From 81e12969eb48566bbae28d4864abaeee8dcb5c80 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Tue, 24 Aug 2021 22:30:44 +0200
Subject: [PATCH] modules: services: nginx: overhaul modularity

This should be all that's needed for almost all my services.
---
 machines/porthos/services.nix |   3 +
 modules/services/nginx.nix    | 182 ++++++++++++++++++++++++++++++++--
 2 files changed, 175 insertions(+), 10 deletions(-)

diff --git a/machines/porthos/services.nix b/machines/porthos/services.nix
index ac33819..cc8672d 100644
--- a/machines/porthos/services.nix
+++ b/machines/porthos/services.nix
@@ -90,6 +90,9 @@ in
       enable = true;
       password = my.secrets.nextcloud.password;
     };
+    nginx = {
+      enable = true; # FIXME: remove this when done migrating
+    };
     # The whole *arr software suite
     pirate.enable = true;
     # Podcast automatic downloader
diff --git a/modules/services/nginx.nix b/modules/services/nginx.nix
index ac70c48..2a64c65 100644
--- a/modules/services/nginx.nix
+++ b/modules/services/nginx.nix
@@ -1,12 +1,147 @@
-# Configuration shamelessly stolen from [1]
-#
-# [1]: https://github.com/delroth/infra.delroth.net/blob/master/common/nginx.nix
+# A simple abstraction layer for almost all of my services' needs
 { config, lib, pkgs, ... }:
+let
+  cfg = config.my.services.nginx;
 
