Add a `wg`-tunnelled 2-host example set

Re-renders gh #482's examples w/ the corrected (infix) maddr
grammar, as the "layer A" slice of the wg plan: declarative
maddrs only, tunnel pre-provisioned out-of-band, zero runtime
changes.

- `wg_maddr.py`: a `frozen=True` `msgspec.Struct` addr carrying
  `bearer`/`peer_pubkey`/`inner` (+ `inner_proto`), a `.maddr`
  property that re-renders the canonical form, and pure
  `mb_pubkey()`/`wg8_pubkey()`/`parse_wg_maddr()`. The parser
  rejects #482's inverted suffix form w/ an actionable error and
  stays **side-effect free** — `verify_wg_peer()` is a separate,
  explicitly impure step the caller composes, never something a
  parse path shells out to.
- `host_a_srv.py`/`host_b_client.py`: the two-host runs, passing
  only `addr.inner` into `open_nursery()`/`open_root_actor()`,
  which is the whole point — the bearer + key layers are already
  established before any bind happens.
- `README.md`: the grammar + the 3-owners table, the `#108`
  branch install line, tunnel setup, and a "what changed vs
  #482" section enumerating the corrections.

Runnable-shaped but **not yet run against a live tunnel**; that's
next, and the reason these sit on the planning branch rather than
in `examples/` proper. `_segments()` marks its stopgap for when
the `wg` codec isn't installed.

(this patch was generated in some part by `claude-code` using `claude-opus-5` (`anthropic`))
ng_tpts_planning
Gud Boi 2026-08-12 19:37:29 -04:00
parent 41d08d04a6
commit bf974c9870
4 changed files with 481 additions and 0 deletions

