LANGCHAIN_TRACING_V2 与 LANGSMITH_TRACING：新旧变量并存时谁生效

langchain-core 1.7.0 | langsmith 0.14.12

[1] tracing switch
case                                                          enabled  tracer
(nothing set)                                                 False    off
LANGSMITH_TRACING=true                                        True     on
LANGCHAIN_TRACING_V2=true                                     True     on
LANGSMITH_TRACING=false + LANGCHAIN_TRACING_V2=true           True     on
LANGSMITH_TRACING=true + LANGCHAIN_TRACING_V2=false           False    off
LANGSMITH_TRACING=True                                        False    off
LANGSMITH_TRACING=1                                           False    off
LANGCHAIN_TRACING_V2=true + tracing_context(enabled=False)    False    off
LANGCHAIN_TRACING_V2=true + ls.configure(enabled=False)       False    off

[2] project, key and endpoint
case                                                                                    value
LANGCHAIN_PROJECT=old-proj                                                              old-proj
LANGSMITH_PROJECT=new-proj + LANGCHAIN_PROJECT=old-proj                                 new-proj
LANGCHAIN_API_KEY=key-old                                                               key-old
LANGSMITH_API_KEY=key-new + LANGCHAIN_API_KEY=key-old                                   key-new
LANGCHAIN_ENDPOINT=http://localhost:9/old                                               http://localhost:9/old
LANGSMITH_ENDPOINT=http://localhost:9/new + LANGCHAIN_ENDPOINT=http://localhost:9/old   http://localhost:9/new

# langsmith/utils.py (0.14.12), last step of tracing_is_enabled()
var_result = get_env_var("TRACING_V2", default=get_env_var("TRACING", default=""))
return var_result == "true"

"""Report whether tracing is on in this process and which variable names are set.
 
Run it in the same shell, virtual environment or container as the failing process. To reproduce a
leftover variable without touching your shell, pass NAME=VALUE pairs: they are applied before
langsmith is imported.
"""
import os
import sys
 
for pair in sys.argv[1:]:
    name, _, value = pair.partition("=")
    os.environ[name] = value
 
from langsmith.utils import tracing_is_enabled  # noqa: E402  (must run after the variables are applied)
 
for name in ("LANGSMITH_TRACING", "LANGCHAIN_TRACING_V2", "LANGSMITH_TRACING_V2", "LANGCHAIN_TRACING"):
    print(f"{name:<22}{os.environ.get(name, '(unset)')!r}")
print("tracing_is_enabled():", tracing_is_enabled())

LANGSMITH_TRACING     'false'
LANGCHAIN_TRACING_V2  'true'
LANGSMITH_TRACING_V2  '(unset)'
LANGCHAIN_TRACING     '(unset)'
tracing_is_enabled(): True

"""Which LangSmith environment variable wins when old (LANGCHAIN_*) and new (LANGSMITH_*) names are both set?
 
Every case runs in a fresh child process with a clean environment, because langsmith caches some
environment lookups. The child only asks the libraries what they would do: it never starts a run
and never touches the network.
"""
import json
import os
import subprocess
import sys
from importlib.metadata import version
 
CHILD = r'''
import json
import sys
import warnings
 
warnings.simplefilter("ignore")
 
import langsmith as ls
from langchain_core.callbacks.manager import CallbackManager
from langsmith import utils
 
 
def snapshot():
    handlers = [type(h).__name__ for h in CallbackManager.configure().handlers]
    return {
        "tracing": utils.tracing_is_enabled(),
        "tracer": "LangChainTracer" in handlers,
        "project": utils.get_tracer_project(),
        "api_key": utils.get_api_key(None),
        "api_url": utils.get_api_url(None),
    }
 
 
mode = sys.argv[1]
if mode == "context_off":
    with ls.tracing_context(enabled=False):
        result = snapshot()
elif mode == "configure_off":
    ls.configure(enabled=False)
    result = snapshot()
else:
    result = snapshot()
print(json.dumps(result))
'''
 
