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https://github.com/fzakaria/nix-auto-follow
A script to achieve automatically following all flake inputs for Nix
https://github.com/fzakaria/nix-auto-follow
nix nixos nixpkgs
Last synced: 6 days ago
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A script to achieve automatically following all flake inputs for Nix
- Host: GitHub
- URL: https://github.com/fzakaria/nix-auto-follow
- Owner: fzakaria
- License: mit
- Created: 2024-08-01T05:13:49.000Z (2 months ago)
- Default Branch: main
- Last Pushed: 2024-08-21T04:23:15.000Z (about 1 month ago)
- Last Synced: 2024-09-24T00:32:33.920Z (9 days ago)
- Topics: nix, nixos, nixpkgs
- Language: Python
- Homepage:
- Size: 37.1 KB
- Stars: 50
- Watchers: 3
- Forks: 3
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
README
# nix-auto-follow
[](https://builtwithnix.org)
```console
❯ nix run github:fzakaria/nix-auto-follow -- --help
usage: auto-follow [-h] [--in-place] [filename]
Update nix flake.lock file to autofollow.
positional arguments:
filename The path to the flake.lock file.
options:
-h, --help show this help message and exit
--in-place, -i Write the output back to the same file.
```
> A (python) script to achieve automatically following all flake inputs for Nix.
If you have used [Nix](https://nixos.org) flakes, you likely encountered something like this 🤢
```nix
std.url = "github:divnix/std";
std.inputs.devshell.follows = "devshell";
std.inputs.nixago.follows = "nixago";
std.inputs.nixpkgs.follows = "nixpkgs";
hive.url = "github:divnix/hive";
hive.inputs.colmena.follows = "colmena";
hive.inputs.disko.follows = "disko";
hive.inputs.nixos-generators.follows = "nixos-generators";
hive.inputs.nixpkgs.follows = "nixpkgs";
```
Why is this **follows** necessary?
It's in fact not _necessary_ but it makes the Nix evaluation simpler.
Rather than using the exact Nix flake commit your dependency desires, we are _overriding it_, with one we have likely already declared.
This has the effect of making our graph smaller, which is faster to evaluate and likely build.
> Note: Although it's _faster_ it's _less correct_ since we are deviating from what the authors of the flake desired.
Writing all those `follows` can get real teadious, and it's tough to even know you did it all... surely there has to be a better way!
There is with this script 🥳
Simply run the script which will modify your `flake.lock` file. Commit the change and voila!
```console
❯ auto-follow -i
```
## Validation
The `auto-follow` tool includes a _check mode_ ; so that you can validate you are correctly following everything.
```console
❯ auto-follow -c
All ok!
```
This will fail (exit code 1) if not everything can be deduped.
```console
❯ auto-follow -c
Node a has input nixpkgs pointing to nixpkgs_2 which is not the same as b's nixpkgs which is nixpkgs_3 in the lockfile.
Please add 'nixpkgs.url = "github:nixos/nixpkgs/nixos-23.11"' or 'nixpkgs.url = "github:nixos/nixpkgs/nixos-23.05'
```
Note: This can still happen _even after modifying your lock file_.
The reason for this is that if the top-level Nix expression (your application _flake.nix_) does not include all possible flakes, then
there is no way for us to know which of the two choices we should consolidate to. The tool prints a friendly message showing some of the possible
options to select amongst.
## Development
Running the development shell should drop you into a shell with all the required dependencies and the editable installation already done.
```console
❯ nix develop
```