tstest/natlab: move running instructions to a README

Updates #cleanup

Change-Id: I9580fbfeeef2edf0c678c8ab1ec70131fd20f0b5
Signed-off-by: Francois Marier <francois@tailscale.com>

tstest/natlab/README.md

@@ -0,0 +1,28 @@
+# natlab
+
+Virtual network lab for integration tests. Tracking issue:
+https://github.com/tailscale/tailscale/issues/13038
+
+Use the `run-natlab-tests` GitHub label on PRs to run these tests.
+
+## Prerequisites
+
+- `qemu-system-x86_64` and `qemu-img`. On Debian/Ubuntu:
+  `apt install qemu-system-x86 qemu-utils`
+- A built gokrazy natlabapp image (auto-built on first run via
+  `make -C gokrazy natlab`)
+
+KVM is used automatically on Linux when `/dev/kvm` is readable+writable. Add
+yourself to the `kvm` group to avoid QEMU falling back to software emulation.
+
+## Running locally
+
+```
+go test ./tstest/natlab/vmtest/ --run-vm-tests -v -timeout=15
+```
+
+`go test`'s default timeout (10 min) is likely not enough to cover the whole
+package. You may need to raise it further or disable the timeout entirely
+(`-timeout=0`) when running the full suite.
+
+Alternatively, select individual tests with the usual `-run`.

tstest/natlab/vmtest/vmtest.go

@@ -6,13 +6,7 @@
 // network infrastructure. It supports mixed OS types (gokrazy, Ubuntu, Debian)
 // and multi-NIC configurations for scenarios like subnet routing.
 //
-// Prerequisites:
-//   - qemu-system-x86_64 (KVM is used automatically on Linux when /dev/kvm is accessible)
-//   - A built gokrazy natlabapp image (auto-built on first run via "make natlab" in gokrazy/)
-//
-// Run tests with:
-//
-//	go test ./tstest/natlab/vmtest/ --run-vm-tests -v
+// See tstest/natlab/README.md for prerequisites and how to run.
 package vmtest
 
 import (