# (label, environment variables, how the code overrides them)
SWITCH_CASES = [
    ("(nothing set)", {}, "env"),
    ("LANGSMITH_TRACING=true", {"LANGSMITH_TRACING": "true"}, "env"),
    ("LANGCHAIN_TRACING_V2=true", {"LANGCHAIN_TRACING_V2": "true"}, "env"),
    ("LANGSMITH_TRACING=false + LANGCHAIN_TRACING_V2=true", {"LANGSMITH_TRACING": "false", "LANGCHAIN_TRACING_V2": "true"}, "env"),
    ("LANGSMITH_TRACING=true + LANGCHAIN_TRACING_V2=false", {"LANGSMITH_TRACING": "true", "LANGCHAIN_TRACING_V2": "false"}, "env"),
    ("LANGSMITH_TRACING=True", {"LANGSMITH_TRACING": "True"}, "env"),
    ("LANGSMITH_TRACING=1", {"LANGSMITH_TRACING": "1"}, "env"),
    ("LANGCHAIN_TRACING_V2=true + tracing_context(enabled=False)", {"LANGCHAIN_TRACING_V2": "true"}, "context_off"),
    ("LANGCHAIN_TRACING_V2=true + ls.configure(enabled=False)", {"LANGCHAIN_TRACING_V2": "true"}, "configure_off"),
]
 
# (label, environment variables, snapshot field that the case is about)
SETTING_CASES = [
    ("LANGCHAIN_PROJECT=old-proj", {"LANGCHAIN_PROJECT": "old-proj"}, "project"),
    ("LANGSMITH_PROJECT=new-proj + LANGCHAIN_PROJECT=old-proj", {"LANGSMITH_PROJECT": "new-proj", "LANGCHAIN_PROJECT": "old-proj"}, "project"),
    ("LANGCHAIN_API_KEY=key-old", {"LANGCHAIN_API_KEY": "key-old"}, "api_key"),
    ("LANGSMITH_API_KEY=key-new + LANGCHAIN_API_KEY=key-old", {"LANGSMITH_API_KEY": "key-new", "LANGCHAIN_API_KEY": "key-old"}, "api_key"),
    ("LANGCHAIN_ENDPOINT=http://localhost:9/old", {"LANGCHAIN_ENDPOINT": "http://localhost:9/old"}, "api_url"),
    (
        "LANGSMITH_ENDPOINT=http://localhost:9/new + LANGCHAIN_ENDPOINT=http://localhost:9/old",
        {"LANGSMITH_ENDPOINT": "http://localhost:9/new", "LANGCHAIN_ENDPOINT": "http://localhost:9/old"},
        "api_url",
    ),
]
 
 
def run_case(extra: dict, mode: str) -> dict:
    """Run one case in a child process whose LangSmith variables are exactly `extra`."""
    env = {k: v for k, v in os.environ.items() if not k.startswith(("LANGSMITH_", "LANGCHAIN_"))}
    env.update(extra)
    proc = subprocess.run([sys.executable, "-c", CHILD, mode], env=env, capture_output=True, text=True, timeout=60)
    if proc.returncode != 0:
        raise SystemExit(f"child failed for {extra}: {proc.stderr[-400:]}")
    return json.loads(proc.stdout.strip().splitlines()[-1])
 
 
def main() -> None:
    print(f"langchain-core {version('langchain-core')} | langsmith {version('langsmith')}")
    print()
    print("[1] tracing switch")
    print(f"{'case':<62}{'enabled':<9}tracer")
    for label, extra, mode in SWITCH_CASES:
        got = run_case(extra, mode)
        print(f"{label:<62}{got['tracing']!s:<9}{'on' if got['tracer'] else 'off'}")
    print()
    print("[2] project, key and endpoint")
    print(f"{'case':<88}value")
    for label, extra, field in SETTING_CASES:
        print(f"{label:<88}{run_case(extra, 'env')[field]}")
 
 
if __name__ == "__main__":
    main()