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Obtain and cache a ServiceNow OAuth2 access token

by
Published Apr 19, 2026

Authenticates against a ServiceNow instance using OAuth2 ROPC flow. The token is cached in a Windmill state resource (f/ServiceNow/snow_token_cache) and reused until it is within 60 seconds of expiry (default token lifetime is 30 minutes), minimising redundant auth calls across scripts in the same workspace. Run standalone to verify credentials and warm the cache, or import get_token as a shared auth helper in other ServiceNow scripts. Inputs: snow — ServiceNow resource (instance_url, client_id, client_secret, username, password)

Script servicenow
  • Submitted by elib3n379 Python3
    Created 51 days ago
    All edits
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    import time
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    import requests
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    from typing import TypedDict
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    try:
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        import wmill
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        _WMILL_AVAILABLE = True
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    except ImportError:
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        _WMILL_AVAILABLE = False
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    TOKEN_CACHE_PATH = "f/ServiceNow/snow_token_cache"
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    TOKEN_EXPIRY_BUFFER_SECS = 60
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    class servicenow(TypedDict):
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        instance_url: str
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        client_id: str
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        client_secret: str
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        username: str
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        password: str
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    def get_token(snow: servicenow) -> str:
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        """
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        Returns a valid ServiceNow access token.
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        Caches the token in f/ServiceNow/snow_token_cache and reuses it until
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        it is within 60s of expiry (default lifetime is 30 minutes).
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        Uses OAuth2 Resource Owner Password Credentials grant.
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        """
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        if _WMILL_AVAILABLE:
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            try:
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                cached = wmill.get_resource(TOKEN_CACHE_PATH)
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                if (
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                    isinstance(cached, dict)
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                    and cached.get("expires_at", 0) > time.time() + TOKEN_EXPIRY_BUFFER_SECS
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                ):
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                    return cached["token"]
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            except Exception:
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                pass
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        resp = requests.post(
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            f"{snow['instance_url'].rstrip('/')}/oauth_token.do",
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            data={
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                "grant_type": "password",
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                "client_id": snow["client_id"],
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                "client_secret": snow["client_secret"],
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                "username": snow["username"],
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                "password": snow["password"],
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            },
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            headers={"Content-Type": "application/x-www-form-urlencoded"},
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            timeout=15,
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        )
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        resp.raise_for_status()
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        data = resp.json()
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        if "error" in data:
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            raise RuntimeError(f"ServiceNow OAuth error: {data['error']} — {data.get('error_description', '')}")
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        token = data["access_token"]
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        expires_in = data.get("expires_in", 1800)
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        if _WMILL_AVAILABLE:
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            try:
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                wmill.set_resource(
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                    path=TOKEN_CACHE_PATH,
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                    value={"token": token, "expires_at": time.time() + expires_in},
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                    resource_type="state",
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                )
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            except Exception:
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                pass
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        return token
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    def main(snow: servicenow) -> str:
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        """Verify credentials and warm the token cache. Safe to run standalone."""
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        token = get_token(snow)
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        print(f"Token obtained successfully (prefix: {token[:10]}...)")
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        print(f"Cached at: {TOKEN_CACHE_PATH}")
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        return "OK"
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