fuuko: Add aria2

machines/fuuko/configuration.nix

@@ -9,6 +9,7 @@
     ./services/media.nix
     ./services/prometheus.nix
     ./services/scan.nix
+    ./services/torrent.nix
   ];
 
   sbruder = {

machines/fuuko/services/prometheus.nix

@@ -66,6 +66,14 @@ in
           "vueko.vpn.sbruder.de:9100"
         ];
       }
+      {
+        job_name = "aria2";
+        static_configs = mkStaticTarget "127.0.0.1:9578";
+        relabel_configs = lib.singleton {
+          target_label = "instance";
+          replacement = "torrent.sbruder.de";
+        };
+      }
       {
         job_name = "fritzbox";
         static_configs = mkStaticTarget "127.0.0.1:9133";
@@ -113,6 +121,11 @@ in
                 for = "10m";
                 description = "Thinkpad T440’s ACPI temperature is broken. Its reported temperature is 48 °C for the last 10 minutes. That doesn’t seem right. Try suspending";
               }
+              {
+                name = "TorrentNoPeers";
+                expr = "sum by (instance) (aria2_torrent_peers) == 0";
+                description = "Aria2 instance {{ $labels.instance }} has no peers. There might be a network connectivity problem";
+              }
             ];
           };
         })

machines/fuuko/services/torrent.nix

@@ -0,0 +1,209 @@
+{ config, lib, pkgs, ... }:
+let
+  homeDir = "/var/lib/aria2";
+  downloadDir = "/data/torrent";
+  sessionFile = "${homeDir}/session";
+
+  settings = {
+    # locations
+    dir = downloadDir;
+
+    # logging
+    show-console-readout = false;
+    summary-interval = 0;
+
+    # rpc
+    enable-rpc = true;
+
+    # permanent queue
+    bt-load-saved-metadata = true;
+    bt-save-metadata = true;
+    force-save = true;
+    input-file = sessionFile;
+    save-session = sessionFile;
+    save-session-interval = 900; # automatic saving
+
+    # network
+    async-dns-server = "193.138.218.74"; # aria2 does not respect netns resolv.conf
+    dht-listen-port = 54971;
+    listen-port = 54931;
+    interface = "wg-aria";
+
+    # limits
+    max-concurrent-downloads = 65536;
+    max-overall-download-limit = "6M";
+    max-overall-upload-limit = "4M";
+    seed-ratio = 0; # do not stop seeding after reaching ratio
+  };
+
+  toString' = value:
+    if lib.isBool value
+    then (if value then "true" else "false")
+    else (toString value);
+
+  configFile = pkgs.writeText "aria2.conf" (lib.concatStringsSep
+    "\n"
+    (lib.mapAttrsToList
+      (k: v: "${k}=${toString' v}")
+      settings));
+
+  # Without this patch, the download and upload lengths are wrong after pausing
+  # and unpausing. I don’t patch this globally (in the overlay), since aria2 is
+  # in the user environment and would have to be rebuilt on slow machines.
+  aria2 = pkgs.aria2.overrideAttrs (o: o // {
+    patches = [
+      (pkgs.fetchpatch {
+        url = "https://github.com/aria2/aria2/commit/6ebdddb9f159e87923736f25900897b3602305f9.diff";
+        sha256 = "1j5mnafiv92xnzghh03hfdvpn9647vfdcipamnvi8hnzk3ak4mj7";
+      })
+    ];
+  });
+
+  mkProxyService = socket: port: {
+    wantedBy = [ "multi-user.target" ];
+    after = [ "wireguard-wg-aria.service" ];
+    partOf = [ "wireguard-wg-aria.service" ];
+
+    serviceConfig = {
+      PrivateNetwork = true;
+      NetworkNamespacePath = "/run/netns/aria2";
+
+      Restart = "always";
+      ExecStart = "${pkgs.socat}/bin/socat UNIX-LISTEN:${socket},fork,reuseaddr,mode=660 TCP:127.0.0.1:${toString port}";
+      User = "aria2";
+      Group = "nginx";
+
+      # systemd-analyze --no-pager security aria2-rpc-proxy.service
