Codify Tailscale ACL with tag:homelab scaffolding

homelab/tailscale.tf

@@ -14,3 +14,65 @@ resource "tailscale_dns_nameservers" "global" {
 resource "tailscale_dns_preferences" "main" {
   magic_dns = true
 }
+
+# Tailnet policy file. Codifies the current default-allow stance and adds
+# forward-looking structure (tag:homelab, SSH for tagged servers) that no-ops
+# until devices actually advertise the tag.
+#
+# DO NOT tighten the `*:*` rule in the same change that introduces tagging.
+# Switching to a restrictive policy before any device wears tag:homelab will
+# leave the operator unable to reach gandalf over Tailscale. Sequence:
+#   1. (this resource) Codify allow-all + tagOwners + SSH-to-tag-homelab.
+#   2. Advertise tag:homelab on gandalf (`tailscale up --advertise-tags=tag:homelab`)
+#      and approve the tag in the admin UI.
+#   3. Replace the `*:*` rule with restrictive admin/tag-scoped rules.
+resource "tailscale_acl" "main" {
+  acl = jsonencode({
+    tagOwners = {
+      # Servers in the home lab (gandalf today, Pis later). Only tailnet
+      # admins can apply this tag — prevents a random tailnet member from
+      # spoofing a homelab node.
+      "tag:homelab" = ["autogroup:admin"]
+    }
+
+    acls = [
+      # Phase 1: keep the default-allow rule so nothing breaks for current
+      # devices. Replace with restrictive rules in a follow-up PR after
+      # gandalf is tagged.
+      {
+        action = "accept"
+        src    = ["*"]
+        dst    = ["*:*"]
+      },
+    ]
+
+    ssh = [
+      # Tailscale SSH default: members can SSH into their own devices
+      # (the "check" action requires reauth). Carried over from the
+      # admin UI default.
+      {
+        action = "check"
+        src    = ["autogroup:member"]
+        dst    = ["autogroup:self"]
+        users  = ["autogroup:nonroot", "root"]
+      },
+      # Forward-looking: members can SSH into homelab-tagged servers as
+      # `nickv` or `root`. No-op until a device wears tag:homelab.
+      {
+        action = "accept"
+        src    = ["autogroup:member"]
+        dst    = ["tag:homelab"]
+        users  = ["nickv", "root"]
+      },
+    ]
+
+    nodeAttrs = [
+      # Tailscale Funnel — let members expose their own devices to the
+      # public internet. Carried over from the admin UI default.
+      {
+        target = ["autogroup:member"]
+        attr   = ["funnel"]
+      },
+    ]
+  })
+}