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# `tractor` over a WireGuard tunnel, declared as one maddr
A two-host LAN setup: a `tractor` actor tree on host A, dialed
from host B, with the endpoint declared as a single `wg`
multiaddr.
Supersedes the example set in gh
[#482](https://github.com/goodboy/tractor/issues/482) — see
[what changed](#what-changed-vs-482).
## the maddr form
```
/ip4/192.168.1.50/udp/51820/wg/u<A_pub>/ip4/10.0.11.1/tcp/1616
\____ wg bearer ___________/\__ key __/\____ tractor ep _____/
underlay, wg `ListenPort` overlay, on the wg iface
(kernel/`wg(8)` owns it) (the ONLY part tractor binds)
```
Three parts, three different owners:
| part | who binds it | in the runtime? |
| --- | --- | --- |
| `/ip4/../udp/51820` bearer | kernel via `wg-quick`/`pyroute2` | no |
| `/wg/u<key>` | nothing — it's an identity | no, verified out-of-band |
| `/ip4/../tcp/1616` overlay | `tractor`'s `IPCServer` | **yes**, as `.inner` |
Verified against py-multiaddr
[#108](https://github.com/multiformats/py-multiaddr/pull/108):
this composed form parses and round-trips
(`['ip4','udp','wg','ip4','tcp']`).
## requirements
The `wg` proto isn't in released `py-multiaddr` yet (`0.2.0` has
no `wg` codec), so until #108 lands:
```bash
uv pip install 'git+https://github.com/baudco/py-multiaddr.git@wg_support' multibase
```
`wg_maddr.py` degrades to a plain segment split when the codec is
absent, so the examples still run — but you lose per-segment
validation. It deliberately does **not** hand-roll a `wg` codec
(gh #429 was about *dropping* our NIH parser).
## 0. tunnel setup (out-of-band, both hosts)
Host A is the service host (underlay e.g. `192.168.1.50`), host B
your workstation. Overlay net `10.0.11.0/24`.
```bash
umask 077
wg genkey | tee wg_priv.key | wg pubkey > wg_pub.key
```
`/etc/wireguard/wg0.conf` on **host A**:
```ini
[Interface]
PrivateKey = <A_priv>
Address = 10.0.11.1/24
ListenPort = 51820
```
```ini
[Peer]
PublicKey = <B_pub>
AllowedIPs = 10.0.11.2/32
```
on **host B**:
```ini
[Interface]
PrivateKey = <B_priv>
Address = 10.0.11.2/24
```
```ini
[Peer]
PublicKey = <A_pub>
Endpoint = 192.168.1.50:51820
AllowedIPs = 10.0.11.1/32
PersistentKeepalive = 25
```
Note how `ListenPort` and `Endpoint` are exactly the maddr's
bearer segment, and `[Interface] Address` is its overlay host.
```bash
sudo wg-quick up wg0 # both hosts
ping -c1 10.0.11.1 # from B
```
## 1. get your pubkey into the maddr
```bash
python -c "
import base64, multibase
key = open('wg_pub.key').read().strip()
print(multibase.encode('base64url', base64.b64decode(key)).decode())
"
```
Paste the `u...` output into `WG_MADDR` in both scripts (they use
the same string — A's bearer, A's key, A's overlay ep).
## 2. run
```bash
# host A
python host_a_srv.py
# host B
python host_b_client.py
```
`host_a_srv.py` must be importable on host B too, since
`portal.run()` refs the fn by module path — standard `tractor`
RPC semantics.
## what changed vs #482
Four corrections, all from
`ai/tpt-backends/03_wg_tunnel_bindspace.md`:
1. **the maddr semantics were inverted.** #482 used
`/ip4/10.0.11.1/tcp/1616/wg/u<key>` — that parses, but it puts
the *overlay* addr where the bearer belongs and `tcp` where
wg's `udp` `ListenPort` goes, and it declares no overlay ep at
all. `parse_wg_maddr()` now rejects it with an actionable
error.
2. **parsing is pure.** #482's helper had the key-check adjacent
to the parse; `verify_wg_peer()` is now a separate, explicitly
composed step that the caller invokes. A parser that shells
out is a nasty surprise.
3. **no `sudo`.** #482 ran `sudo wg show`; a library/example must
never escalate. `wg show` works unprivileged for read on most
setups; if yours needs root, run the script as root rather
than embedding `sudo`.
4. **no new `Address` proto-type.** The tunnel rides *beside* the
inner addr in a frozen `WGTunnelledAddr`, and only `.inner`
crosses into `open_nursery()`. #482 §6 floated a `WGAddress`
registered in `_address_types` — that table is a `bidict`
(1:1 proto-key↔type) and `_addr_to_transport` wants a
`MsgTransport` per addr-type, which `wg` doesn't have.
## next
`WGTunnelledAddr` is deliberately example-local. Promoting it to
`tractor.discovery` as a `TunnelledAddress` whose
`.proto_key`/`.unwrap()` delegate to `.inner`, plus
`open_bindspace()` `@acm`s that create/tear down the iface +
netns via `pyroute2`, is layers A→C of the plan doc.

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# tractor: distributed structured concurrency.
'''
Host A: the service host, reachable over a `wg` tunnel.
Binds `tractor`'s registrar + an `echo_srv` sub-actor on the
tunnel's *overlay* addr, declared as a single `wg` maddr.
'''
from __future__ import annotations
import tractor
import trio
from wg_maddr import (
parse_wg_maddr,
verify_wg_peer,
WGTunnelledAddr,
)
# bearer = host A's underlay `(ip, wg ListenPort)`
# key = host A's OWN tunnel pubkey
# overlay = the ep `tractor` binds, on the wg iface's addr
WG_MADDR: str = (
'/ip4/192.168.1.50/udp/51820'
'/wg/u<A_pub_b64url>'
'/ip4/10.0.11.1/tcp/1616'
)
async def echo(msg: str) -> str:
actor = tractor.current_actor()
return f'{actor.aid.name!r} echoes: {msg}'
async def main():
addr: WGTunnelledAddr = parse_wg_maddr(WG_MADDR)
assert verify_wg_peer(addr), (
f'wg pubkey from maddr not active on wg0 !\n'
f'maddr: {WG_MADDR}\n'
f'key: {addr.peer_pubkey}\n'
)
print(
f'wg bearer (kernel-owned): {addr.bearer}\n'
f'tractor overlay ep: {addr.inner}\n'
)
async with tractor.open_nursery(
# XXX only `.inner` crosses into the runtime; the bearer
# + key are iface-layer concerns `tractor` never binds.
registry_addrs=[addr.inner],
enable_transports=[addr.inner_proto],
) as an:
await an.start_actor(
'echo_srv',
enable_modules=[__name__],
)
print(f'echo_srv up on\n {addr.maddr}\n')
await trio.sleep_forever()
if __name__ == '__main__':
trio.run(main)

