tjh.dev
Clone of https://github.com/NixOS/nixpkgs.git (to stress-test knotserver)
1{ replaceVarsWith }:
2
3/**
4 `replaceVars` is a wrapper around the [bash function `substitute`](https://nixos.org/manual/nixpkgs/stable/#fun-substitute)
5 in the stdenv. It allows for terse replacement of names in the specified path, while checking
6 for common mistakes such as naming a replacement that does nothing or forgetting a variable which
7 needs to be replaced.
8
9 As with the [`--subst-var-by`](https://nixos.org/manual/nixpkgs/stable/#fun-substitute-subst-var-by)
10 flag, names are encoded as `@name@` in the provided file at the provided path.
11
12 Any unmatched variable names in the file at the provided path will cause a build failure.
13
14 By default, any remaining text that matches `@[A-Za-z_][0-9A-Za-z_'-]@` in the output after replacement
15 has occurred will cause a build failure. Variables can be excluded from this check by passing "null" for them.
16
17 # Inputs
18
19 `src` ([Store Path](https://nixos.org/manual/nix/latest/store/store-path.html#store-path) String)
20 : The file in which to replace variables.
21
22 `replacements` (AttrsOf String)
23 : Each entry in this set corresponds to a `--subst-var-by` entry in [`substitute`](https://nixos.org/manual/nixpkgs/stable/#fun-substitute) or
24 null to keep it unchanged.
25
26 # Example
27
28 ```nix
29 { replaceVars }:
30
31 replaceVars ./greeting.txt { world = "hello"; }
32 ```
33
34 See `../../test/replace-vars/default.nix` for tests of this function.
35*/
36src: replacements: replaceVarsWith { inherit src replacements; }