working garbage collector

hcl/builder.hcl

@@ -125,6 +125,38 @@ job "builder" {
         memory = 4000
     }
   }
+  task "garbage-collect-cache" {
+    driver = "docker"
+    config {
+      image = "nixpkgs/nix:nixos-22.11"
+      args = [ "/tmp/gc.sh" ]
+      volumes = [ 
+        "local/gc.sh:/tmp/gc.sh",
+        "local/nix.conf:/etc/nix/nix.conf",
+        "/var/cache/albatros/nix:/nix",
+      ]
+    }
+
+    lifecycle {
+      hook = "poststop"
+      sidecar = false
+    }
+
+    template {
+      data = file("./nix.conf")
+      destination = "local/nix.conf"
+    }
+
+    template {
+      data = file("./gc.sh")
+      destination = "local/gc.sh"
+      perms = "555"
+    }
+
+    restart {
+      attempts = 0
+    }
+  }
   }
 }
 

hcl/pin.sh

@@ -1,4 +1,9 @@
 #!/usr/bin/env bash
 set -euxo pipefail
+set -f # disable globbing
 
-echo "hook on $DRV_PATH"
+mkdir -p /nix/var/nix/gcroots/albatros
+DRV_NAME=$(echo $DRV_PATH | cut -d '/' -f 4)
+GCROOT=/nix/var/nix/gcroots/albatros/$DRV_NAME
+rm -f $GCROOT
+ln -s $DRV_PATH $GCROOT

main.go

@@ -413,7 +413,7 @@ func main() {
 	http.HandleFunc("/build", build)
 
 	// launch
-	log.Println("Listen on :8080")
+	log.Println("Albatros listen on :8080")
 	if err = http.ListenAndServe(":8080", nil); err != nil {
 		log.Fatal("Can't start HTTP server")
 	}