From 5bde7e23581dbcc588561bb0bf579ec43f6240ba Mon Sep 17 00:00:00 2001
From: Yureka <yuka@yuka.dev>
Date: Sat, 20 Jul 2024 15:13:44 +0200
Subject: [PATCH] use dedicated store partition for hydra builds

---
 services/baremetal-builder/default.nix | 12 ++++++++++++
 services/hydra/default.nix             |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/services/baremetal-builder/default.nix b/services/baremetal-builder/default.nix
index 5ae0820..f3dfa70 100644
--- a/services/baremetal-builder/default.nix
+++ b/services/baremetal-builder/default.nix
@@ -57,6 +57,11 @@ in
       fsType = "xfs";
     };
 
+    fileSystems."/mnt" = {
+      device = "/dev/disk/by-label/hydra";
+      fsType = "xfs";
+    };
+
     fileSystems."/boot" = {
       device = "/dev/disk/by-label/BOOT";
       fsType = "vfat";
@@ -135,6 +140,13 @@ in
       MaxStartups = "500:30:1000";
     };
 
+    systemd.services.hydra-gc = {
+      description = "Nix Garbage Collector";
+      script = "exec ${config.nix.package.out}/bin/nix-store --gc --store /mnt";
+      serviceConfig.Type = "oneshot";
+      startAt = "hourly";
+    };
+    systemd.timers.hydra-gc.timerConfig.Persistent = true;
 
     bagel.sysadmin.enable = true;
 
diff --git a/services/hydra/default.nix b/services/hydra/default.nix
index dec68b0..7fcfeae 100644
--- a/services/hydra/default.nix
+++ b/services/hydra/default.nix
@@ -14,7 +14,7 @@ let
   # XXX: to support Nix's dumb public host key syntax (base64'd), this outputs
   # a string with shell-style command interpolations: $(...).
   mkBaremetalBuilder = { parallelBuilds, publicHostKey, host, speedFactor ? 1, user ? "builder", supportedSystems ? [ "i686-linux" "x86_64-linux" ], supportedFeatures ? [ "big-parallel" "kvm" "nixos-test" ] }:
-  "ssh://${user}@${host} ${lib.concatStringsSep "," supportedSystems} ${config.age.secrets.hydra-ssh-key-priv.path} ${toString parallelBuilds} ${toString speedFactor} ${lib.concatStringsSep "," supportedFeatures} - $(echo -n '${publicHostKey}' | base64 -w0)";
+  "ssh://${user}@${host}?remote-store=/mnt ${lib.concatStringsSep "," supportedSystems} ${config.age.secrets.hydra-ssh-key-priv.path} ${toString parallelBuilds} ${toString speedFactor} ${lib.concatStringsSep "," supportedFeatures} - $(echo -n '${publicHostKey}' | base64 -w0)";
 
   # TODO:
   # - generalize to new architectures