+  virtualHostOption = with lib; types.submodule {
+    options = {
+      subdomain = mkOption {
+        type = types.str;
+        example = "dev";
+        description = ''
+          Which subdomain, under config.networking.domain, to use
+          for this virtual host.
+        '';
+      };
+
+      port = mkOption {
+        type = with types; nullOr port;
+        default = null;
+        example = 8080;
+        description = ''
+          Which port to proxy to, through 127.0.0.1, for this virtual host.
+          This option is incompatible with `root`.
+        '';
+      };
+
+      root = mkOption {
+        type = with types; nullOr path;
+        default = null;
+        example = "/var/www/blog";
+        description = ''
+          The root folder for this virtual host.  This option is incompatible
+          with `port`.
+        '';
+      };
+
+      extraConfig = mkOption {
+        type = types.attrs; # FIXME: forward type of virtualHosts
+        example = litteralExample ''
+          {
+            locations."/socket" = {
+              proxyPass = "http://127.0.0.1:8096/";
+              proxyWebsockets = true;
+            };
+          }
+        '';
+        default = { };
+        description = ''
+          Any extra configuration that should be applied to this virtual host.
+        '';
+      };
+    };
+  };
+in
 {
-  # Whenever something defines an nginx vhost, ensure that nginx defaults are
-  # properly set.
-  config = lib.mkIf ((builtins.attrNames config.services.nginx.virtualHosts) != [ ]) {
+  options.my.services.nginx = with lib; {
+    enable =
+      mkEnableOption "Nginx, activates when `virtualHosts` is not empty" // {
+        default = builtins.length cfg.virtualHosts != 0;
+      };
+
+    monitoring = {
+      enable = my.mkDisableOption "monitoring through grafana and prometheus";
+    };
+
+    virtualHosts = mkOption {
+      type = types.listOf virtualHostOption;
+      default = [ ];
+      example = litteralExample ''
+        [
+          {
+            subdomain = "gitea";
+            port = 8080;
+          }
+          {
+            subdomain = "dev";
+            root = "/var/www/dev";
+          }
+          {
+            subdomain = "jellyfin";
+            port = 8096;
+            extraConfig = {
+              locations."/socket" = {
+                proxyPass = "http://127.0.0.1:8096/";
+                proxyWebsockets = true;
+              };
+            };
+          }
+        ]
+      '';
+      description = ''
+        List of virtual hosts to set-up using default settings.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [ ]
+      ++ (lib.flip builtins.map cfg.virtualHosts ({ subdomain, ... } @ args:
+      let
+        conflicts = [ "port" "root" ];
+        optionsNotNull = builtins.map (v: args.${v} != null) conflicts;
+        optionsSet = lib.filter lib.id optionsNotNull;
+      in
+      {
+        assertion = builtins.length optionsSet == 1;
+        message = ''
+          Subdomain '${subdomain}' must have exactly one of ${
+            lib.concatStringsSep ", " (builtins.map (v: "'${v}'") conflicts)
+          } configured.
+        '';
+      }))
+      ++ (
+      let
+        ports = lib.my.mapFilter
+          (v: v != null)
+          ({ port, ... }: port)
+          cfg.virtualHosts;
+        portCounts = lib.my.countValues ports;
+        nonUniquesCounts = lib.filterAttrs (_: v: v != 1) portCounts;
+        nonUniques = builtins.attrNames nonUniquesCounts;
+        mkAssertion = port: {
+          assertion = false;
+          message = "Port ${port} cannot appear in multiple virtual hosts.";
+        };
+      in
+      map mkAssertion nonUniques
+    ) ++ (
+      let
+        subs = map ({ subdomain, ... }: subdomain) cfg.virtualHosts;
+        subsCounts = lib.my.countValues subs;
+        nonUniquesCounts = lib.filterAttrs (_: v: v != 1) subsCounts;
+        nonUniques = builtins.attrNames nonUniquesCounts;
+        mkAssertion = v: {
+          assertion = false;
+          message = ''
+            Subdomain '${v}' cannot appear in multiple virtual hosts.
+          '';
+        };
+      in
+      map mkAssertion nonUniques
+    )
+    ;
+
     services.nginx = {
       enable = true;
       statusPage = true; # For monitoring scraping.
@@ -15,6 +150,33 @@
       recommendedOptimisation = true;
       recommendedTlsSettings = true;
       recommendedProxySettings = true;
+
+      virtualHosts =
+        let
+          domain = config.networking.domain;
+          mkVHost = ({ subdomain, ... } @ args: lib.nameValuePair
+            "${subdomain}.${domain}"
+            (builtins.foldl' lib.recursiveUpdate { } [
+              # Base configuration
+              {
+                forceSSL = true;
+                useACMEHost = domain;
+              }
+              # Proxy to port
+              (lib.optionalAttrs (args.port != null) {
+                locations."/".proxyPass =
+                  "http://127.0.0.1:${toString args.port}";
+              })
+              # Serve filesystem content
+              (lib.optionalAttrs (args.root != null) {
+                inherit (args) root;
+              })
+              # VHost specific configuration
+              args.extraConfig
+            ])
+          );
+        in
+        lib.my.genAttrs' cfg.virtualHosts mkVHost;
     };
 
     networking.firewall.allowedTCPPorts = [ 80 443 ];
@@ -22,10 +184,10 @@
     # Nginx needs to be able to read the certificates
     users.users.nginx.extraGroups = [ "acme" ];
 
-    # Use DNS wildcard certificate
     security.acme = {
       email = "bruno.acme@belanyi.fr";
       acceptTerms = true;
+      # Use DNS wildcard certificate
       certs =
         let
           domain = config.networking.domain;
@@ -40,8 +202,8 @@
           };
         };
     };
-    # Setup monitoring
-    services.grafana.provision.dashboards = [
+
+    services.grafana.provision.dashboards = lib.mkIf cfg.monitoring.enable [
       {
         name = "NGINX";
         options.path = pkgs.nur.repos.alarsyo.grafanaDashboards.nginx;
@@ -49,7 +211,7 @@
       }
     ];
 
-    services.prometheus = {
+    services.prometheus = lib.mkIf cfg.monitoring.enable {
       exporters.nginx = {
         enable = true;
         listenAddress = "127.0.0.1";