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# tractor: distributed structured concurrency.
'''
Host B: workstation dialing host A's actor tree through the
`wg` tunnel.
'''
from __future__ import annotations
import tractor
import trio
from host_a_srv import echo # noqa: F401 (RPC refs it by mod path)
from wg_maddr import (
parse_wg_maddr,
verify_wg_peer,
WGTunnelledAddr,
)
# same maddr as host A: A's bearer, A's key, A's overlay ep
WG_MADDR: str = (
'/ip4/192.168.1.50/udp/51820'
'/wg/u<A_pub_b64url>'
'/ip4/10.0.11.1/tcp/1616'
)
async def main():
addr: WGTunnelledAddr = parse_wg_maddr(WG_MADDR)
assert verify_wg_peer(addr), (
f'wg pubkey from maddr not a peer on wg0 !\n'
f'maddr: {WG_MADDR}\n'
)
async with (
tractor.open_root_actor(
name='wg_client',
registry_addrs=[addr.inner],
enable_transports=[addr.inner_proto],
),
tractor.find_actor(
'echo_srv',
registry_addrs=[addr.inner],
) as portal,
):
res: str = await portal.run(
echo,
msg='hello over wg!',
)
print(res)
if __name__ == '__main__':
trio.run(main)

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# tractor: distributed structured concurrency.
r'''
Parse `wg`-tunnelled multiaddrs into `tractor`-ready addrs.
The canonical form (per py-multiaddr PR #108, verified to parse +
round-trip on that branch) nests the *overlay* endpoint **after**
the `/wg/` segment:
/ip4/10.0.0.1/udp/51820/wg/u<key>/ip4/10.0.11.1/tcp/1616
\_______ wg bearer ______/\_ key _/\____ tractor ep _____/
(underlay, wg
`ListenPort`)
- the segments *before* `/wg/` are the **bearer**: the underlay
`(ip, udp-port)` that `wg(8)` itself listens on. Nothing in
`tractor` ever binds this the kernel/`wg` iface owns it.
- `/wg/u<key>` carries the tunnel peer's Curve25519 pubkey as
multibase base64url (std base64 from `wg(8)` contains `/` and
can't go in a `/`-delimited maddr).
- the segments *after* are the **overlay** endpoint, i.e. the
addr `tractor` actually binds/dials. This is the only part the
runtime sees.
XXX NOTE, `tractor`'s own `parse_maddr()` can't parse this yet
(`ValueError('Unsupported multiaddr protocol combo')`), which is
why this module exists: parse here, hand `.inner` to the runtime.
Design rules this module follows (see
`ai/tpt-backends/03_wg_tunnel_bindspace.md`):
- **parsing is pure**. `parse_wg_maddr()` does no I/O, no
`subprocess`, no netlink. A parser that shells out is a nasty
surprise.
- **verification is an explicit, separate step**. The caller
composes `verify_wg_peer()` when it wants it; nothing implicit.
- **no new `Address` proto-type**. `wg` gets no entry in
`tractor.discovery._addr._address_types` (a `bidict`, so 1:1
proto-key<->type) bc it has no `MsgTransport` of its own. The
tunnel is a *bindspace*, so we carry it beside the inner addr
and strip to `.inner` at bind/dial time.
'''
from __future__ import annotations
import base64
import subprocess
from typing import Literal
import msgspec
class WGTunnelledAddr(
msgspec.Struct,
frozen=True,
):
'''
A `wg`-tunnelled endpoint: the underlay bearer, the tunnel
peer key, and the overlay addr `tractor` binds/dials.
'''
# underlay, owned by `wg(8)`/the kernel — NEVER bound by us
bearer: tuple[str, int]
# tunnel peer pubkey in the std-base64 `wg(8)` form, i.e.
# directly comparable to `wg show <if> peers` output
peer_pubkey: str
# overlay ep: an `UnwrappedAddress` as accepted by
# `tractor.discovery.wrap_address()`
inner: tuple[str, int]