+      CapabilityBoundingSet = null;
+      PrivateDevices = true;
+      PrivateTmp = true;
+      PrivateUsers = true;
+      ProtectHome = true;
+      RestrictNamespaces = true;
+      SystemCallFilter = "@system-service";
+    };
+  };
+in
+{
+  users.users.aria2 = {
+    group = "aria2";
+    uid = config.ids.uids.aria2;
+    home = homeDir;
+  };
+
+  users.groups.aria2.gid = config.ids.gids.aria2;
+
+  systemd.tmpfiles.rules = [
+    "d '${downloadDir}' 0775 aria2 users - -"
+    "d '${homeDir}' 0771 aria2 aria2 - -"
+  ];
+
+  krops.secrets.wg-aria-private-key = { };
+
+  networking.wireguard.interfaces.wg-aria = {
+    interfaceNamespace = "aria2";
+    preSetup = "ip netns add aria2 && ip -n aria2 link set lo up";
+    postShutdown = "ip netns del aria2";
+
+    privateKeyFile = config.krops.secrets.wg-aria-private-key.path;
+  } // (import ../secrets/aria2-wireguard.nix); # potentially sensitive data
+
+  systemd.services.aria2 = {
+    description = "aria2 Service";
+    after = [ "wireguard-wg-aria.service" ];
+    requires = [ "wireguard-wg-aria.service" ];
+    wantedBy = [ "multi-user.target" ];
+    preStart = ''
+      if [[ ! -e "${sessionFile}" ]]; then
+        touch "${sessionFile}"
+      fi
+    '';
+
+    serviceConfig = {
+      PrivateNetwork = true;
+      NetworkNamespacePath = "/run/netns/aria2";
+
+      Restart = "always";
+      ExecStart = "${aria2}/bin/aria2c --conf-path=${configFile}";
+      ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+      User = "aria2";
+      Group = "aria2";
+
+      # systemd-analyze --no-pager security aria2.service
+      CapabilityBoundingSet = null;
+      PrivateDevices = true;
+      PrivateTmp = true;
+      PrivateUsers = true;
+      ProtectHome = true;
+      RestrictNamespaces = true;
+      SystemCallFilter = "@system-service";
+    };
+  };
+
+  systemd.services.aria2-rpc-proxy = mkProxyService "${homeDir}/rpc.sock" 6800;
+
+  services.aria2_exporter = {
+    enable = true;
+    listenAddress = "localhost:9578";
+  };
+
+  systemd.services.aria2_exporter = {
+    after = [ "wireguard-wg-aria.service" ];
+    partOf = [ "wireguard-wg-aria.service" ];
+
+    serviceConfig = {
+      PrivateNetwork = true;
+      NetworkNamespacePath = "/run/netns/aria2";
+    };
+  };
+
+  systemd.services.aria2_exporter-proxy = mkProxyService "${homeDir}/metrics.sock" 9578;
+
+  services.nginx.virtualHosts."torrent.sbruder.de" = {
+    enableACME = true;
+    forceSSL = true;
+
+    # treated as state
+    basicAuthFile = "${homeDir}/htpasswd";
+
+    locations = {
+      "/" = {
+        root = toString (import
+          (pkgs.fetchzip {
+            url = "https://git.sbruder.de/simon/AriaNg/archive/51c53f298091a6a6b6077febc2bc9370acb47271.tar.gz";
+            sha256 = "0f8j86l3fw71q1m00radlv2bg33l9jad0razyalvspzam3p3bsk1";
+          })
+          { inherit pkgs; });
+      };
+      "/jsonrpc" = {
+        proxyPass = "http://unix:${homeDir}/rpc.sock";
+        proxyWebsockets = true;
+      };
+      "/download/" = {
+        alias = "${downloadDir}/";
+        extraConfig = ''
+          autoindex on;
+        '';
+      };
+      "=/metrics" = {
+        proxyPass = "http://unix:${homeDir}/metrics.sock";
+      };
+    };
+  };
+
+  services.nginx.virtualHosts."aria2-metrics" = {
+    listen = lib.singleton {
+      addr = "127.0.0.1";
+      port = 9578;
+    };
+
+    locations."=/metrics" = {
+      proxyPass = "http://unix:${homeDir}/metrics.sock";
+    };
+  };
+
+  environment.systemPackages = with pkgs; [
+    aria2
+    mktorrent
+  ];
+}