Added a script that list least important nixos generations

.gitignore

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+.direnv
+.ipynb_checkpoints
+notebooks/
+.envrc

README.md

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+# Nixos Utils
+
+Collection of tools to help with nixos

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1764242076,
+        "narHash": "sha256-sKoIWfnijJ0+9e4wRvIgm/HgE27bzwQxcEmo2J/gNpI=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "2fad6eac6077f03fe109c4d4eb171cf96791faa4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "A very basic flake";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+        python-env = pkgs.python3.withPackages
+          (ps: with ps; [ jupyter requests pandas matplotlib click ]);
+      in {
+        devShells.default = pkgs.mkShell { buildInputs = [ python-env ]; };
+      });
+}

src/main.py

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+import click
+
+import subprocess
+from pathlib import Path
+from io import BytesIO
+import pandas as pd
+import json
+
+def get_generations():
+    cmd = ['nixos-rebuild', 'list-generations']
+    process = subprocess.Popen(cmd,  stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    stdout, stderr = process.communicate()
+    process.wait()
+    return BytesIO(stdout)
+
+
+def get_generations_as_df():
+    generations = get_generations()
+    df = pd.read_csv(generations,  sep=r'\s\s+', engine='python')
+    df['Build-date'] = pd.to_datetime(df['Build-date'], format='%Y-%m-%d %H:%M:%S')
+    df['Time-To-Next-Build'] = -df['Build-date'].diff(periods=1)
+    df['nix-store'] = df['Generation'].map(lambda x: str((Path('/nix/var/nix/profiles/') / f'system-{x}-link').readlink()))
+    return df
+
+
+def _get_generations_by_time_to_next_build(df):
+    return df.sort_values('Time-To-Next-Build').to_dict(orient='records')
+
+def _get_old_duplicate_generation_ids(df):
+    return df[df.duplicated('nix-store', keep='last')]
+
+
+def get_generations_by_importance():
+    df = get_generations_as_df()
+    old_duplicates = _get_old_duplicate_generation_ids(df)
+    yield from old_duplicates.to_dict(orient='records')
+    df = df.drop(old_duplicates.index)
+
+    yield from _get_generations_by_time_to_next_build(df)
+
+
+@click.group()
+def cli():
+    pass
+
+@cli.command()
+@click.option('--max', default=-1)
+def list_generations(max):
+    """
+    List all nix generation by the lest important first.  The least
+    important generations are old duplicated generations.  Once all
+    of these are passed, an unimportant generation is a generation
+    that has been rapidly over wridden"""
+    generations = list(get_generations_by_importance())
+    max = len(generations) if max == 0 else max
+    for generation in generations[:max]:
+        generation['Build-date'] = str(generation['Build-date'])
+        if generation.get('Time-To-Next-Build'):
+            generation['Time-To-Next-Build'] = generation['Time-To-Next-Build'].total_seconds()
+        print(json.dumps(generation))
+
+
+if __name__ == '__main__':
+    cli()
+8179