From e6f67aa910f78ecf75f3a47a0794497148c60c2b Mon Sep 17 00:00:00 2001
From: lassulus <lassulus@lassul.us>
Date: Tue, 7 Jun 2022 15:43:30 +0200
Subject: l drbd module: init

---
 lass/3modules/default.nix |   1 +
 lass/3modules/drbd.nix    | 118 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 119 insertions(+)
 create mode 100644 lass/3modules/drbd.nix

diff --git a/lass/3modules/default.nix b/lass/3modules/default.nix
index 570bb45b..3a0b1306 100644
--- a/lass/3modules/default.nix
+++ b/lass/3modules/default.nix
@@ -2,6 +2,7 @@ _:
 {
   imports = [
     ./dnsmasq.nix
+    ./drbd.nix
     ./folderPerms.nix
     ./hosts.nix
     ./klem.nix
diff --git a/lass/3modules/drbd.nix b/lass/3modules/drbd.nix
new file mode 100644
index 00000000..816e58f0
--- /dev/null
+++ b/lass/3modules/drbd.nix
@@ -0,0 +1,118 @@
+{ config, lib, pkgs, ... }: let
+  cfg = config.lass.drbd;
+  slib = import <stockholm/lib>;
+in {
+  options = {
+    lass.drbd = lib.mkOption {
+      default = {};
+      type = lib.types.attrsOf (lib.types.submodule ({ config, ... }: {
+        options = {
+          name = lib.mkOption {
+            type = lib.types.str;
+            default = config._module.args.name;
+          };
+          blockMinor = lib.mkOption {
+            type = lib.types.int;
+            default = lib.mod (slib.genid config.name) 16000; # TODO get max_id fron drbd
+          };
+          port = lib.mkOption {
+            type = lib.types.int;
+            default = 20000 + config.blockMinor;
+          };
+          peers = lib.mkOption {
+            type = lib.types.listOf slib.types.host;
+          };
+          disk = lib.mkOption {
+            type = lib.types.str;
+            default = "/dev/loop${toString config.blockMinor}";
+          };
+          drbdConfig = lib.mkOption {
+            type = lib.types.path;
+            internal = true;
+            default = pkgs.writeText "drbd-${config.name}.conf" ''
+              resource ${config.name} {
+                net {
+                  protocol a;
+                  ping-int 10;
+                }
+                device minor ${toString config.blockMinor};
+                disk ${config.disk};
+                meta-disk internal;
+                ${slib.indent (lib.concatStrings (lib.imap1 (i: peer: /* shell */ ''
+                  on ${peer.name} {
+                    address ${peer.nets.retiolum.ip4.addr}:${toString config.port};
+                    node-id ${toString i};
+                  }
+                '') config.peers))}
+                connection-mesh {
+                  hosts ${lib.concatMapStringsSep " " (peer: peer.name) config.peers};
+                }
+              }
+            '';
+          };
+        };
+      }));
+    };
+  };
+  config = lib.mkIf (cfg != {}) {
+    boot.extraModulePackages = [
+      (pkgs.linuxPackages.callPackage ../5pkgs/drbd9/default.nix {})
+    ];
+    boot.extraModprobeConfig = ''
+      options drbd usermode_helper=/run/current-system/sw/bin/drbdadm
+    '';
+    services.udev.packages = [ pkgs.drbd ];
+    boot.kernelModules = [ "drbd" ];
+
+    environment.systemPackages = [ pkgs.drbd ];
+
+
+    networking.firewall.allowedTCPPorts = map (device: device.port) (lib.attrValues cfg);
+    systemd.services = lib.mapAttrs' (_: device:
+      lib.nameValuePair "drbd-${device.name}" {
+        after = [ "systemd-udev.settle.service" "network.target" ];
+        wants = [ "systemd-udev.settle.service" ];
+        wantedBy = [ "multi-user.target" ];
+        serviceConfig = {
+          RemainAfterExit = true;
+          ExecStart = pkgs.writers.writeDash "start-drbd-${device.name}" ''
+            set -efux
+            mkdir -p /var/lib/sync-containers2
+            ${lib.optionalString (device.disk == "/dev/loop${toString device.blockMinor}") ''
+              if ! test -e /var/lib/sync-containers2/${device.name}.disk; then
+                truncate -s 10G /var/lib/sync-containers2/${device.name}.disk
+              fi
+              if ! ${pkgs.util-linux}/bin/losetup /dev/loop${toString device.blockMinor}; then
+                ${pkgs.util-linux}/bin/losetup /dev/loop${toString device.blockMinor} /var/lib/sync-containers2/${device.name}.disk
+              fi
+            ''}
+            if ! ${pkgs.drbd}/bin/drbdadm adjust ${device.name}; then
+              ${pkgs.drbd}/bin/drbdadm down ${device.name}
+              ${pkgs.drbd}/bin/drbdadm create-md ${device.name}
+              ${pkgs.drbd}/bin/drbdadm up ${device.name}
+            fi
+          '';
+          ExecStop = pkgs.writers.writeDash "stop-drbd-${device.name}" ''
+            set -efux
+            ${pkgs.drbd}/bin/drbdadm -c ${device.drbdConfig} down ${device.name}
+            ${lib.optionalString (device.disk == "/dev/loop${toString device.blockMinor}") ''
+              ${pkgs.util-linux}/bin/losetup -d /dev/loop${toString device.blockMinor}
+            ''}
+          '';
+        };
+      }
+    ) cfg;
+
+
+    environment.etc."drbd.conf".text = ''
+      global {
+        usage-count yes;
+      }
+
+      ${lib.concatMapStrings (device: /* shell */ ''
+        include ${device.drbdConfig};
+      '') (lib.attrValues cfg)}
+    '';
+  };
+}
+
-- 
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