKGS_OVERLAYS`,
or from the directory `~/.nixpkgs/overlays/`.  If the environment variable does not name a valid directory
then this mechanism would fallback on the home directory.  If the home directory does not exists it will
fallback on an empty list of overlays.

The overlays directory should contain the list of extra Nixpkgs stages which would be used to extend the
content of Nixpkgs, with additional set of packages.  The overlays, i-e directory, files, symbolic links
are used in alphabetical order.

The simplest overlay which extends Nixpkgs with nothing looks like:

```nix
self: super: {
}
```

More refined overlays can use `super` as the basis for building new packages, and `self` as a way to query
the final result of the fix-point.

An example of overlay which extends Nixpkgs with a small set of packages can be found at:
  https://github.com/nbp/nixpkgs-mozilla/blob/nixpkgs-overlay/moz-overlay.nix

To use this file, checkout the repository and add a symbolic link to
the `moz-overlay.nix` file in `~/.nixpkgs/overlays` directory.
2017-01-16 01:17:33 +01:00
John Ericson 67ebd3161b top-level: Inherit system and platform in stage.nix not all-packages.nix
These are not packages, and so its more elegant to do this outside of
all-packages.nix.
2017-01-13 13:23:25 -05:00
David Grayson 0f33b9f7f1 top-level: Do stdenvOverrides in stage.nix even if crossSystem exists.
Instead, the cross stdenv will patch up the override field -- the complexity
is now confined to the one place it matters.
2017-01-13 13:23:25 -05:00
John Ericson 3e197f7d81 top-level: Normalize stdenv booting
Introduce new abstraction, `stdenv/booter.nix` for composing bootstraping
stages, and use it everywhere for consistency. See that file for more doc.

Stdenvs besides Linux and Darwin are completely refactored to utilize this.
Those two, due to their size and complexity, are minimally edited for
easier reviewing.

No hashes should be changed.
2017-01-13 13:23:23 -05:00
John Ericson 0ef8b69d12 top-level: Modernize stdenv.overrides giving it self and super
Document breaking change in 17.03 release notes
2017-01-13 10:36:11 -05:00
John Ericson 4751d9e5ad top-level: turn the screw
- Non-cross stdenvs are honest and assert that `crossSystem` is null

 - `crossSystem` is a mandatory argument to top-level/stage.nix, just like
   `system` and `platform`

 - Broken default arguments on stdenvs for testing are gone.

 - All stdenvs (but little-used stdenvNix) take the same arguments for easy
   testing.
2016-12-01 11:24:33 -05:00
John Ericson d240a0da1a top-level: Remove cycles: stdenv calls in top-level but not vice versa
This commit changes the dependencies of stdenv, and clean-up the stdenv
story by removing the `defaultStdenv` attribute as well as the `bootStdenv`
parameter.

Before, the final bootstrapping stage's stdenv was provided by
all-packages, which was iterating multiple times over the
top-level/default.nix expression, and non-final bootstrapping stages'
stdenvs were explicitly specified with the `bootStdenv` parameter.

Now, all stages' stdenvs are specified with the `stdenv` parameter.
For non-final bootstrapping stages, this is a small change---basically just
rename the parameter.
For the final stage, top-level/default.nix takes the chosen stdenv and
makes the final stage with it.

`allPackages` is used to make all bootstrapping stages, final and
non-final alike. It's basically the expression of `stage.nix` (along with a
few partially-applied default arguments)

Note, the make-bootstrap-tools scripts are temporarily broken
2016-11-30 19:10:59 -05:00
John Ericson 07a2b17cbf top-level: Split some of pkgs/top-level/default.nix to pkgs/top-level/stage.nix
This is preparation for the latter just building a single stage, and the
former building a package set with the bootstrapped stdenv.
2016-11-30 19:04:22 -05:00