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#!/usr/bin/env python3
"""hello-node — the smallest program that is a real LSPO external step.
It reads its inputs, VERIFIES each one against the hash and the size the orchestrator
pinned for it, copies each one into its output area, writes a small report, and finishes
by writing the completion marker.
**This file deliberately imports nothing from the orchestrator, and nothing from PyPI.**
Copy it into your own repository and start editing: the contract is four JSON documents
and a directory, not a library. The standard library is the whole dependency list, and
that is not an aesthetic choice — see `Why no HTTP library`_ below.
What the orchestrator gives you
-------------------------------
``LSPO_CREDENTIALS_FILE`` names a JSON file the agent mounts read-only. It carries a
short-lived way to read your inputs and write your outputs, and nothing else::
{
"schema_version": 1,
"scheme": "s3", # or "local" in single-host demo mode
"expires_at": "2026-08-07T12:00:00+00:00",
"manifest_get": "https://…", # ("manifest_path": "/…" when local)
"inputs": [{"name": …, "relpath": …, "sha256": …, "size": …, "get_url": …}],
"staging": {"mode": "presigned_post",
"post": {"url": …, "fields": {…}, "key_prefix": "…/"}}
}
The manifest (``invocation.json``) describes the job: your ``params``, the pinned
input objects, the attempt and generation, the runtime budget.
What you must give back
-----------------------
Anything you like, under your staging prefix, and then ``__lspo_complete.json``:
{"schema_version": 1, "execution_id": …, "attempt": …, "generation": …,
"status": "succeeded", "exit_code": 0,
"objects": [{"relpath": "outputs/x.csv", "sha256": "…", "size": 123}],
"produced_ports": {"output": ["outputs/x.csv"]}}
**Write the marker LAST.** Its existence is the orchestrator's proof that everything
it lists is already readable — write it early and a half-finished run is
indistinguishable from a complete one. Every object you name in ``produced_ports``
must also appear in ``objects``, with its real hash and size: collection re-reads
every one of them and refuses to publish anything if a single hash disagrees.
Exit codes: 0 succeeded, 1 retry me, 10 do not retry, 20 cancelled.
The five things this file does that a first version always leaves out
---------------------------------------------------------------------
Each of them is a RECOMMENDATION in the documents — nothing in the platform checks any
of them — and each is the difference between a node that works on the demo and one that
survives a real job. ``docs/AUTHORING.md`` explains every one at length.
1. **It streams, in both directions, and never holds an object in memory.** A single
object may legally be 1 GiB while the container's default memory limit is 2 GiB, so
holding one as bytes and again as a request body is an out-of-memory kill — and an
OOM kill leaves no chance to write a marker at all.
2. **It re-reads its credentials.** The agent replaces the file underneath a running
container, atomically and with no signal. A node that reads it once cannot upload
its outputs, or its own marker, after about fifteen minutes.
3. **It keeps its inventory where the failure path can see it.** Salvage publishes only
what the marker lists, so an inventory local to the work function strands everything
already uploaded.
4. **It handles a stop request, and notices it without waiting for the network.** This
process is PID 1 in its container, and Linux gives process 1 no default signal
handling: without a handler, SIGTERM is discarded entirely and the step runs to
completion for a run nobody will collect. Installing the handler is only half of it —
a step that installs one and then sits in a socket call until it times out has spent
the whole of a grace it was never promised, so the handler also abandons the transfer
in flight. See :class:`_StoppableTransport` for what that takes and what the obvious
version of it does instead, which is nothing.
5. **It never prints a credential.** A presigned URL's query string IS a read credential
for that object, and container output is stored with the execution, shown to everyone
who can see the run, and searchable.
.. _Why no HTTP library:
Why no HTTP library
-------------------
This file used to depend on ``requests``, and that dependency quietly contradicted point
1 above. ``requests`` builds a multipart upload body by concatenating it in memory
(``urllib3.filepost.encode_multipart_formdata``), so ``files={'file': ...}`` holds the
whole object — the very thing the 1 GiB-object-against-2 GiB-of-memory warning is about.
Streaming an upload with it needs a further dependency (``requests_toolbelt``). The
standard library can do it in about sixty lines, which is what :class:`_MultipartBody`
and :func:`_post_object` are, so the dependency list is empty and the recommendation is
actually followed.
"""
from __future__ import annotations
import contextlib
import datetime
import hashlib
import http.client
import io
import json
import logging
import os
import re
import signal
import socket
import sys
import tempfile
import threading
import time
import urllib.error
import urllib.request
MARKER_FILENAME = '__lspo_complete.json'
RESULT_FILENAME = 'result.json'
OUTPUT_PORT = 'output'
REPORT_PORT = 'report'
OUTPUT_DIR = 'outputs'
#: The variable the agent sets for every job. This is the one to read.
CREDENTIALS_ENV = 'LSPO_CREDENTIALS_FILE'
#: A name only this repository's own images ever set. Kept working on purpose; see
#: :func:`resolve_credentials_path`.
LEGACY_CREDENTIALS_ENV = 'LSPO_CREDENTIALS'
#: Where the orchestrator mounts credentials when the envelope says nothing
#: (``external/contract.py`` ``DEFAULT_CREDENTIALS_FILE``).
DEFAULT_CREDENTIALS_FILE = '/lspo/creds/creds.json'
EXIT_OK = 0
EXIT_TRANSIENT = 1
EXIT_PERMANENT = 10
EXIT_CANCELLED = 20
#: The contract refuses a job description or a marker above this.
