From 6774129851ce47a9ab62cf8d909895e52dc02adb Mon Sep 17 00:00:00 2001
From: Raito Bezarius <masterancpp@gmail.com>
Date: Wed, 1 Jan 2025 02:58:19 +0100
Subject: [PATCH] feat(hosts/bagel-box): enable secrets-agent on this machine

And we use it for RabbitMQ mTLS authentication.

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>
---
 hosts/bagel-box/default.nix |  9 ++++++
 services/ofborg/default.nix | 55 ++++++++++++++++++++++++++-----------
 2 files changed, 48 insertions(+), 16 deletions(-)

diff --git a/hosts/bagel-box/default.nix b/hosts/bagel-box/default.nix
index a7abf5f..1743493 100644
--- a/hosts/bagel-box/default.nix
+++ b/hosts/bagel-box/default.nix
@@ -52,6 +52,15 @@
       # FIXME: plug into our prometheus stack.
       stats.enable = true;
     };
+
+    secrets-agent = {
+      enable = true;
+      methods.token = {
+        enable = true;
+        tenancy = "floral";
+        identifier = "bagel-box";
+      };
+    };
   };
 
   bagel.sysadmin.enable = true;
diff --git a/services/ofborg/default.nix b/services/ofborg/default.nix
index fff6b20..7d4fc8d 100644
--- a/services/ofborg/default.nix
+++ b/services/ofborg/default.nix
@@ -21,8 +21,7 @@ let
       RuntimeDirectory = "ofborg";
       WorkingDirectory = "/var/lib/ofborg";
       LoadCredential =
-        optional (hasAttr "rabbitmq-password" config.age.secrets) "rabbitmq-password:${config.age.secrets.rabbitmq-password.path}"
-        ++ optional (hasAttr "gerrit-event-listener-ssh-key" config.age.secrets) "gerrit-ssh-key:${config.age.secrets.gerrit-event-listener-ssh-key.path}";
+        optional (hasAttr "gerrit-event-listener-ssh-key" config.age.secrets) "gerrit-ssh-key:${config.age.secrets.gerrit-event-listener-ssh-key.path}";
       Environment = [
         "XDG_STATE_HOME=/run/ofborg"
       ];
@@ -45,6 +44,20 @@ in {
     settings = mkOption {
       type = generators.type;
     };
+
+    pki = {
+      cacertFile = mkOption {
+        type = types.path;
+        description = "CA certificate file for mTLS in OfBorg";
+        default = config.bagel.pki.cacertFile;
+      };
+      rootPath = mkOption {
+        type = types.str;
+        description = "Root mountpoint for PKI issuing in the Vault cluster";
+        example = "floral_systems/v1/infra/v1";
+        default = config.bagel.pki.rootPath;
+      };
+    };
   };
 
   config = mkMerge [
@@ -97,27 +110,37 @@ in {
       };
     }
     (mkIf cfg.rabbitmq.enable {
-      age.secrets.rabbitmq-password.file = ../../secrets/floral/rabbitmq-password.age;
-      services.nginx.enable = true;
+      systemd.services.rabbitmq.vault = {
+        # TODO: Reloading implies rabbitmqctl eval -n [target-node@hostname] 'ssl:clear_pem_cache().'
+        template = ''
+          {{ with pkiCert "${cfg.pki.rootPath}/issue/rabbitmq-server" "common_name=${amqpHost}" }}
+          {{ scratch.MapSet "secrets" "server.pem" .Data.Cert }}
+          {{ scratch.MapSet "secrets" "server.key" .Data.Key }}
+          {{ end }}
+          {{ scratch.Get "secrets" | explodeMap | toJSON }}
+        '';
+        secrets = {
+          "server.pem" = {};
+          "server.key" = {};
+        };
+      };
       services.rabbitmq = {
         enable = true;
         configItems = {
           "listeners.tcp" = "none";
           "listeners.ssl.default" = builtins.toString amqpPort;
-          "ssl_options.certfile" = "${config.security.acme.certs.${amqpHost}.directory}/cert.pem";
-          "ssl_options.keyfile" = "${config.security.acme.certs.${amqpHost}.directory}/key.pem";
+          # TODO(upstream): this should accept path as well…
+          "ssl_options.cacertfile" = "${cfg.pki.cacertFile}";
+          "ssl_options.certfile" = "/run/credentials/rabbitmq.service/server.pem";
+          "ssl_options.keyfile" = "/run/credentials/rabbitmq.service/server.key";
+          "ssl_options.verify" = "verify_peer";
+          # TODO(upstream): …
+          "ssl_options.fail_if_no_peer_cert" = "true";
+          # TLS authentication via X.509
+          "auth_mechanisms.1" = "EXTERNAL";
+          "ssl_cert_login_from" = "common_name";
         };
       };
-
-      security.acme.certs.${amqpHost} = {
-        webroot = "/var/lib/acme/.challenges";
-        group = "rabbitmq";
-      };
-      services.nginx.virtualHosts.${amqpHost}.locations."/.well-known/acme-challenge".root =
-        "/var/lib/acme/.challenges";
-      systemd.services.rabbitmq.requires = ["acme-finished-${amqpHost}.target"];
-
-      networking.firewall.allowedTCPPorts = [ amqpPort ];
     })
     (mkIf cfg.pastebin.enable {
       systemd.services.ofborg-pastebin = mkOfborgWorker "pastebin-worker" { };