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Design sec improvements

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Doron Behar 2020-08-16 15:44:17 +03:00
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rfcs/0075-declarative-wrappers.md
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@ -191,8 +191,8 @@ need feedback regarding whether `gdb` will play nice with this.
This issue may not directly relate to declarative wrappers, and it is already
addressed in @FRidh's [pull 95569](https://github.com/NixOS/nixpkgs/pull/95569), but perhaps
both ideas could be integrated into an alternative, simpler creation method of
binary wrappers. See
[comment](https://github.com/NixOS/nixpkgs/pull/95569#issuecomment-674508806)
binary wrappers. See [my
comment](https://github.com/NixOS/nixpkgs/pull/95569#issuecomment-674508806).
# Detailed design
[design]: #detailed-design
@ -200,13 +200,16 @@ binary wrappers. See
The current design is roughly implemented at
[pull 85103](https://github.com/NixOS/nixpkgs/pull/85103) .
The idea is to have a Nix function, called `wrapGeneric` with an interface
similar to [`wrapMpv`](https://github.com/NixOS/nixpkgs/blob/a5985162e31587ae04ddc65c4e06146c2aff104c/pkgs/applications/video/mpv/wrapper.nix#L9-L23) and [`wrapNeovim`](https://github.com/NixOS/nixpkgs/blob/a5985162e31587ae04ddc65c4e06146c2aff104c/pkgs/applications/editors/neovim/wrapper.nix#L11-L24) which will accept a single derivation or
an array of them and it'll wrap all of their executables with the proper
environment, based on their inputs.
The idea is to have a Nix function, let us call it `wrapGeneric`, with an
interface similar to
[`wrapMpv`](https://github.com/NixOS/nixpkgs/blob/a5985162e31587ae04ddc65c4e06146c2aff104c/pkgs/applications/video/mpv/wrapper.nix#L9-L23)
and
[`wrapNeovim`](https://github.com/NixOS/nixpkgs/blob/a5985162e31587ae04ddc65c4e06146c2aff104c/pkgs/applications/editors/neovim/wrapper.nix#L11-L24)
which will accept a single derivation or an array of them and it'll wrap all of
their executables with the proper environment, based on their inputs.
`wrapGeneric` should iterate recursively all `buildInputs` and
`propagatedBuildInputs` of the input derivations, and construct an attrset with
`propagatedBuildInputs` of the input derivation(s), and construct an attrset with
which it'll calculate the necessary environment of the executables. Then either
via `wrapProgram` or a better method, it'll create the wrappers.
@ -218,20 +221,16 @@ and with this information at hand, construct the necessary wrapper.
In order for `wrapGenric` to know all of this information about our packaged
libraries - the information about runtime env, we need to write in the
`passthru`s of these libraries, what env vars they need.
This Nix function, let us call it `wrapGeneric`, should iterate recursively all
`buildInputs` and `propagatedBuildInputs` of a given derivation, and decide
what environment this derivation will need to run. Such information was added
in the [POC pull's
`passthru`s of these libraries, what env vars they need. Such information was
added in the POC pull at [commit
@6283f15](https://github.com/NixOS/nixpkgs/pull/85103/commits/6283f15bb9b65af64571a78b039115807dcc2958).
Additional features / improvements are [already
available](https://github.com/NixOS/nixpkgs/pull/85103#issuecomment-614195666)
in the POC pull. For example:
- It should be impossible for multi-value env vars to have duplicates, as
that's guaranteed by Nix' behavior when constructing arrays.
- It should be **impossible** for multi-value env vars to have duplicates, as
that's guaranteed by Nix' behavior when constructing arrays / attrsets.
- Asking the wrapper creator to use more links and less colon-separated values
in env vars - should help avoid what [pull
84689](https://github.com/NixOS/nixpkgs/pull/84689) fixed.
@ -242,7 +241,7 @@ in the POC pull. For example:
All examples are copied from and based on the [POC
pull](https://github.com/NixOS/nixpkgs/pull/85103).
The new method of creating a python environment:
Here's a new method of creating a python environment:
```nix
my-python-env = wrapGeneric python3 {