MAX_DOCUMENT_BYTES = 8 * 1024 * 1024
#: ``result.json`` is a contract document and its reader is bounded at 1 MiB. Writing a
#: bigger one publishes something the other side is forbidden to read.
MAX_RESULT_BYTES = 1024 * 1024
#: The upload policy refuses a single object above this.
MAX_OBJECT_BYTES = 1024 * 1024 * 1024
#: Socket timeout for one read. It bounds a store that has gone quiet — NOT how long a
#: stop takes to be noticed, which is what this constant used to claim. A stop is noticed
#: at once, because the handler shuts the socket down underneath the call
#: (:class:`_StoppableTransport`); this number is what is left for the case where nobody
#: signalled anything and the other side simply stopped answering.
READ_TIMEOUT_S = 25.0
#: An ELAPSED deadline for getting a connection — the name lookup, every address tried,
#: and the TLS handshake that follows, together. It exists because that whole stretch is
#: the one a stop CANNOT interrupt: it hands out no socket anybody else can reach, and
#: Python's ``ssl`` detaches the plain socket while it wraps it, so shutting that down
#: raises "Bad file descriptor" rather than ending the handshake (measured). What cannot
#: be interrupted has to be bounded.
#:
#: **Elapsed, and that word is the whole of it.** Passing a timeout to
#: ``socket.create_connection`` does NOT bound this: it resolves the name first, with no
#: timeout applied to that at all, and then applies the value **separately to each address
#: it got back** — so a slow resolver is unbounded and a host with four addresses can take
#: four times what you thought you asked for. :func:`_connect_within` is what makes one
#: number mean one number. The handshake that follows inherits whatever is left of it.
#:
#: **Ten seconds, and it is chosen against what a real job needs, not against what makes a
#: test quick.** Reaching an object store is milliseconds, so this is enormous headroom —
#: deliberately, because the cost of being wrong is asymmetric in a way that is easy to get
#: backwards. A deadline that fires on a healthy-but-slow connect **kills the whole job**:
#: there is no automatic retry engine for external steps, every failed attempt is recorded
#: as transient whatever this process returns, and somebody has to notice and retry it by
#: hand (``docs/PROTOCOL.md`` section 6). A deadline that is generous costs, at worst, ten
#: seconds of a stop nobody was promised any of. Ten is the point where a stall is
#: unambiguous and a working network is nowhere near.
CONNECT_DEADLINE_S = 10.0
#: Socket timeout for one upload — deliberately shorter, because an upload's ending is the
#: ambiguous one. Once the body has been sent the store may already have committed the
#: object, so waiting longer buys only a clearer answer about something that has already
#: happened, and this step has recorded that object either way.
UPLOAD_TIMEOUT_S = 10.0
#: An ELAPSED deadline for writing the completion receipt, covering the connection and the
#: upload together. The receipt is the one thing this step will not abandon on a stop, so
#: it is the one thing that needs its own clock: :data:`UPLOAD_TIMEOUT_S` bounds a socket
#: going QUIET, not a transfer taking long, and a peer that sends a byte every few seconds
#: keeps a connection alive for as long as it likes.
#:
#: Twenty seconds is this node's best-effort budget, not the platform's stop allowance.
#: The current agent can receive a runtime stop window (180 seconds plus 60 for reporting
#: by default). The envelope expiry is clamped to the reporting cutoff, not a contract
#: identifying the workload's earlier kill cutoff; the stop instruction is not forwarded.
#: A late signal or a fence may leave no usable time. Keep this transfer bounded without
#: claiming that its local deadline guarantees the receipt survives a stop.
RECEIPT_DEADLINE_S = 20.0
#: Every streaming copy moves this much at a time.
CHUNK_BYTES = 1024 * 1024
#: How much a streaming copy may leave in the kernel's page cache before asking for it
#: back. See :func:`_release_page_cache` — this is not a performance knob.
CACHE_DROP_BYTES = 8 * 1024 * 1024
#: Re-read the envelope this long before it says it expires.
CREDS_MARGIN_S = 5.0
USER_AGENT = 'lspo-hello-node/2 (+https://github.com/HumanSignal/orchestrator-hello-node)'
class StepError(Exception):
"""Something no retry can fix: a bad input, a bad document, a bad configuration."""
class TransientError(Exception):
"""Something a later attempt might survive: a timeout, a 5xx, an expired signature."""
class _Expired(TransientError):
"""A refusal that looks like expired or rejected credentials."""
# ------------------------------------------------------------------ cancellation
#: Set by the signal handler; read by ordinary control flow. Never do work in a handler.
CANCELLED = False
#: The transport of the request in flight — one, because this program makes exactly one
#: request at a time. A copy of this file that overlaps requests needs a set here instead.
_IN_FLIGHT: list = []
#: Whether the handler may still abandon what is in flight. It may not once the receipt is
#: being written: by then there is nothing left to rescue by cutting a connection, and a
#: whole run's account of itself to lose. A second stop CAN arrive — the agent asks for one
#: from three different places — and the kill behind it is what bounds this wait anyway.
_ABANDONABLE = True
class _StoppableTransport:
"""An HTTP connection the stop handler can reach — for every wait that can be reached.
Mixed into whatever connection class urllib chose (:func:`_stoppable_version_of`).
