From 10f8246ac44223aaa8cfd2955d47fc8ea17d51b8 Mon Sep 17 00:00:00 2001
From: Tim Van Baak <tim.vanbaak@gmail.com>
Date: Tue, 13 Dec 2022 20:03:28 -0800
Subject: [PATCH] Add nixos module

---
 flake.nix  |   1 +
 module.nix | 154 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 155 insertions(+)
 create mode 100644 module.nix

diff --git a/flake.nix b/flake.nix
index 0565086..3eb8d36 100644
--- a/flake.nix
+++ b/flake.nix
@@ -32,5 +32,6 @@
         projectDir = ./.;
       }).dependencyEnv;
     };
+    nixosModules.default = import ./module.nix self;
   };
 }
diff --git a/module.nix b/module.nix
new file mode 100644
index 0000000..58a2196
--- /dev/null
+++ b/module.nix
@@ -0,0 +1,154 @@
+flake: { config, lib, pkgs, ... }:
+
+let
+  inherit (lib) mkIf mkOption types;
+
+  cfg = config.services.inquisitor;
+in
+{
+  options = {
+    services.inquisitor = {
+      enable = mkOption {
+        type = types.bool;
+        default = true;
+        description = "Enable the Inquisitor aggregator.";
+      };
+
+      listen.addr = mkOption {
+        type = types.str;
+        default = "0.0.0.0";
+        description = "Listen address passed to nginx.";
+      };
+
+      listen.port = mkOption {
+        type = types.port;
+        default = 80;
+        description = "Listen port passed to nginx.";
+      };
+    };
+  };
+
+  config =
+  let
+    # Get the inquisitor package from the flake.
+    inquisitor = flake.packages.${pkgs.system}.default;
+
+    # Define the inquisitor state directory.
+    stateDir = "/var/lib/inquisitor";
+
+    # Define an scp helper for item callbacks to use.
+    scp-helper = pkgs.writeShellScriptBin "scp-helper" ''
+      ${pkgs.openssh}/bin/scp -i ${stateDir}/.ssh/inquisitor.key -oStrictHostKeyChecking=no "$@"
+    '';
+
+    # Define the inquisitor service user.
+    svcUser = {
+      name = "inquisitor";
+      group = "inquisitor";
+      description = "Inquisitor service user";
+      isSystemUser = true;
+      shell = pkgs.bashInteractive;
+      packages = [ inquisitor pkgs.cron ];
+    };
+
+    # Create a config file pointing to the state directory.
+    inqConfig = pkgs.writeTextFile {
+      name = "inquisitor.conf";
+      text = ''
+        DataPath = ${stateDir}/data/
+        SourcePath = ${stateDir}/sources/
+        CachePath = ${stateDir}/cache/
+        Verbose = false
+        LogFile = ${stateDir}/inquisitor.log
+      '';
+    };
+
+    # Create a setup script to ensure the service directory state.
+    inqSetup = pkgs.writeShellScript "inquisitor-setup.sh" ''
+      # Ensure the required directories exist.
+      ${pkgs.coreutils}/bin/mkdir -p ${stateDir}/data/inquisitor/
+      ${pkgs.coreutils}/bin/mkdir -p ${stateDir}/sources/
+      ${pkgs.coreutils}/bin/mkdir -p ${stateDir}/cache/
+      if [ ! -f ${stateDir}/data/inquisitor/state ]; then
+        ${pkgs.coreutils}/bin/echo "{}" > ${stateDir}/data/inquisitor/state
+      fi
+
+      # Ensure the service owns the folders.
+      ${pkgs.coreutils}/bin/chown -R ${svcUser.name} ${stateDir}
+
+      # Ensure the scp helper is present
+      if [ -f ${stateDir}/scp-helper ]; then
+        ${pkgs.coreutils}/bin/rm ${stateDir}/scp-helper
+      fi
+      ln -s -t ${stateDir}/scp-helper ${scp-helper}/bin/scp-helper
+    '';
+
+    # Create a run script for the service.
+    inqRun = pkgs.writeShellScript "inquisitor-run.sh" ''
+      cd ${stateDir}
+      ${inquisitor}/bin/gunicorn \
+        --bind=localhost:24133 \
+        --workers=4 \
+        --timeout 120 \
+        --log-level debug \
+        "inquisitor.app:wsgi()"
+    '';
+
+    # Create a wrapper to execute the cli as the service user.
+    # (needed to avoid creating files in the state dir the service can't read)
+    inqWrapper = pkgs.writeShellScriptBin "inq" ''
+      sudo --user=${svcUser.name} ${inquisitor}/bin/inquisitor "$@"
+    '';
+  in mkIf cfg.enable
+  {
+    users.users.inquisitor = svcUser;
+    users.groups.inquisitor = {};
+
+    # Link the config in /etc to avoid envvar shenanigans
+    environment.etc."inquisitor.conf".source = inqConfig;
+
+    # Give all users the wrapper program.
+    environment.systemPackages = [ inqWrapper ];
+    # Allow the sudo in the cli wrapper without password.
+    security.sudo.extraRules = [{
+      commands = [{
+        command = "${inquisitor}/bin/inquisitor";
+        options = [ "NOPASSWD" ];
+      }];
+      runAs = svcUser.name;
+      groups = [ "users" ];
+    }];
+
+    # Run the setup script on activation.
+    system.activationScripts.inquisitorSetup = "${inqSetup}";
+
+    # Set up the inquisitor service.
+    systemd.services.inquisitor = {
+      description = "Inquisitor server";
+      script = "${inqRun}";
+      serviceConfig = {
+        User = svcUser.name;
+        Type = "simple";
+      };
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network.target" ];
+      enable = true;
+    };
+
+    # Set up the nginx reverse proxy to the server.
+    services.nginx.enable = true;
+    services.nginx.virtualHosts.inquisitorHost = {
+      listen = [ cfg.listen ];
+      locations."/".extraConfig = ''
+        access_log /var/log/nginx/access.inquisitor.log;
+        proxy_buffering off;
+        proxy_pass http://localhost:24133/;
+      '';
+    };
+    networking.firewall.allowedTCPPorts = [ cfg.listen.port ];
+
+    # Enable cron so the service can use it to schedule fetches.
+    services.cron.enable = true;
+  };
+}
+