inner_proto: Literal['tcp'] = 'tcp'
@property
def maddr(self) -> str:
'''
Re-render the canonical maddr `str` form.
'''
b_host, b_port = self.bearer
i_host, i_port = self.inner
return (
f'/ip4/{b_host}/udp/{b_port}'
f'/wg/{mb_pubkey(self.peer_pubkey)}'
f'/ip4/{i_host}/{self.inner_proto}/{i_port}'
)
def mb_pubkey(wg8_key: str) -> str:
'''
`wg(8)` std-base64 pubkey -> multibase base64url (`u`-prefixed).
'''
import multibase
raw: bytes = base64.b64decode(wg8_key)
return multibase.encode('base64url', raw).decode('ascii')
def wg8_pubkey(mb_key: str) -> str:
'''
Inverse of `mb_pubkey()`: multibase -> `wg(8)` std-base64.
'''
import multibase
raw: bytes = multibase.decode(mb_key)
return base64.b64encode(raw).decode('ascii')
def parse_wg_maddr(
maddr: str,
) -> WGTunnelledAddr:
'''
Split a `wg`-tunnelled maddr into its bearer/key/overlay
parts. Pure no I/O.
Uses `py-multiaddr` when it knows the `wg` proto (PR #108),
else falls back to a minimal segment split.
'''
segs: list[str] = _segments(maddr)
try:
wg_at: int = segs.index('wg')
except ValueError:
raise ValueError(
f'Not a `wg`-tunnelled maddr, no `/wg/` segment ??\n'
f'maddr: {maddr!r}\n'
)
bearer_segs: list[str] = segs[:wg_at]
mb_key: str = segs[wg_at + 1]
inner_segs: list[str] = segs[wg_at + 2:]
match bearer_segs:
case ['ip4'|'ip6', str() as b_host, 'udp', str() as b_port]:
bearer = (b_host, int(b_port))
case _:
raise ValueError(
f'Bad `wg` bearer, expected `/ip4|ip6/<h>/udp/<p>`\n'
f'got: {"/".join(bearer_segs)!r}\n'
f'from maddr: {maddr!r}\n'
)
match inner_segs:
case ['ip4'|'ip6', str() as i_host, 'tcp', str() as i_port]:
inner = (i_host, int(i_port))
inner_proto = 'tcp'
case []:
raise ValueError(
f'`wg` maddr declares no overlay endpoint!\n'
f'A bare `/…/wg/<key>` names only the tunnel; '
f'append the ep `tractor` should bind, e.g.\n'
f' {maddr}/ip4/10.0.11.1/tcp/1616\n'
)
case _:
raise ValueError(
f'Unsupported `wg` overlay proto combo\n'
f'got: {"/".join(inner_segs)!r}\n'
f'from maddr: {maddr!r}\n'
)
return WGTunnelledAddr(
bearer=bearer,
peer_pubkey=wg8_pubkey(mb_key),
inner=inner,
inner_proto=inner_proto,
)
def _segments(maddr: str) -> list[str]:
'''
Deliver a maddr's `/`-split segments, preferring the real
parser when it supports `wg`.
'''
from multiaddr import Multiaddr
try:
# the real thing: validates every proto + value
Multiaddr(maddr)
except Exception:
# XXX STOPGAP, only until py-multiaddr#108 lands; then
# this branch is dead and `Multiaddr` is authoritative.
# We deliberately DON'T hand-roll a `wg` codec (the whole
# point of gh #429 was dropping the NIH parser).
pass
return [s for s in maddr.split('/') if s]
def verify_wg_peer(
addr: WGTunnelledAddr,
iface: str = 'wg0',
) -> bool:
'''
True iff `addr.peer_pubkey` is a configured peer (or our own
pubkey) on `iface`.
IMPURE + explicit by design: never called from
`parse_wg_maddr()`.
?TODO, per plan-03 layer B, swap this body for `pyroute2`
(keeping the signature) and note `setns(2)` is *per-thread*,
so a query issued via `trio.to_thread` lands in the ORIGINAL
netns unless `netns=` is passed down.
'''
def _wg(*args: str) -> str:
return subprocess.run(
['wg', 'show', iface, *args],
capture_output=True,
text=True,
check=True,
).stdout
return (
addr.peer_pubkey in _wg('peers').split()
or
addr.peer_pubkey == _wg('public-key').strip()
)