This file's first attempt kept the RESPONSE object on the ledger and called
``close()`` on it, and that fails twice over:
* **Too late.** A response exists only once the store has begun to answer, so a stop
landing while the step was still waiting for the first byte of a GET reached nothing
at all, and was noticed only when the socket timed out — measured at the full length
of a held-open response under the harness's thirty-second grace. That test
allowance is not the deployed platform's remaining stop time.
* **Wrong call.** ``close()`` does not interrupt a read that is ALREADY blocked.
Measured: mid-body it raises ``RuntimeError: reentrant call inside
<_io.BufferedReader>`` from inside the handler — where the exception is swallowed —
and the read then waits out its whole timeout regardless. ``shutdown()`` makes the
pending call return immediately, which is the entire point of keeping this ledger.
**The same question has to be asked of every OTHER wait on this path**, which is what
the shape below is about. There are four, and they are not alike:
1. **DNS, the TCP connect and the TLS handshake.** All three happen inside one call,
which hands out no socket anybody else can reach: ``ssl`` detaches the plain socket
while it wraps it, so shutting that down raises ``OSError: [Errno 9] Bad file
descriptor`` instead of ending the handshake (measured — the handshake then ran to
the full read timeout regardless). Nothing here can be interrupted, so it is
BOUNDED instead, by :data:`CONNECT_DEADLINE_S` — one ELAPSED deadline over the
lookup, every address and the handshake, because the timeout the standard library
accepts here is none of those things (:func:`_connect_within`). The flag is
re-checked the instant the call returns, so a stop that arrived during it does not
go on to start a request nobody wants.
2. **Waiting for the store to begin answering.** Interruptible, and the reason the
connection goes on the ledger before a byte is sent rather than after.
3. **Reading the body.** Interruptible — but only if the connection is still ON the
ledger, which is why there is no ``close()`` override here. ``http.client``
calls ``close()`` on the connection as soon as the headers of a ``will_close``
response are parsed (and urllib sets ``Connection: close`` on every request), so
removing the entry there would empty the ledger for the whole of the body.
4. **Waiting for a store to acknowledge an upload.** Interruptible, same mechanism.
The socket is also remembered in an attribute of our own, because urllib drops its
reference to it the moment the response exists (``h.sock = None``, in
``AbstractHTTPHandler.do_open``) while the response goes on reading through it.
"""
def connect(self):
# On the ledger BEFORE the call that blocks rather than after it. Be exact about
# what that buys, because the obvious claim is wrong: nothing can be shut down
# during the call below — there is no socket yet, and the one ``ssl`` builds is
# detached from this object while it handshakes (note 1). What bounds that stretch
# is the deadline, and what acts on a stop is the check after it. The entry is
# still made here because the ledger should never say "nothing in flight" while a
# transfer is being set up, and it costs one assignment.
_IN_FLIGHT[:] = [self]
wanted = self.timeout
self._deadline = time.monotonic() + CONNECT_DEADLINE_S
# ``_create_connection`` is an instance attribute ``http.client`` sets in its own
# ``__init__``, so this replaces it rather than overriding a method — a method
# would be shadowed by that attribute and silently never called.
self._create_connection = lambda address, timeout, source=None: _connect_within(
address, self._deadline, source
)
super().connect()
# Getting here was the deadline's business. Everything after it is a transfer, and
# transfers get the timeout the caller asked for.
if wanted:
self.sock.settimeout(wanted)
self._transport = self.sock
if CANCELLED:
# The stop landed inside a phase nothing could interrupt. It is over now, and
# this is the first moment ordinary control flow gets a say: do not go on to
# send a request for a run that has been called off. The receipt is exempt —
# it is the one request a cancelled run still has to make.
if _ABANDONABLE:
raise _Stopped('stop requested while this connection was being made')
def _tunnel(self):
"""Granting the tunnel spends the deadline too, so what follows gets what is LEFT.
With a proxy configured there are TWO waits inside one ``connect``: the proxy's
answer to ``CONNECT``, and then the TLS handshake through it. The socket's timeout
was set once, on the way out of the TCP connect, and TLS would otherwise re-use
that whole value — so a proxy taking nine seconds of a ten-second deadline left the
handshake nearly ten more, and the number meant nothing again. One deadline, read
twice.
"""
super()._tunnel()
deadline = getattr(self, '_deadline', None)
if deadline is not None and self.sock is not None:
self.sock.settimeout(max(0.05, deadline - time.monotonic()))
def stop_now(self) -> None:
"""Make whatever the main thread is waiting for on this socket return, now."""
transport = self.sock or getattr(self, '_transport', None)
if transport is not None:
transport.shutdown(socket.SHUT_RDWR)
def _resolve_within(host: str, port, deadline: float) -> list:
"""Look the host up, and give up if the resolver does not answer in time.
**The only thread in this program, and it is here because the standard library gives
no other way.** ``socket.getaddrinfo`` takes no timeout: it is a blocking call into
the system resolver, whose own limits come from ``/etc/resolv.conf`` and are typically
several seconds per nameserver, tried more than once. A container with a sick resolver
therefore stalls for tens of seconds inside a call that owns no socket — so a stop
cannot be acted on, and the completion receipt, which by then must not be abandoned,
cannot be written either. Handing the lookup to a thread is what turns that into a
number.
The thread is a daemon and is never joined beyond the deadline: a stuck lookup ends
when the resolver finally answers, writing into a list nobody reads. That is a leak of
one thread on a path that is already failing, and the alternative is having no bound at
all on the phase that most often hangs.
