diff --git a/configs/all-configurations.nix b/configs/all-configurations.nix
index a6566344b..bd2f936c1 100644
--- a/configs/all-configurations.nix
+++ b/configs/all-configurations.nix
@@ -2,7 +2,9 @@
   # LiberaForms is intentionally disabled.
   # Refer to <https://github.com/ngi-nix/ngipkgs/issues/40>.
   #liberaforms-container = import ./liberaforms/container.nix;
-
+  flarum = {
+    imports = [./flarum];
+  };
   pretalx-postgresql = {
     imports = [
       ./pretalx/pretalx.nix
diff --git a/configs/flarum/default.nix b/configs/flarum/default.nix
new file mode 100644
index 000000000..399d6ac29
--- /dev/null
+++ b/configs/flarum/default.nix
@@ -0,0 +1,14 @@
+{
+  boot.isContainer = true;
+  networking.hostName = "test-flarum";
+
+  # Allow nginx through the firewall
+  networking.firewall.allowedTCPPorts = [80];
+
+  services.nginx.enable = true;
+  nixpkgs.hostPlatform = "x86_64-linux";
+  services.flarum = {
+    enable = true;
+    domain = "10.233.2.2";
+  };
+}
diff --git a/flake.lock b/flake.lock
index d22f9a36b..6c2c29a9d 100644
--- a/flake.lock
+++ b/flake.lock
@@ -42,15 +42,16 @@
         "flake-parts": "flake-parts"
       },
       "locked": {
-        "lastModified": 1693994164,
-        "narHash": "sha256-BtVCeCp5TInZ40bQtOAgT/0ghKWY+fW5EORFelFtcP4=",
+        "lastModified": 1691252882,
+        "narHash": "sha256-kCiFl72gV/OzDPCrw2CeHM6VEtVGFj57gaF8ZKD9LWI=",
         "owner": "loophp",
         "repo": "nix-php-composer-builder",
-        "rev": "600bc67c1adce95675d6c3487ba61ae5fab4dc25",
+        "rev": "0caf5a60753397cfa959a74fc9ea0562556573c1",
         "type": "github"
       },
       "original": {
         "owner": "loophp",
+        "ref": "0caf5a60753397cfa959a74fc9ea0562556573c1",
         "repo": "nix-php-composer-builder",
         "type": "github"
       }
diff --git a/flake.nix b/flake.nix
index 6cfdbfccc..261e5d00a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,7 +2,7 @@
   description = "NgiPkgs";
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
-  inputs.nix-php-composer-builder.url = "github:loophp/nix-php-composer-builder";
+  inputs.nix-php-composer-builder.url = "github:loophp/nix-php-composer-builder?ref=0caf5a60753397cfa959a74fc9ea0562556573c1";
   inputs.flake-utils.url = "github:numtide/flake-utils";
   # Set default system to `x86_64-linux`,
   # as we currently only support Linux.
@@ -25,14 +25,10 @@
   }:
     with builtins; let
       importPackages = pkgs:
-        import ./all-packages.nix {
-          inherit (pkgs) newScope;
-        };
+        import ./all-packages.nix {inherit (pkgs) newScope;};
 
       importNixpkgs = system: overlays:
-        import nixpkgs {
-          inherit system overlays;
-        };
+        import nixpkgs {inherit system overlays;};
 
       importNixosConfigurations = import ./configs/all-configurations.nix;
 
@@ -47,15 +43,13 @@
 
       # Compute outputs that are invariant in the system architecture.
       allSystemsOutputs = system: let
-        pkgs = importNixpkgs system [
-          nix-php-composer-builder.overlays.default
-        ];
+        pkgs =
+          importNixpkgs system [nix-php-composer-builder.overlays.default];
         treefmtEval = loadTreefmt pkgs;
       in {
         packages = importPackages pkgs;
         formatter = treefmtEval.config.build.wrapper;
       };
-    in
       # We merge three attribute sets to construct all outputs:
       #  1. Outputs that are invariant in the system architecture
       #     via `flake-utils.lib.eachDefaultSystem`.
@@ -64,6 +58,7 @@
       #  3. Outputs that are not tied to any system at all.
       #
       # 1.
+    in
       (flake-utils.lib.eachDefaultSystem allSystemsOutputs)
       #
       # 2.
@@ -90,29 +85,28 @@
 
