Resolve current system path at runtime for exec driver jobs.

services/resol-gateway.hcl

@@ -12,6 +12,11 @@ job "resol-gateway" {
       read_only = true
       source = "nix-store"
     }
+    volume "sw" {
+      type = "host"
+      read_only = true
+      source = "sw"
+    }
 
     network {
       port "http" {
@@ -23,7 +28,7 @@ job "resol-gateway" {
       driver = "exec"
 
       config {
-        command = "/nix/store/k5inwzpp6a0295pd3nfckk9hq8wmifhz-nodejs-20.15.1/bin/node"
+        command = "/sw/bin/node"
         args = ["/code/resol-vbus/examples/json-live-data-server/index.js"]
       }
 
@@ -35,6 +40,10 @@ job "resol-gateway" {
         volume = "nix-store"
         destination = "/nix/store"
       }
+      volume_mount {
+        volume = "sw"
+        destination = "/sw"
+      }
 
       service {
         name = "resol-gateway"