"""
found: list = []
failed: list = []
def look_up() -> None:
try:
found.extend(socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM))
except Exception as exc: # noqa: BLE001 — reported to the caller, never swallowed
failed.append(exc)
thread = threading.Thread(target=look_up, daemon=True)
thread.start()
thread.join(max(0.0, deadline - time.monotonic()))
if found:
return found
if failed:
raise TransientError(f'the name {host!r} could not be resolved: {redact(failed[0])}')
raise TransientError(
f'the name {host!r} was still being looked up {CONNECT_DEADLINE_S:.0f}s after this '
f'connection was started'
)
def _connect_within(address, deadline: float, source_address=None) -> socket.socket:
"""``socket.create_connection`` with ONE deadline over the whole thing.
The standard library's version takes a timeout and spends it more than once: the name
lookup happens first with nothing applied to it, and then the value is set on each
address in turn, so four addresses mean four times the wait. This one resolves within
the deadline and gives every attempt only what is left of it.
The socket handed back carries the remainder as its own timeout, which is what the TLS
handshake will then use — so the honest worst case for the whole establish phase is
the deadline plus one handshake operation, rather than a multiple of it.
"""
host, port = address
refusals: list = []
for family, kind, proto, _canonical, sockaddr in _resolve_within(host, port, deadline):
left = deadline - time.monotonic()
if left <= 0:
break
connection = socket.socket(family, kind, proto)
try:
connection.settimeout(left)
if source_address:
connection.bind(source_address)
connection.connect(sockaddr)
except OSError as exc:
refusals.append(exc)
connection.close()
continue
connection.settimeout(max(0.05, deadline - time.monotonic()))
return connection
if refusals:
raise refusals[-1]
raise TimeoutError(
f'no address for {host!r} could be connected to within {CONNECT_DEADLINE_S:.0f}s'
)
#: Cache of the stoppable subclass built for each connection class urllib hands us.
_STOPPABLE_CLASSES: dict = {}
def _stoppable_version_of(connection_class):
"""The stoppable version of one of urllib's connection classes.
Built by subclassing whatever urllib passed rather than by naming
``http.client.HTTPSConnection`` here, so this file never restates the keyword
arguments urllib gives its own connection classes — those have changed between Python
versions, and a node that reimplemented them would break on the next one.
"""
made = _STOPPABLE_CLASSES.get(connection_class)
if made is None:
made = _STOPPABLE_CLASSES[connection_class] = type(
'_Stoppable' + connection_class.__name__, (_StoppableTransport, connection_class), {}
)
return made
def _on_stop(signum, _frame):
"""Set the flag, abandon the transfer in flight, and return. Nothing else.
**RECOMMENDATION, and the one place this file reads the guidance rather than quoting
it.** ``docs/AUTHORING.md`` says a signal handler sets a flag and does no work, "and
especially network work". Shutting down a socket is a single non-blocking syscall: it
starts nothing, waits for nothing and cannot block, so it is not work in the sense the
rule is about. The reason the rule gives — that the cancellation path itself crashes —
is why the flag is set FIRST and why the shutdown's failure is ignored: if it does not
work, this step is exactly as stopped as it would have been without it, and ordinary
control flow still sees the flag at its next check. Without the shutdown the flag is
the only mechanism, and a flag cannot be read by a process parked in a socket call.
Everything that DECIDES anything still happens in ordinary control flow.
"""
global CANCELLED
CANCELLED = True
if _ABANDONABLE:
for transport in list(_IN_FLIGHT):
with contextlib.suppress(Exception):
transport.stop_now()
with contextlib.suppress(Exception):
sys.stderr.write(f'hello-node: stop requested (signal {signum}); finishing up\n')
sys.stderr.flush()
@contextlib.contextmanager
def _within(seconds: float, what: str):
"""Bound everything inside this block by ELAPSED time, network calls included.
A socket timeout is not a deadline: it measures silence, so a peer that dribbles one
byte per window holds a transfer open indefinitely without ever being idle. The alarm
is what turns "no long silences" into "no long transfer", and it reaches a blocked
socket call the same way the stop handler does — by shutting the transport down, which
is the one thing that makes a syscall already in progress return.
Used for the receipt, which is the transfer this step has promised not to abandon on a
stop. That promise is what makes an upper bound necessary rather than merely tidy: the
kill behind the stop arrives on its own schedule, and a step still politely waiting on
a store when it lands has written nothing and said nothing.
"""
def _out_of_time(_signum, _frame):
for transport in list(_IN_FLIGHT):
with contextlib.suppress(Exception):
transport.stop_now()
with contextlib.suppress(Exception):
sys.stderr.write(f'hello-node: giving up on {what} after {seconds:.0f}s\n')
sys.stderr.flush()
previous = signal.signal(signal.SIGALRM, _out_of_time)
signal.setitimer(signal.ITIMER_REAL, seconds)
try:
yield
finally:
signal.setitimer(signal.ITIMER_REAL, 0)
signal.signal(signal.SIGALRM, previous)
class _Stopped(Exception):
"""Raised by ordinary control flow once the flag is seen."""