         # `nixosTests` is a non-standard name for a flake output.
         # See <https://github.com/ngi-nix/ngipkgs/issues/28>.
-        nixosTests.${linuxSystem} = mapAttrs (_: pkgs.nixosTest) (import ./tests/all-tests.nix {
-          modules = extendedModules;
-          configurations = importNixosConfigurations;
-        });
+        nixosTests.${linuxSystem} =
+          mapAttrs (_: pkgs.nixosTest)
+          (import ./tests/all-tests.nix {
+            modules = extendedModules;
+            configurations = importNixosConfigurations;
+          });
       })
       #
       # 3.
       // {
-        nixosConfigurations =
-          mapAttrs (
-            _: config:
-              nixpkgs.lib.nixosSystem {
-                modules = [config] ++ nixpkgs.lib.attrValues extendedModules;
-              }
-          )
-          importNixosConfigurations;
+        nixosConfigurations = mapAttrs (_: config:
+          nixpkgs.lib.nixosSystem {
+            modules = [config] ++ nixpkgs.lib.attrValues extendedModules;
+          })
+        importNixosConfigurations;
 
         nixosModules =
           (import ./modules/all-modules.nix)
           // {
             # The default module adds the default overlay on top of nixpkgs.
             # This is so that `ngipkgs` can be used alongside `nixpkgs` in a configuration.
-            default.nixpkgs.overlays = [self.overlays.default];
+            default.nixpkgs.overlays = [self.overlays.default nix-php-composer-builder.overlays.default];
           };
 
