feat(monorepo-gerrit): Configure outbound emails for reviews r/923

Configures Gerrit send emails from tvlbot@tazj.in for outgoing review
notifications. Emails are always plain-text and can contain diffs (up
to a maximum size of 256KiB).

The configuration options for this are documented at:

https://gerrit-review.googlesource.com/Documentation/config-gerrit.html#sendemail

Note: The password for this user is stored on the host, in a file that
is not part of version-control and is only readable by the 'git' user.

We should probably figure out a way to do secrets management ...

Change-Id: I2f99b34b1a774c28d814b0aba1f1b78fd512854e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/92
Reviewed-by: riking <rikingcoding@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/ops/nixos/modules/monorepo-gerrit.nix b/ops/nixos/modules/monorepo-gerrit.nix
index b51a6d8b294c..174c59948e29 100644
--- a/ops/nixos/modules/monorepo-gerrit.nix
+++ b/ops/nixos/modules/monorepo-gerrit.nix
@@ -45,6 +45,25 @@ in {
         # TODO(tazjin): Assuming this is what we'll be doing ...
         groupMemberPattern = "(&(objectClass=group)(member=\${dn}))";
       };
+
+      # Email sending (emails are relayed via the tazj.in domain's
+      # GSuite currently).
+      #
+      # Note that sendemail.smtpPass is stored in
+      # $site_path/etc/secure.config and is *not* controlled by Nix.
+      #
+      # Receiving email is not currently supported.
+      sendemail = {
+        enable = true;
+        html = false;
+        connectTimeout = "30sec";
+        from = "TVL Code Review <tvlbot@tazj.in>";
+        includeDiff = true;
+        smtpEncryption = "tls";
+        smtpServer = "smtp.gmail.com";
+        smtpServerPort = 587;
+        smtpUser = "tvlbot@tazj.in";
+      };
     };
   };