def _check_stopped() -> None:
if CANCELLED:
raise _Stopped('stop requested')
# --------------------------------------------------------------------- logging
# Everything this program writes to stdout or stderr is captured by the runner, sent to
# the orchestrator and shown in the run's log — so `print()` works, and so does `logging`
# ONCE IT IS CONFIGURED. Without this line a bare `log.info(...)` prints NOTHING: Python's
# default emits WARNING and above, and only to stderr. That is the single most common
# reason a node author says "my logs disappeared".
#
# One thing NOT to write here: secrets. Whatever this program prints is stored with the
# execution, shown to anyone who can see the run, and searchable — so no tokens, no
# credentials, no customer data you would not put in a ticket. The credentials this step
# is handed are short-lived, but a leaked one is still a leak. Everything below goes
# through `redact()` for exactly that reason.
logging.basicConfig(level=logging.INFO, stream=sys.stdout, format='%(levelname)s %(message)s')
log = logging.getLogger('hello-node')
_URL_RE = re.compile(r'\b(?:https?|s3)://[^\s\'"<>|\\]+', re.IGNORECASE)
def redact(text: object) -> str:
"""Reduce every URL to scheme, host and path.
A presigned URL's query string is the credential. The natural way to report a failed
fetch — letting the exception's own text through — is exactly what publishes it,
because HTTP libraries build that text out of the URL.
"""
def _strip(match: re.Match) -> str:
url = match.group(0)
for separator in ('?', '#'):
cut = url.find(separator)
if cut != -1:
return url[:cut] + separator + 'REDACTED'
return url
return _URL_RE.sub(_strip, str(text)).replace('\r', ' ').strip()
_progress_sent = 0
def progress(fraction: float, phase: str) -> None:
"""The one stdout line the agent consumes as progress.
A run that emits none is indistinguishable from a stuck one, which is the only
thing an operator watching a long step has to go on. The shape is exact: the
prefix ``@lspo:progress `` including its trailing space, then a JSON object whose
``fraction`` is between 0.0 and 1.0.
"""
global _progress_sent
if _progress_sent > 200: # a log is a tail of 1000 lines; do not spend it on this
return
_progress_sent += 1
payload = json.dumps({'fraction': round(max(0.0, min(1.0, float(fraction))), 4),
'phase': str(phase)[:64]})
sys.stdout.write('@lspo:progress ' + payload + '\n')
sys.stdout.flush()
# ----------------------------------------------------------------- credentials
def resolve_credentials_path() -> str:
"""Where the credentials file is, and a warning when the two names disagree.
``LSPO_CREDENTIALS_FILE`` is the one the agent sets, for every job, and its value is
the path the ORCHESTRATOR chose — so it wins. ``LSPO_CREDENTIALS`` is a name only
this repository's own older images set; it is honoured when it is the only one
present, because images that bake it are in the field. With neither set, the
contract's own default path is a better answer than giving up.
The disagreement warning names the two VARIABLES and never their values: a path is
not a secret, but a habit of printing whatever is in an environment variable is how
one eventually gets printed. It stays quiet when they agree — a line that appears on
every run is not a warning, it is the noise that teaches people to skip the first ten
lines of a log.
"""
current = os.environ.get(CREDENTIALS_ENV)
legacy = os.environ.get(LEGACY_CREDENTIALS_ENV)
if current and legacy and os.path.normpath(current) != os.path.normpath(legacy):
log.warning(
'%s and %s name different files; using %s, which is the one the agent sets',
CREDENTIALS_ENV, LEGACY_CREDENTIALS_ENV, CREDENTIALS_ENV,
)
if current:
return current
if legacy:
return legacy
return DEFAULT_CREDENTIALS_FILE
def _parse_iso8601(value: object) -> float:
"""ISO 8601 to epoch seconds. Unparseable means "treat it as already stale"."""
if not isinstance(value, str) or not value.strip():
return 0.0
text = value.strip()
if text.endswith(('Z', 'z')):
text = text[:-1] + '+00:00'
try:
parsed = datetime.datetime.fromisoformat(text)
except ValueError:
return 0.0
if parsed.tzinfo is None:
parsed = parsed.replace(tzinfo=datetime.timezone.utc)
return parsed.timestamp()
class Credentials:
"""The envelope, re-read whenever it is at or near its stated expiry.
The agent asks for a fresh envelope shortly before the current one dies and replaces
``creds.json`` atomically underneath the container, by writing a new file and renaming
it over the old one. **You are not signalled.** The directory is mounted rather than
the file precisely so that the replacement is visible to a process that reads the path
again — so an accessor like this one, rather than a variable in ``main()``, is the
whole difference between a node that can upload after fifteen minutes and one that
cannot.
"""
def __init__(self) -> None:
self.path = resolve_credentials_path()
self._envelope: dict | None = None
self._expires_at = 0.0
def get(self, *, force: bool = False, allow_stale: bool = False) -> dict:
if force or self._envelope is None or time.time() >= self._expires_at - CREDS_MARGIN_S:
try:
envelope = self._load()
except Exception:
# Falling back is for one caller only: the marker. A presigned URL keeps
# working until its own expiry whatever happens to the file it came out
# of, and a run that can still explain itself is worth more than one that
# cannot. Everywhere else a vanished credentials file stops the work,
# because it is the platform's signal that this attempt is over.
if self._envelope is None or not allow_stale:
raise
log.warning('the credentials file could not be re-read; '
'attempting the marker with the envelope already held')
return self._envelope
self._envelope = envelope
self._expires_at = _parse_iso8601(envelope.get('expires_at'))
return self._envelope
def _load(self) -> dict:
try:
with open(self.path, 'rb') as handle:
raw = handle.read(64 * 1024 * 1024)
except FileNotFoundError:
raise TransientError(
f'no credentials file at the path {CREDENTIALS_ENV} names; '
f'the agent did not mount one, or this job is no longer its'
)
except OSError as exc:
raise TransientError(f'the credentials file could not be read: {redact(exc)}')
try:
envelope = json.loads(raw.decode('utf-8'))
except Exception as exc:
raise TransientError(f'the credentials file is not valid JSON: {redact(exc)}')
if not isinstance(envelope, dict):
raise TransientError('the credentials file is not a JSON object')
version = envelope.get('schema_version', 1)
if not _is_int(version) or version != 1:
raise StepError(f'credentials envelope schema_version {version!r} is not supported')
staging = envelope.get('staging')
if not isinstance(staging, dict) or staging.get('mode') not in ('local_path', 'presigned_post'):
raise StepError('the credentials envelope carries no staging area this step can write to')
return envelope
def _is_int(value: object) -> bool:
"""A real JSON integer. In Python ``True == 1``, which is the trap this closes."""
return isinstance(value, int) and not isinstance(value, bool)
def _release_page_cache(handle, *, sync: bool = False) -> None:
"""Ask the kernel to drop the pages this file has put in the cache.
**Streaming is not enough on its own.** The container's memory limit counts the page
cache created by its own reads and writes, so a step that never holds more than one
block in memory can still be OOM-killed for moving a large object through a temporary
file: the program's own footprint stays flat while the kernel's cache for that file
grows to the size of the object. This was measured — a 128 MiB input through a 64 MiB
container is killed without this call and survives with it.
Dirty pages cannot be dropped, which is why a write has to be flushed and synced
first. Reads need no sync. Both are best-effort: ``posix_fadvise`` is advice, and it
does not exist everywhere, so a platform without it simply keeps its cache.
"""
try:
if sync:
handle.flush()
os.fsync(handle.fileno())
os.posix_fadvise(handle.fileno(), 0, 0, os.POSIX_FADV_DONTNEED)
except (AttributeError, OSError, ValueError):
pass
# ------------------------------------------------------------------------- http
def _http_error_detail(exc: urllib.error.HTTPError) -> str:
"""A short, URL-free description of a refusal, including the store's own error code."""
body = ''
with contextlib.suppress(Exception):
body = exc.read(4096).decode('utf-8', 'replace')
with contextlib.suppress(Exception):
exc.close()
code = re.search(r'<Code>([^<]{1,64})</Code>', body)
if code:
return f'HTTP {exc.code} {exc.reason} ({code.group(1)})'
if body.strip():
return f'HTTP {exc.code} {exc.reason} ({redact(" ".join(body.split())[:160])})'
return f'HTTP {exc.code} {exc.reason}'
#: Store error codes that mean "this could work if you tried again", even though they can
#: arrive with a 4xx status that would otherwise read as final.
_RETRYABLE_CODES = ('slowdown', 'requesttimeout', 'operationaborted', 'requestthrottled',
'throttling', 'toomanyrequests', 'internalerror', 'serviceunavailable')
#: …and the ones that mean the credential is dead, so re-reading the file may help.
_EXPIRED_CODES = ('expired', 'accessdenied', 'invalidaccesskeyid', 'signaturedoesnotmatch',
'tokenrefreshrequired', 'requesttimetooskewed', 'authorization')
def _classify(exc: urllib.error.HTTPError, detail: str, what: str) -> Exception:
"""Turn one refusal into the right exception, which decides the exit code.
Getting this wrong is not cosmetic: reporting a momentary 503 from an object store as
permanent tells the platform never to run this work again.
"""
flat = detail.lower().replace(' ', '')
message = f'{what} was refused: {detail}'
if exc.code in (400, 401, 403) and any(code in flat for code in _EXPIRED_CODES):
return _Expired(message)
if exc.code >= 500 or exc.code == 429 or any(code in flat for code in _RETRYABLE_CODES):
return TransientError(message)
if 300 <= exc.code < 400:
return TransientError(message)
return StepError(message)
class _NoRedirects(urllib.request.HTTPRedirectHandler):
"""Refuse a redirect rather than silently turning a POST into a bodyless GET.
urllib answers 301/302/303 by re-issuing the request as a GET with no body. An upload
redirected that way comes back 200 with the object never written, and the step then
inventories a file that does not exist — which costs the whole delivery when
collection checks its hash.
"""
def redirect_request(self, req, fp, code, msg, headers, newurl):
raise urllib.error.HTTPError(
req.full_url, code, 'the storage endpoint redirected the request', headers, fp
)
class _StoppableHandler:
"""Substitute a stoppable connection for the one urllib was about to construct.
Intercepting ``do_open`` rather than ``http_open``/``https_open`` is what keeps this
scheme-agnostic: the plain-HTTP path is what a local demo and this repository's own
conformance suite exercise, and the TLS path is what every presigned URL in production
uses, so a fix that covered only the first would be invisible where it matters.
