feat(servers): setup cluster resource options

devices/cluster/default.nix

@@ -9,7 +9,7 @@ in {
     ../../modules/tailscale.nix
 
     ./modules/corosync.nix
-    ./modules/pacemaker.nix
+    ./modules/pacemaker
   ];
 
   vars = {

devices/cluster/modules/pacemaker.nix

@@ -1,19 +0,0 @@
-{nixpkgs-pacemaker, ...}: let
-  pacemakerPath = "services/cluster/pacemaker/default.nix";
-in {
-  # FIXME: https://github.com/NixOS/nixpkgs/pull/208298
-  nixpkgs.overlays = [
-    (final: prev: {
-      inherit
-        (nixpkgs-pacemaker.legacyPackages.x86_64-linux)
-        pacemaker
-        ocf-resource-agents
-        ;
-    })
-  ];
-
-  disabledModules = [pacemakerPath];
-  imports = ["${nixpkgs-pacemaker}/nixos/modules/${pacemakerPath}"];
-
-  services.pacemaker.enable = true;
-}

devices/cluster/modules/pacemaker/default.nix

@@ -0,0 +1,9 @@
+{...}: {
+  imports = [./options.nix];
+
+  services.pacemaker = {
+    enable = true;
+
+    resources = {};
+  };
+}

devices/cluster/modules/pacemaker/options.nix

@@ -0,0 +1,203 @@
+{
+  config,
+  lib,
+  nixpkgs-pacemaker,
+  pkgs,
+  ...
+}: let
+  inherit
+    (lib)
+    attrNames
+    attrValues
+    concatMapStringsSep
+    elemAt
+    filterAttrs
+    mkIf
+    mkOption
+    types
+    ;
+  inherit (builtins) toFile map listToAttrs;
+
+  pacemakerPath = "services/cluster/pacemaker/default.nix";
+  cfg = config.services.pacemaker;
+in {
+  disabledModules = [pacemakerPath];
+  imports = ["${nixpkgs-pacemaker}/nixos/modules/${pacemakerPath}"];
+
+  options.services.pacemaker = {
+    networkInterface = mkOption {
+      default = "eno1";
+      type = types.str;
+    };
+
+    resources = mkOption {
+      default = {};
+      type = with types;
+        attrsOf (submodule ({name, ...}: {
+          options = {
+            enable = mkOption {
+              default = true;
+              type = types.bool;
+            };
+
+            systemdName = mkOption {
+              default = name;
+              type = types.str;
+            };
+
+            virtualIp = mkOption {
+              default = null;
+              type = types.nullOr types.str;
+            };
+
+            dependsOn = mkOption {
+              default = [];
+              # TODO: implement dependsOn
+              type = types.listOf types.str;
+            };
+
+            # TODO: Add extraResources, extraConstraints ...
+          };
+        }));
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services = let
+      mkVirtIp = res: ''
+        <primitive class="ocf" id="${res.systemdName}vip" provider="heartbeat" type="IPaddr2">
+            <instance_attributes id="${res.systemdName}vip-attrs">
+                <nvpair
+                    id="${res.systemdName}vip-attrs-cidr_netmask"
+                    name="cidr_netmask"
+                    value="24"
+                />
+                <nvpair
+                    id="${res.systemdName}vip-attrs-ip"
+                    name="ip"
+                    value="${res.virtualIp}"
+                />
+                <nvpair
+                    id="${res.systemdName}vip-attrs-nic"
+                    name="nic"
+                    value="${cfg.networkInterface}"
+                />
+            </instance_attributes>
+            <operations>
+                <op
+                    id="${res.systemdName}vip-monitor-interval-30s"
+                    interval="30s"
+                    name="monitor"
+                />
+                <op
+                    id="${res.systemdName}vip-start-interval-0s"
+                    interval="0s"
+                    name="start"
+                    timeout="20s"
+                />
+                <op
+                    id="${res.systemdName}vip-stop-interval-0s"
+                    interval="0s"
+                    name="stop"
+                    timeout="20s"
+                />
+            </operations>
+        </primitive>
+      '';
+
+      mkSystemdResource = res: ''
+        <primitive id="${res.systemdName}" class="systemd" type="${res.systemdName}">
+            <operations>
+                <op id="stop-${res.systemdName}" name="stop" interval="0" timeout="10s"/>
+                <op id="start-${res.systemdName}" name="start" interval="0" timeout="10s"/>
+                <op id="monitor-${res.systemdName}" name="monitor" interval="10s" timeout="20s"/>
+            </operations>
+        </primitive>
+      '';
+
+      mkConstraint = first: res: ''
+        <rsc_order
+            id="order-${res.systemdName}"
+            first="${first}"
+            then="${res.systemdName}"
+            kind="Mandatory"
+        />
+        <rsc_colocation
+            id="colocate-${res.systemdName}"
+            rsc="${first}"
+            with-rsc="${res.systemdName}"
+            score="INFINITY"
+        />
+      '';
+
+      mkVipConstraint = res:
+        mkConstraint
+        (res.systemdName + "vip")
+        res;
+
+      # If we're updating resources we have to kill constraints to add new resources
+      constraintsEmpty = toFile "constraints.xml" ''
+        <constraints>
+        </constraints>
+      '';
+
+      resEnabled = filterAttrs (n: v: v.enable) cfg.resources;
+
+      resWithIp = filterAttrs (n: v: ! isNull v.virtualIp) resEnabled;
+
+      resources = toFile "resources.xml" ''
+        <resources>
+            ${concatMapStringsSep "\n" mkVirtIp (attrValues resWithIp)}
+            ${concatMapStringsSep "\n" mkSystemdResource (attrValues resEnabled)}
+        </resources>
+      '';
+
+      constraints = toFile "constraints.xml" ''
+        <constraints>
+            ${concatMapStringsSep "\n" mkVipConstraint (attrValues resWithIp)}
+        </constraints>
+      '';
+
+      host1 = (elemAt config.services.corosync.nodelist 0).name;
+    in
+      {
+        "pacemaker-setup" = {
+          after = ["corosync.service" "pacemaker.service"];
+
+          path = with pkgs; [pacemaker];
+
+          script = ''
+            # The config needs to be installed from one node only
+            if [ "$(uname -n)" = ${host1} ]; then
+                # TODO: setup stonith / fencing
+                crm_attribute --type crm_config --name stonith-enabled --update false
+                crm_attribute --type crm_config --name no-quorum-policy --delete
+
+                # Install config
+                cibadmin --replace --scope constraints --xml-file ${constraintsEmpty}
+                cibadmin --replace --scope resources --xml-file ${resources}
+                cibadmin --replace --scope constraints --xml-file ${constraints}
+            fi
+          '';
+        };
+      }
+      # Force all systemd units handled by pacemaker to not start automatically
+      // listToAttrs (map (x: {
+        name = x;
+        value = {
+          wantedBy = lib.mkForce [];
+        };
+      }) (attrNames cfg.resources));
+
+    # FIXME: https://github.com/NixOS/nixpkgs/pull/208298
+    nixpkgs.overlays = [
+      (final: prev: {
+        inherit
+          (nixpkgs-pacemaker.legacyPackages.x86_64-linux)
+          pacemaker
+          ocf-resource-agents
+          ;
+      })
+    ];
+  };
+}