From 6ab6724e4c49ae7df5afda042a536e7a13dddf25 Mon Sep 17 00:00:00 2001
From: Vincent Ambo <mail@tazj.in>
Date: Sun, 3 Jul 2022 14:34:29 +0300
Subject: feat(ops/modules): add module for receiving a depot replica

This module sets up a user with an SSH key and permissions to receive
a (pushed) replica of depot from Gerrit.

This still needs appropriate configuration in Gerrit's replication
plugin on the other end.

This module has been enabled for sanduny. For now it does not (yet)
configure git serving.

Change-Id: I0fb6f7e696609e71008308e855bdf305dcbcd4f7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5913
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: sterni <sternenseemann@systemli.org>
---
 ops/machines/sanduny/default.nix |  4 ++++
 ops/modules/depot-replica.nix    | 45 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 ops/modules/depot-replica.nix

diff --git a/ops/machines/sanduny/default.nix b/ops/machines/sanduny/default.nix
index 4767f6a7bd65..23d77e947453 100644
--- a/ops/machines/sanduny/default.nix
+++ b/ops/machines/sanduny/default.nix
@@ -14,6 +14,7 @@ let
 in
 {
   imports = [
+    (mod "depot-replica.nix")
     (mod "journaldriver.nix")
     (mod "known-hosts.nix")
     (mod "tvl-cache.nix")
@@ -76,6 +77,9 @@ in
     preserveGenerations = "90d";
   };
 
+  # Allow Gerrit to replicate depot to /var/lib/depot
+  services.depot.replica.enable = true;
+
   time.timeZone = "UTC";
 
   # GRUB does not actually need to be installed on disk; Bitfolk have
diff --git a/ops/modules/depot-replica.nix b/ops/modules/depot-replica.nix
new file mode 100644
index 000000000000..f5f02a18a9fc
--- /dev/null
+++ b/ops/modules/depot-replica.nix
@@ -0,0 +1,45 @@
+# Configuration for receiving a depot replica from Gerrit's
+# replication plugin.
+#
+# This only prepares the user and folder for receiving the replica,
+# but Gerrit configuration still needs to be modified in addition.
+{ config, depot, lib, pkgs, ... }:
+
+let
+  cfg = config.services.depot.replica;
+in
+{
+  options.services.depot.replica = with lib; {
+    enable = mkEnableOption "Receive depot git replica from Gerrit";
+
+    key = mkOption {
+      description = "Public key to use for replication";
+      type = types.str;
+      default = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFFab9O1xaQ1TCyn+CxmXHexdlLzURREG+UR3Qdi3BvH";
+    };
+
+    path = mkOption {
+      description = "Replication destination path (will be created)";
+      type = types.str;
+      default = "/var/lib/depot";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    users.groups.depot = { };
+
+    users.users.depot = {
+      group = "depot";
+      isSystemUser = true;
+      createHome = true;
+      home = cfg.path;
+      homeMode = "750"; # group can read depot
+      openssh.authorizedKeys.keys = lib.singleton cfg.key;
+      shell = pkgs.bashInteractive; # gerrit needs to run shell commands
+    };
+
+    environment.systemPackages = [
+      pkgs.git
+    ];
+  };
+}
-- 
cgit 1.4.1