russell@unturf.com
d86ef8530f
Against real-world OTP 26 peers the v6 handshake "succeeded" but the first REG_SEND silently dropped on the peer side — peer accepted the connection then closed the link with no bytes when we tried to call a registered process. Hit during MPS↔portal wallet RPC smoke test. Root cause: OTP 25+ requires DFLAG_MANDATORY_25_DIGEST to be present in our advertised flag set. The digest is the hash of the OTP-25 mandatory flag set; without it the peer's dist driver loses confidence in the negotiation and drops messages from us without surfacing an error. Adds DFLAG_MANDATORY_25_DIGEST to DEFAULT_FLAGS. Also extends _decode_message to accept both legacy pass-through (0x70 ...) and dist-header framing (0x83 0x44 0x00 ...) on receive — modern OTP may send dist-headed messages even when we didn't negotiate DFLAG_DIST_HDR_ATOM_CACHE. Fragments (0x83 0x45 / 0x83 0x46) still TODO; we surface a clear ChannelError instead of silent corruption. Send side still uses pass-through framing — we don't yet implement the atom-cache encode/decode that DFLAG_DIST_HDR_ATOM_CACHE would require. Peer routes our pass-through sends without issue. 122/122 tests pass including live integration against a local Erlang node and the TLS dist suite. |
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| docs | ||
| erldistpy | ||
| tests | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| LICENSE | ||
| Makefile | ||
| pyproject.toml | ||
| README.md | ||
erldistpy
Native Python client for our Erlang distribution protocol. Talk Erlang/Elixir nodes from CPython without HTTP shim layers.
Built to swap into Python web apps as a drop-in for HTTP wallet-bridge
clients (see unfeed's
WalletTransport and make_post_sell's crypto watcher) so they can call
Elixir gen_server processes over native Erlang dist instead of JSON-RPC
or HTTPS. Same call semantics, lower latency, fewer moving parts.
Install
pip install erldistpy
Quick start
from erldistpy import Node, Atom
with Node(
our_name="myapp@host",
peer_name="wallet", # short EPMD name
peer_host="wallet.example.com",
cookie="SHARED_COOKIE", # read from a file path, never inline
) as node:
reply = node.call(
"Elixir.Wallet.Service",
(Atom("monero"), Atom("get_height"), []),
timeout=5.0,
)
# reply is whatever the gen_server returned — atoms / binaries /
# tuples / maps / lists / pids / refs decode to Python natives.
For TLS dist (Erlang inet_tls_dist):
from erldistpy import Node, make_dist_tls_context
ctx = make_dist_tls_context(
cert="/etc/myapp/client.pem",
key="/etc/myapp/client.key",
ca="/etc/myapp/ca.pem",
)
node = Node(our_name=..., peer_name=..., cookie=..., tls_context=ctx)
Scope
- ETF (External Term Format) codec — encode/decode Erlang terms
- EPMD client — node name → port lookup
- v6 distribution handshake — MD5 cookie auth, version negotiation
gen_callto registered processes on a remote node- TLS dist support (Erlang
inet_tls_dist)
Out of scope: full Erlang node impersonation, link/monitor lifecycles, distributed Mnesia. We are a client, not a peer node.
Why not Pyrlang?
Pyrlang implements a full asyncio Erlang node. Heavy, asyncio-first,
complex. erldistpy is a small synchronous client that fits behind the
same Protocol surface as httpx. Different shape, different audience.
Development
make bootstrap # create venv, install editable + dev deps
make test # run pytest (122 tests)
make lint # ruff check
make build # build sdist + wheel into dist/
make dist-check # twine check dist/*
See docs/ROADMAP.md for the phase-by-phase build log.
License
Unlicense (public domain).