From 3c1e2c0e761ca41a39c3fc95d11a013172e1bb86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Mon, 15 Jan 2024 13:41:48 +0100
Subject: [PATCH] cleanup drv gcroots after a build

---
 buildbot_nix/__init__.py | 17 +++++++++++++++--
 nix/master.nix           |  7 +++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/buildbot_nix/__init__.py b/buildbot_nix/__init__.py
index 34ae933..3f5fd19 100644
--- a/buildbot_nix/__init__.py
+++ b/buildbot_nix/__init__.py
@@ -377,6 +377,9 @@ def nix_eval_config(
             haltOnFailure=True,
         ),
     )
+    drv_gcroots_dir = util.Interpolate(
+        "/nix/var/nix/gcroots/per-user/buildbot-worker/%(prop:project)s/drvs/",
+    )
 
     factory.addStep(
         NixEvalCommand(
@@ -393,8 +396,7 @@ def nix_eval_config(
                 "accept-flake-config",
                 "true",
                 "--gc-roots-dir",
-                # FIXME: don't hardcode this
-                "/var/lib/buildbot-worker/gcroot",
+                drv_gcroots_dir,
                 "--force-recurse",
                 "--check-cache-status",
                 "--flake",
@@ -405,6 +407,17 @@ def nix_eval_config(
         ),
     )
 
+    factory.addStep(
+        steps.ShellCommand(
+            name="Cleanup drv paths",
+            command=[
+                "rm",
+                "-rf",
+                drv_gcroots_dir,
+            ],
+        ),
+    )
+
     return util.BuilderConfig(
         name=f"{project.name}/nix-eval",
         workernames=worker_names,
diff --git a/nix/master.nix b/nix/master.nix
index 8057f06..6383d5e 100644
--- a/nix/master.nix
+++ b/nix/master.nix
@@ -234,8 +234,11 @@ in
       };
     };
 
-    # Allow buildbot-master to write to this directory
-    systemd.tmpfiles.rules = lib.optional (cfg.outputsPath != null)
+    systemd.tmpfiles.rules = [
+      # delete legacy gcroot location, can be dropped after 2024-06-01
+      "R /var/lib/buildbot-worker/gcroot - - - - -"
+    ] ++ lib.optional (cfg.outputsPath != null)
+      # Allow buildbot-master to write to this directory
       "d ${cfg.outputsPath} 0755 buildbot buildbot - -";
   };
 }