         # Overlays a package set (e.g. nixpkgs) with the packages defined in this flake.
diff --git a/modules/all-modules.nix b/modules/all-modules.nix
index 7847be27b..add3da330 100644
--- a/modules/all-modules.nix
+++ b/modules/all-modules.nix
@@ -3,4 +3,5 @@
   # Refer to <https://github.com/ngi-nix/ngipkgs/issues/40>.
   #liberaforms = import ./liberaforms.nix;
   pretalx = import ./pretalx.nix;
+  flarum = import ./flarum.nix;
 }
diff --git a/modules/flarum.nix b/modules/flarum.nix
new file mode 100644
index 000000000..253144711
--- /dev/null
+++ b/modules/flarum.nix
@@ -0,0 +1,217 @@
+{
+  config,
+  lib,
+  pkgs,
+  self,
+  utils,
+  ...
+}:
+with builtins;
+with lib; let
+  cfg = config.services.flarum;
+  opt = options.services.flarum;
+
+  flarumInstallConfig = pkgs.writeText "config.json" (builtins.toJSON {
+    debug = false;
+    offline = false;
+
+    baseUrl = cfg.baseUrl;
+    databaseConfiguration = cfg.database;
+    adminUser = {
+      username = cfg.adminUser;
+      password = cfg.initialAdminPassword;
+      email = cfg.adminEmail;
+    };
+    settings = {forum_title = cfg.forumTitle;};
+  });
+in {
+  options = {
+    services.flarum = with types; {
+      enable = mkEnableOption "Flarum discussion platform";
+
+      package = mkPackageOption pkgs "flarum" {};
+
+      forumTitle = mkOption {
+        type = types.str;
+        default = "A Flarum Forum on NixOS";
+        description = "Title of the forum.";
+      };
+
+      domain = mkOption {
+        type = types.str;
+        default = "localhost";
+        example = "forum.example.com";
+        description = "Domain to serve on.";
+      };
+
+      baseUrl = mkOption {
+        type = types.str;
+        default = "https://${cfg.domain}";
+        example = "https://forum.example.com";
+        description = "Change `domain` instead.";
+      };
+
+      adminUser = mkOption {
+        type = types.str;
+        default = "flarum";
+        description = "Username for first web application administrator";
+      };
+
+      adminEmail = mkOption {
+        type = types.str;
+        default = "admin@example.com";
+        description = "Email for first web application administrator";
+      };
+
+      initialAdminPassword = mkOption {
+        type = types.str;
+        default = "flarum";
+        description = "Initial password for the adminUser";
+      };
+
+      user = mkOption {
+        type = types.str;
+        default = "flarum";
+        description = "System user to run Flarum";
+      };
+
+      group = mkOption {
+        type = types.str;
+        default = "flarum";
+        description = "System group to run Flarum";
+      };
+
+      stateDir = mkOption {
+        type = types.path;
+        default = "/var/lib/flarum";
+        description = "Home directory for writable storage";
+      };
+
+      database = mkOption rec {
+        type = with types; attrsOf (oneOf [str bool int]);
+        description = "MySQL database parameters";
+        default = {
+          # the database driver; i.e. MySQL; MariaDB...
+          driver = "mysql";
+          # the host of the connection; localhost in most cases unless using an external service
+          host = "localhost";
+          # the name of the database in the instance
+          database = "flarum";
+          # database username
+          username = "flarum";
+          # database password
+          password = "";
+          # the prefix for the tables; useful if you are sharing the same database with another service
+          prefix = "";
+          # the port of the connection; defaults to 3306 with MySQL
+          port = 3306;
+          strict = false;
+        };
+      };
+
+      createDatabaseLocally = mkOption {
+        type = types.bool;
+        default = true;
+        description = "Create the database and database user locally, and run installation.";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    users.users.${cfg.user} = {
+      isSystemUser = true;
+      home = cfg.stateDir;
+      createHome = true;
+      group = cfg.group;
+    };
+    users.groups.${cfg.group} = {};
+
+    services.phpfpm.pools.flarum = {
+      user = cfg.user;
+      settings = {
+        "listen.owner" = config.services.nginx.user;
+        "listen.group" = config.services.nginx.group;
+        "listen.mode" = "0600";
+        "pm" = mkDefault "dynamic";
+        "pm.max_children" = mkDefault 10;
+        "pm.max_requests" = mkDefault 500;
+        "pm.start_servers" = mkDefault 2;
+        "pm.min_spare_servers" = mkDefault 1;
+        "pm.max_spare_servers" = mkDefault 3;
+      };
+      phpOptions = ''
+        error_log = syslog
+        log_errors = on
+      '';
+    };
+
+    services.nginx = {
+      enable = true;
+      virtualHosts."${cfg.domain}" = {
+        root = "${cfg.stateDir}/public";
+        locations."~ \.php$".extraConfig = ''
+          fastcgi_pass unix:${config.services.phpfpm.pools.flarum.socket};
+          fastcgi_index site.php;
+        '';
+        extraConfig = ''
+          index index.php
+          include ${cfg.package}/build/.nginx.conf;
+        '';
+      };
+    };
+
+    services.mysql = mkIf cfg.enable {
+      enable = true;
+      package = pkgs.mysql;
+      ensureDatabases = [cfg.database.database];
+      ensureUsers = [
+        {
+          name = cfg.database.username;
+          ensurePermissions = {
+            "${cfg.database.database}.*" = "ALL PRIVILEGES";
+          };
+        }
+      ];
+    };
+
+    assertions = [
+      {
+        assertion = !cfg.createDatabaseLocally || cfg.database.driver == "mysql";
+        message = "Flarum can only be automatically installed in MySQL/MariaDB.";
+      }
+    ];
+
+    systemd.services.flarum-install = {
+      description = "Flarum installation";
+      requiredBy = ["phpfpm-flarum.service"];
+      before = ["phpfpm-flarum.service"];
+      requires = ["mysql.service"];
+      after = ["mysql.service"];
+      serviceConfig = {
+        Type = "oneshot";
+        User = cfg.user;
+        Group = cfg.group;
+      };
+      path = [config.services.phpfpm.phpPackage];
+      script =
+        ''
+          mkdir -p ${cfg.stateDir}/{extensions,public/assets/avatars}
+          mkdir -p ${cfg.stateDir}/storage/{formatter,sessions,views}
+          cd ${cfg.stateDir}
+          cp -f ${cfg.package}/build/{extend.php,site.php,flarum} .
+          ln -sf ${cfg.package}/build/vendor .
+          ln -sf ${cfg.package}/build/public/index.php public/
+          chmod a+x . public
+          chmod +x site.php extend.php flarum
+        ''
+        + lib.optionalString
+        (cfg.createDatabaseLocally && cfg.database.driver == "mysql") ''
+          if [ ! -f config.php ]; then
+             php flarum install --file=${flarumInstallConfig}
+          fi
+          php flarum migrate
+          # php flarum cache:clear
+        '';
+    };
+  };
+}