Retry safely · Docs

Networks fail. If a submit times out, you can't tell whether the job was queued. The fix is to create the Idempotency-Key once per job and send the same key on every retry: if the first attempt went through, the retry returns its result instead of queuing a second job. Idempotency has the rules.

Plain HTTP (Python with httpx)

import os
import random
import time
import uuid
 
import httpx
 
API = "https://api.cognichem.com/api/v1"
HEADERS = {"X-Api-Key": os.environ["COGNICHEM_API_KEY"]}
RETRY = {"upstream", "timeout", "quota"}
 
 
def submit(job, attempts=5):
    key = str(uuid.uuid4())  # one key for this job, reused on every retry
    for attempt in range(attempts):
        try:
            response = httpx.post(
                f"{API}/jobs/submit",
                json=job,
                headers={**HEADERS, "Idempotency-Key": key},
                timeout=30,
            )
        except httpx.TransportError:
            pass  # no response: safe to retry with the same key
        else:
            if response.status_code < 400:
                return response.json()["process_id"]
            problem = response.json()
            if response.status_code != 409 and problem.get("retryability") not in RETRY:
                raise RuntimeError(f"{problem['status']} {problem.get('detail')}")
            # 409: the first attempt is still in progress; wait and retry the same key.
        time.sleep(min(30, 2**attempt) + random.random())
    raise RuntimeError("gave up after retries")

With the Python SDK

The SDK sends a new key on every call, so for a retry loop pass your own:

import uuid
 
from cognichem_client import CogniChem
from cognichem_client.errors import CogniChemError
 
client = CogniChem.from_env()
key = str(uuid.uuid4())
 
for attempt in range(5):
    try:
        job = client.jobs.submit(
            job_name="padel-batch-7",
            job_type="padel-descriptor",
            payload={"input_data": ["CCO"], "input_format": "smiles"},
            idempotency_key=key,
        )
        break
    except CogniChemError as error:
        if error.retryability not in {"upstream", "timeout", "quota"}:
            raise

Don'ts

Don't build the key from the payload: two jobs you mean to run separately would collide, and the second would quietly return the first.
Don't reuse a key with a changed body. That returns 409, not a second job.
Don't retry validation or auth errors unchanged; fix the request first (Handling errors).