[nix] searxng recipe for installation via nix

- flake & compatibility
- searxng package & overlay for installation via Nix package manager
- development shell with make & python with dependencies for local
  execution of built artifact

.gitignore

@@ -15,3 +15,4 @@ dist/
 local/
 gh-pages/
 *.egg-info/
+/result

default.nix

@@ -0,0 +1,9 @@
+(import (
+  let
+    lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+  in fetchTarball {
+    url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+    sha256 = lock.nodes.flake-compat.locked.narHash; }
+) {
+  src =  ./.;
+}).defaultNix

flake.lock

@@ -0,0 +1,126 @@
+{
+  "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1627913399,
+        "narHash": "sha256-hY8g6H2KFL8ownSiFeMOjwPC8P0ueXpCVEbxgda3pko=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "12c64ca55c1014cdc1b16ed5a804aa8576601ff2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1629481132,
+        "narHash": "sha256-JHgasjPR0/J1J3DRm4KxM4zTyAj4IOJY8vIl75v/kPI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "997f7efcb746a9c140ce1f13c72263189225f482",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_2": {
+      "locked": {
+        "lastModified": 1601282935,
+        "narHash": "sha256-WQAFV6sGGQxrRs3a+/Yj9xUYvhTpukQJIcMbIi7LCJ4=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "588973065fce51f4763287f0fda87a174d78bf48",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "mach-nix-src": {
+      "inputs": {
+        "flake-utils": "flake-utils_2",
+        "nixpkgs": "nixpkgs",
+        "pypi-deps-db": "pypi-deps-db"
+      },
+      "locked": {
+        "lastModified": 1629464241,
+        "narHash": "sha256-DLAVO2fyj5VxDf/7FoBsXZTQcz1/deJ9EFRqO9BD0tI=",
+        "owner": "DavHau",
+        "repo": "mach-nix",
+        "rev": "d223656fc0eff33f4da77d69db19752edc9a5ba5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "DavHau",
+        "repo": "mach-nix",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1622797669,
+        "narHash": "sha256-xIyWeoYExzF0KNaKcqfxEX58fN4JTIQxTJWbsAujllc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "1ca6b0a0cc38dbba0441202535c92841dd39d1ae",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-unstable",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1631135948,
+        "narHash": "sha256-Awt0CTDsECS4Z1Iqn4bkH9CAfPcECOniOXazomMGUnA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "95bfcf1e2475b780dd7dbba503fc06ac8e1faa79",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "pypi-deps-db": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1622970040,
+        "narHash": "sha256-u//RFnae/XMIhoy83G2uH2Qu/1LiUhVCdwwY1xj4Ufs=",
+        "owner": "DavHau",
+        "repo": "pypi-deps-db",
+        "rev": "be6591698c67a86a69c81fef72167e38d038a9fc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "DavHau",
+        "repo": "pypi-deps-db",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "flake-utils": "flake-utils",
+        "mach-nix-src": "mach-nix-src",
+        "nixpkgs": "nixpkgs_2"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,99 @@
+{
+  description = "SearXNG";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs";
+    mach-nix-src.url = "github:DavHau/mach-nix";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  inputs.flake-compat = {
+    url = "github:edolstra/flake-compat";
+    flake = false;
+  };
+
+  outputs = { self, nixpkgs, flake-utils, mach-nix-src, ... }:
+    let
+      # TODO : for some reason `nix flake show` results in error:
+      # ```error: a 'aarch64-darwin' with features {} is required to build '/nix/store/s79ixgs3xy250x1b9vyy90g7dzd6bsh4-conda-channels.json.drv',
+      #   but I am a 'x86_64-linux' with features {benchmark, big-parallel, kvm, nixos-test}```
+      # Some internal part of mach-nix attempts to build derivation into target system and cross-build fails
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      #
+      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
+      forAllSystems = f:
+        nixpkgs.lib.genAttrs supportedSystems (system: f system);
+
+      python = "python38";
+      pypiDataRev = "18250538b9eeb9484c4e3bdf135bc1f3a2ccd949";
+      pypiDataSha256 = "01hdjy5rpcjm92fyp8n6lci773rgbsa81h2n08r49zjhk9michrb";
+      requirements = builtins.readFile ./requirements.txt;
+
+      nixpkgsFor = forAllSystems (
+        system:
+          import nixpkgs {
+            inherit system;
+            overlays = [ self.overlay ];
+          }
+      );
+    in
+      {
+
+        overlay = final: prev:
+          let
+            mach-nix = import mach-nix-src {
+              pkgs = prev;
+              inherit python pypiDataRev pypiDataSha256;
+            };
+          in
+            {
+              searxng = (
+                mach-nix.buildPythonPackage {
+                  inherit requirements;
+                  pname = "SearXNG";
+                  version = "1.0";
+                  src = ./.;
+                }
+              );
+              dev-python =
+                  mach-nix.mkPython {
+                    inherit python;
+                    requirements = requirements;
+                  };
+            };
+        packages = forAllSystems (
+          system:
+            {
+              inherit (nixpkgsFor.${system}) searxng;
+            }
+        );
+
+        # The default package for 'nix build'. This makes sense if the
+        # flake provides only one package or there is a clear "main"
+        # package.
+        # Returns Searx with plugin enabled
+        defaultPackage = forAllSystems (system: self.packages.${system}.searxng);
+
+        # To use as `nix develop`
+        # will provide shell with
+        # - make utility for `make run` and `make test`
+        # - python with dependencies, to run searx built with nix
+        # - env var pointing to default repository searx config
+        devShell = forAllSystems (
+          system: nixpkgsFor.${system}.mkShell
+            rec {
+              buildInputs = with nixpkgsFor.${system}; [
+                dev-python
+                gnumake
+              ];
+              settingsFile = builtins.readFile ./searx/settings.yml;
+              SEARX_SETTINGS_PATH = "${settingsFile}";
+            }
+        );
+
+        nixosModules.searxng = { pkgs, ... }:
+          {
+            nixpkgs.overlays = [ self.overlay ];
+          };
+      };
+}

shell.nix

@@ -0,0 +1,9 @@
+(import (
+  let
+    lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+  in fetchTarball {
+    url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+    sha256 = lock.nodes.flake-compat.locked.narHash; }
+) {
+  src =  ./.;
+}).shellNix