"""
def do_open(self, http_class, req, **kwargs):
return super().do_open(_stoppable_version_of(http_class), req, **kwargs)
class _StoppableHTTPHandler(_StoppableHandler, urllib.request.HTTPHandler):
pass
class _StoppableHTTPSHandler(_StoppableHandler, urllib.request.HTTPSHandler):
pass
_OPENER = urllib.request.build_opener(_NoRedirects, _StoppableHTTPHandler, _StoppableHTTPSHandler)
def _open(url: str, *, what: str):
"""GET one URL. Raises on a bad status, and never puts the URL in the message."""
request = urllib.request.Request(url, method='GET', headers={'User-Agent': USER_AGENT})
try:
response = _OPENER.open(request, timeout=READ_TIMEOUT_S)
except _Stopped:
raise # the connection refused to start because this run was called off
except urllib.error.HTTPError as exc:
raise _classify(exc, _http_error_detail(exc), f'reading {what}')
except urllib.error.URLError as exc:
raise TransientError(f'reading {what} failed: {redact(getattr(exc, "reason", exc))}')
except Exception as exc:
raise TransientError(f'reading {what} failed: {redact(exc)}')
status = int(getattr(response, 'status', 200) or 200)
if not 200 <= status < 300:
response.close()
raise TransientError(f'reading {what} returned HTTP {status}')
return response
class _MultipartBody:
"""A form body that streams: the fields, then the file, then the closing boundary.
``http.client`` reads an object with a ``read`` method in blocks, so the file never
exists in memory. That is the whole reason this class exists rather than a call to
a friendlier HTTP library — see the module docstring.
"""
def __init__(self, head: bytes, source_path: str, file_size: int, tail: bytes) -> None:
self._head = memoryview(head)
self._tail = memoryview(tail)
self._source_path = source_path
self._remaining = file_size
self._uncached = 0
self._handle = None
self._stage = 0 # 0 head, 1 file, 2 tail, 3 done
self._head_at = 0
self._tail_at = 0
self.length = len(head) + file_size + len(tail)
def __len__(self) -> int:
return self.length
def read(self, size: int = -1) -> bytes:
if size is None or size <= 0:
size = CHUNK_BYTES
while True:
if self._stage == 0:
if self._head_at < len(self._head):
piece = bytes(self._head[self._head_at:self._head_at + size])
self._head_at += len(piece)
return piece
self._stage = 1
self._handle = open(self._source_path, 'rb')
elif self._stage == 1:
# Never send more of the file than Content-Length promised: a body longer
# than its declared length desynchronises the connection rather than
# failing cleanly.
piece = self._handle.read(min(size, self._remaining))
if piece:
self._remaining -= len(piece)
self._uncached += len(piece)
if self._uncached >= CACHE_DROP_BYTES:
# Reading the file back fills the page cache just as writing it
# did, and that cache counts against the container's memory limit.
_release_page_cache(self._handle)
self._uncached = 0
return piece
self._handle.close()
self._handle = None
self._stage = 2
elif self._stage == 2:
if self._tail_at < len(self._tail):
piece = bytes(self._tail[self._tail_at:self._tail_at + size])
self._tail_at += len(piece)
return piece
self._stage = 3
else:
return b''
def close(self) -> None:
if self._handle is not None:
with contextlib.suppress(Exception):
self._handle.close()
self._handle = None
def _post_object(post: dict, key: str, source_path: str, size: int, what: str) -> None:
"""Upload one object through the presigned POST policy, streaming from disk.
``key`` is set explicitly rather than left to the ``${filename}`` placeholder: nested
relpaths then work predictably, and the policy's ``starts-with`` condition means the
store itself refuses anything outside this job's prefix.
"""
boundary = '----lspo' + hashlib.sha256(
f'{key}|{size}|{time.time()}'.encode('utf-8')).hexdigest()[:32]
dash = ('--' + boundary).encode('ascii')
head = io.BytesIO()
fields = dict(post.get('fields') or {})
fields['key'] = key
for name, value in fields.items():
head.write(dash + b'\r\n')
head.write(b'Content-Disposition: form-data; name="%s"\r\n\r\n'
% str(name).replace('"', '').encode('utf-8'))
head.write(str(value).encode('utf-8') + b'\r\n')
filename = os.path.basename(key).replace('"', '') or 'object'
head.write(dash + b'\r\n')
head.write(b'Content-Disposition: form-data; name="file"; filename="%s"\r\n'
% filename.encode('utf-8'))
head.write(b'Content-Type: application/octet-stream\r\n\r\n')
body = _MultipartBody(head.getvalue(), source_path, size, b'\r\n' + dash + b'--\r\n')
request = urllib.request.Request(
post['url'], data=body, method='POST',
headers={'Content-Type': 'multipart/form-data; boundary=' + boundary,
'Content-Length': str(len(body)),
'User-Agent': USER_AGENT},
)
try:
# ``closing`` releases the file handle the body streams from, on every path out.
# The transfer itself is abandoned through the CONNECTION, which is on the ledger
# from the moment its socket exists — before a byte of this body is sent.
with contextlib.closing(body):
response = _OPENER.open(request, timeout=UPLOAD_TIMEOUT_S)
except _Stopped:
raise # the connection refused to start because this run was called off
except urllib.error.HTTPError as exc:
raise _classify(exc, _http_error_detail(exc), f'the upload of {what}')
except urllib.error.URLError as exc:
# Ambiguous by nature: the store may already have accepted it. Never retried.
raise TransientError(
f'the upload of {what} failed before an answer arrived: '
f'{redact(getattr(exc, "reason", exc))}')
except Exception as exc:
raise TransientError(f'the upload of {what} failed before an answer arrived: {redact(exc)}')
with contextlib.closing(response):
status = int(getattr(response, 'status', 200) or 200)
if not 200 <= status < 300:
raise TransientError(f'the upload of {what} returned HTTP {status}')
# -------------------------------------------------------------- staging writes
#: Kept at module scope on purpose. Salvage publishes only what the MARKER inventories,
#: so an inventory local to the work function is empty on the failure path and everything
#: already uploaded is stranded in a staging area nobody will look at again.
