From 20b5cd1498fcd0e03e7c92dd40e78cdb8bc35b8b Mon Sep 17 00:00:00 2001
From: Nathan Perry <np@nathanperry.dev>
Date: Mon, 28 Nov 2022 10:58:46 -0500
Subject: nix: write nixos module

---
 flake.nix | 219 +++++++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 190 insertions(+), 29 deletions(-)

diff --git a/flake.nix b/flake.nix
index 476498b..6fa6db4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -25,7 +25,36 @@
     nixpkgs,
     flake-utils,
     ...
-  } @ inputs: (flake-utils.lib.eachDefaultSystem (system:
+  } @ inputs: let
+    buildToolchain = pkgs: pkgs.rust-bin.nightly."2022-11-20".minimal;
+    deps = pkgs: with pkgs; [
+      openssl
+      pkgconfig
+      libopus
+      postgresql
+    ];
+
+    mkPkg = pkgs: let
+      buildToolchain = buildToolchain pkgs;
+
+      naersk = pkgs.callPackage inputs.naersk {
+        cargo = buildToolchain;
+        rustc = buildToolchain;
+      };
+
+      inherit (pkgs) lib;
+
+    in naersk.buildPackage {
+      pname = "thulani";
+      version = self.rev or "dirty";
+
+      src = lib.cleanSource ./.;
+
+      nativeBuildInputs = deps pkgs;
+      remapPathPrefix = true;
+    };
+
+  in (flake-utils.lib.eachDefaultSystem (system:
     let
       pkgs = import nixpkgs {
         inherit system;
@@ -35,9 +64,7 @@
         ];
       };
 
-      buildToolchain = pkgs.rust-bin.nightly."2022-11-20".minimal;
-
-      devToolchain = buildToolchain.override {
+      devToolchain = (buildToolchain pkgs).override {
         extensions = [
           "rust-src"
           "rust-analyzer"
@@ -47,35 +74,13 @@
         ];
       };
 
-      naersk = pkgs.callPackage inputs.naersk {
-        cargo = buildToolchain;
-        rustc = buildToolchain;
-      };
-
-      deps = with pkgs; [
-        openssl
-        pkgconfig
-        libopus
-        postgresql
-      ];
-
-      inherit (pkgs) lib;
-
-      pkg = naersk.buildPackage {
-        pname = "thulani";
-        version = self.rev or "dirty";
-
-        src = lib.cleanSource ./.;
-
-        nativeBuildInputs = deps;
-        remapPathPrefix = true;
-      };
+      pkg = mkPkg pkgs;
 
     in {
       devShells.default = pkgs.mkShell {
         buildInputs = (with pkgs; [
           devToolchain
-        ]) ++ deps;
+        ]) ++ (deps pkgs);
 
         RUST_SRC_PATH = "${devToolchain}/lib/rustlib/src/rust";
       };
@@ -85,6 +90,162 @@
         type = "app";
         program = "${pkg}/bin/thulani";
       };
-    })
+
+    }) // {
+      overlays.default = final: prev: let
+        withRust = (import inputs.rust-overlay) final prev;
+      in {
+        thulani = mkPkg withRust;
+      };
+
+      nixosModules.default = { pkgs, lib, config, ... }: let
+        cfg = config.services.thulani;
+      in {
+        options.services.thulani = with lib; with lib.types; {
+          enable = mkEnableOption "thulani";
+
+          package = mkOption {
+            description = "thulani derivation to use";
+            type = package;
+            default = pkgs.thulani;
+          };
+
+          environment = mkOption {
+            description = "literal environment to include";
+            type = attrsOf str;
+            default = {};
+          };
+
+          envFiles = mkOption {
+            description = "environment files to include";
+            type = listOf path;
+            default = [];
+          };
+
+          user = mkOption {
+            description = "user to run service as";
+            type = str;
+            default = "thulani";
+          };
+
+          group = mkOption {
+            description = "group to run service as";
+            type = str;
+            default = "thulani";
+          };
+
+          postgres = mkOption {
+            description = "local postgres server with automatic setup";
+
+            type = sumodule {
+              enable = mkEnableOption "postgres";
+
+              db = mkOption {
+                description = "db name";
+                type = str;
+                default = "memes";
+              };
+            };
+          };
+        };
+
+        config = lib.mkIf cfg.enable {
+          systemd.services.thulani = {
+            description = "thulani bot";
+
+            wantedBy = [
+              "multi-user.target"
+            ];
+
+            bindsTo = [
+              "network-online.target"
+            ];
+
+            after = [
+              "network-online.target"
+            ];
+
+            preStart = lib.mkIf (cfg.postgres.enable) (let
+              invokePsql = "${pkgs.sudo}/bin/sudo -u ${config.services.postgresql.superUser} -- ${config.services.postgresql.package}/bin/psql";
+
+            in ''
+              ${invokePsql} <<EOF
+              DO $$
+              BEGIN
+              CREATE ROLE ${cfg.user};
+              EXCEPTION WHEN duplicate_object THEN RAISE NOTICE '%, skipping', SQLERRM USING ERRCODE = SQLSTATE;
+              END
+              $$;
+
+              SELECT 'CREATE DATABASE ${cfg.postgres.db}'
+              WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '${cfg.postgres.db}')\gexec
+              EOF
+
+              echo 'CREATE EXTENSION IF NOT EXISTS pgcrypto' | ${invokePsql} ${cfg.postgres.db}
+            '');
+
+            inherit (cfg) environment;
+
+            unitConfig = {
+              StartLimitBurst = 3;
+              StartLimitIntervalSec = "1m";
+            };
+
+            serviceConfig = {
+              Type = "exec";
+              ExecStart = "${cfg.package}/bin/thulani";
+
+              EnvironmentFile = cfg.environmentFiles;
+
+              DynamicUser = true;
+              User = cfg.user;
+              Group = cfg.group;
+
+              Restart = "always";
+              RestartSec = "10s";
+
+              TimeoutStopSec = "10s";
+
+              MemoryHigh = "200M";
+              MemoryMax = "300M";
+
+              ProtectSystem = "strict";
+              ProtectProc = "noaccess";
+              ProtectHome = true;
+              ProtectHostname = true;
+              ProtectClock = true;
+              ProtectKernelTunables = true;
+              ProtectKernelModules = true;
+              ProtectKernelLogs = true;
+              ProtectControlGroups = true;
+
+              PrivateDevices = true;
+              PrivateUsers = true;
+              PrivateMounts = true;
+
+              RestrictNamespaces = true;
+              RestrictRealtime = true;
+              RestrictSUIDSGID = true;
+
+              MemoryDenyWriteExecute = true;
+              LockPersonality = true;
+              NoNewPrivileges = true;
+              KeyringMode = "private";
+
+              SystemCallFilter = "@system-service";
+              SystemCallErrorNumber = "EPERM";
+            };
+          };
+
+          services.postgresql = lib.mkIf cfg.postgres.enable {
+            enable = true;
+
+            authentication = ''
+              local ${cfg.postgres.db} ${cfg.user} ident
+            '';
+          };
+        };
+      };
+    }
   );
 }
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