INVENTORY: list[dict] = []
PORTS: dict[str, list[str]] = {}
#: Whether the store has actually ACCEPTED ``result.json``. Being in the inventory is not
#: the same claim: the ordinary write records the document before uploading it (see
#: :func:`publish` for why that order is right for work), so an upload that failed leaves a
#: record of an object nobody holds. The failure path reads this rather than the inventory,
#: because "already named" would tell it there is nothing left to do at exactly the moment
#: there is — and the marker would then send salvage after a file that is not there.
RESULT_UPLOADED = False
#: What this run has done so far, and the facts by which somebody will find it again.
#: Both are at module scope for the same reason the inventory is: the FAILURE path writes
#: a report document too, and a run that died on its third input still touched the first
#: two — which is exactly the run an operator goes looking for.
#:
#: **BEHAVIOUR.** The orchestrator reads the optional ``facts`` list out of ``result.json``
#: when it accepts this attempt's marker, whatever that marker says, and records each
#: entry against the execution. The run is then findable in the Runs search box by
#: ``input:data.csv`` — and by ``task:41`` or ``annotation:7`` for a node that records the
#: Label Studio ids it worked on, which is the convention worth following: record the ids
#: of the things you touched, not a description of what you did.
#:
#: **RECOMMENDATION.** Nothing requires any of this, and nothing punishes getting it
#: wrong: an entry that breaks a rule below is skipped by itself and the rest are still
#: recorded, with no effect on the run. What is said about it is one summary line in the
#: ORCHESTRATOR's log, counting how many were dropped — not one line per entry, and
#: nothing that reaches this container. The rules are the orchestrator's own
#: (``pipelines/facts.py``): each entry is an object with a ``key`` matching
#: ``^[a-z][a-z0-9_]{0,63}\Z``, a ``value`` that is a string or an integer — never a
#: boolean — non-blank, at most 512 characters and free of control characters, and an
#: optional ``meta``: a FLAT object of scalars (at most 32 keys, keys of 1 to 64
#: characters, each value one string, number, boolean or null — no nesting). Those rules
#: are exactly what its columns hold, so an entry it accepts can never be refused by the
#: store afterwards and take the document's other facts with it. At most 10,000 entries are
#: recorded (``external/contract.py`` ``MAX_RESULT_FACTS``), so a node with more things than
#: that to name should record something coarser rather than one fact per row.
#:
#: **RECOMMENDATION — apply those rules HERE, where they are still visible.** ``claim``
#: below does, and that is the part worth copying. A node that writes whatever it has and
#: lets the far side sort it out gets no error, no warning it will ever see and no fact:
#: the entry is dropped inside somebody else's worker log, and the only symptom is a run
#: that answers to nothing when it is searched for six weeks later. Checking at the point
#: of writing is what turns that into a sentence in this run's own report.
FACTS: list[dict] = []
METRICS: dict[str, int] = {'files': 0, 'total_bytes': 0, 'lines': 0}
#: Why the facts this run could not claim, counted rather than listed. The reason a fact
#: is unusable is the same reason for every one of its kind — one relpath scheme that runs
#: long, one job with more inputs than the cap — so a count and a cause say everything a
#: list would, in a bounded number of characters inside a document with a ceiling.
FACTS_UNCLAIMED: dict[str, int] = {'unusable': 0, 'bad_key': 0, 'over_cap': 0}
#: The orchestrator's own ingest limits for one fact, re-stated (``pipelines/facts.py``:
#: ``KEY_RE``, ``MAX_VALUE_LEN``, ``_CONTROL_RE``; ``external/contract.py``:
#: ``MAX_RESULT_FACTS``). ``\Z`` and not ``$``, exactly as the orchestrator writes it: ``$``
#: also matches immediately before a final newline, so a key written with one would pass a
#: check made with it and then be stored with the newline attached, where no search reaches
#: it. The surrogate range is in the control-character class for a harder reason than
#: searchability — half a UTF-16 surrogate pair has no UTF-8 encoding, so the row cannot be
#: stored at all. It gets into a value the ordinary way: a name copied off a filesystem
#: whose bytes are not valid UTF-8 is decoded with surrogate escapes.
_FACT_KEY = re.compile(r'^[a-z][a-z0-9_]{0,63}\Z')
MAX_FACT_VALUE_CHARS = 512
MAX_FACTS = 10_000
_CONTROL_IN_FACT = re.compile(r'[\x00-\x1f\x7f\ud800-\udfff]')
_BAD_IN_RELPATH = re.compile(r'[\x00-\x1f\\]')
def check_relpath(relpath: str) -> str:
"""The canonical-relpath rule, applied before writing rather than after.
The marker parser refuses anything else, and it refuses the whole document — so one
bad name costs every object in it.
"""
if not isinstance(relpath, str) or not relpath or relpath.startswith('/'):
raise StepError(f'output relpath {relpath!r} must be a non-empty relative path')
if _BAD_IN_RELPATH.search(relpath):
raise StepError(f'output relpath {relpath!r} carries a backslash or a control character')
if any(part in ('', '.', '..') for part in relpath.split('/')):
You can’t perform that action at this time.