Handling Webhook Delivery Failures with a Dead Letter Queue in Genesys Cloud

What You Will Build

• You will build a Python service that intercepts failed webhook deliveries from Genesys Cloud by polling the Webhook Delivery Log API.
• You will implement a retry mechanism that attempts to redeliver the payload to your endpoint, and a Dead Letter Queue (DLQ) pattern that persists permanently failed messages to a local JSON file for manual inspection.
• This tutorial uses the Genesys Cloud Python SDK (genesyscloud) and the requests library for HTTP operations.

Prerequisites

• OAuth Client: A Genesys Cloud OAuth client with the scope webhook:read and webhook:write (if you intend to update webhook status, though this tutorial focuses on reading logs and retrying).
• SDK Version: genesyscloud >= 13.0.0.
• Language/Runtime: Python 3.9+.
• Dependencies: Install the required packages via pip:

  pip install genesyscloud requests python-dotenv
  

• Environment: A .env file containing your Genesys Cloud credentials:

  GENESYS_CLOUD_REGION=us-east-1
  GENESYS_CLOUD_CLIENT_ID=your_client_id
  GENESYS_CLOUD_CLIENT_SECRET=your_client_secret
  WEBHOOK_ID=your_webhook_id
  

Authentication Setup

Genesys Cloud APIs require an OAuth 2.0 Bearer token. The Python SDK handles the token acquisition and refresh automatically when you initialize the PlatformClient. You must configure the client with your region, client ID, and client secret.

import os
from dotenv import load_dotenv
from genesyscloud.platform.client import PlatformClient
from genesyscloud.api.webhooks import WebhooksApi

# Load environment variables
load_dotenv()

def get_webhooks_api() -> WebhooksApi:
    """
    Initializes and returns the WebhooksApi instance with OAuth authentication.
    """
    platform_client = PlatformClient()
    
    # Configure OAuth credentials
    platform_client.set_environment(os.getenv("GENESYS_CLOUD_REGION"))
    platform_client.set_client_id(os.getenv("GENESYS_CLOUD_CLIENT_ID"))
    platform_client.set_client_secret(os.getenv("GENESYS_CLOUD_CLIENT_SECRET"))
    
    # Return the Webhooks API object
    return WebhooksApi(platform_client)

This setup ensures that every subsequent API call includes a valid Authorization: Bearer <token> header. The SDK caches the token and refreshes it silently before expiration, preventing 401 Unauthorized errors during long-running processes.

Implementation

Step 1: Polling for Failed Webhook Deliveries

Genesys Cloud maintains a delivery log for each webhook. When your endpoint returns a 5xx error, Genesys Cloud records the failure. You can query these failures using the get_webhook_deliveries endpoint.

The key parameter here is filter_status. You must set this to failed to retrieve only the deliveries that did not succeed. You should also specify a time window to avoid processing historical data indefinitely.

from datetime import datetime, timedelta
from genesyscloud.models import WebhookDeliveryQuery

def fetch_failed_deliveries(api: WebhooksApi, webhook_id: str, lookback_hours: int = 1) -> list:
    """
    Queries Genesys Cloud for failed webhook deliveries within the last N hours.
    
    Args:
        api: The initialized WebhooksApi instance.
        webhook_id: The UUID of the specific webhook.
        lookback_hours: How many hours back to search for failures.
        
    Returns:
        A list of WebhookDelivery objects that have failed.
    """
    now = datetime.utcnow()
    start_time = now - timedelta(hours=lookback_hours)
    
    # Format dates as ISO 8601 strings required by the API
    start_time_str = start_time.isoformat() + "Z"
    end_time_str = now.isoformat() + "Z"
    
    try:
        # Construct the query body
        # The 'filter_status' field is critical for filtering only failed attempts
        query_body = WebhookDeliveryQuery(
            filter_status="failed",
            start_date=start_time_str,
            end_date=end_time_str
        )
        
        # Call the API
        # Scope required: webhook:read
        response = api.get_webhook_deliveries(
            webhook_id=webhook_id,
            body=query_body
        )
        
        # The response contains a list of deliveries in the 'entities' field
        if response and response.entities:
            return response.entities
        else:
            return []
            
    except Exception as e:
        print(f"Error fetching deliveries: {e}")
        return []

Expected Response Structure:
The response.entities list contains objects with fields like:

• id: Unique ID for this specific delivery attempt.
• webhookId: The ID of the webhook.
• status: “failed”.
• httpStatusCode: The status code returned by your server (e.g., 500, 502, 503).
• body: The original JSON payload that Genesys Cloud tried to send.
• headers: The headers included in the request.

Step 2: Implementing the Retry Logic

When a delivery fails with a 5xx error, it is often transient (server overload, temporary network glitch). Your service should attempt to redeliver the payload. You will use the requests library to send the original payload to the original destination URL.

You must reconstruct the HTTP request using the data from the WebhookDelivery object. Note that Genesys Cloud includes the original headers in the delivery log. You should forward these headers (minus sensitive ones like Authorization if you are acting as a proxy, but typically you forward them to preserve the original context).

import requests
import time

def retry_delivery(delivery: object, max_retries: int = 3, delay_seconds: int = 5) -> bool:
    """
    Attempts to resend the webhook payload to the original URL.
    
    Args:
        delivery: The WebhookDelivery object containing payload and metadata.
        max_retries: Maximum number of retry attempts.
        delay_seconds: Seconds to wait between retries.
        
    Returns:
        True if the delivery succeeds, False otherwise.
    """
    # Extract necessary data from the delivery object
    target_url = delivery.webhook_url  # The URL the webhook is configured to hit
    payload = delivery.body            # The JSON body sent originally
    headers = delivery.headers or {}   # Original headers
    
    # Remove Genesys-specific headers that might confuse the target if they are not expected
    # Usually safe to keep Content-Type, etc.
    
    for attempt in range(1, max_retries + 1):
        try:
            print(f"Retry attempt {attempt}/{max_retries} for delivery ID: {delivery.id}")
            
            # Send the POST request
            # Use timeout to prevent hanging indefinitely
            response = requests.post(
                target_url,
                json=payload,  # Automatically serializes dict/list to JSON
                headers=headers,
                timeout=10
            )
            
            # Check if the response is successful (2xx)
            if response.status_code >= 200 and response.status_code < 300:
                print(f"Successfully redelivered delivery ID: {delivery.id} with status {response.status_code}")
                return True
            else:
                print(f"Retry failed with status code: {response.status_code}")
                # If it's still a 5xx, we might want to retry again
                # If it's a 4xx, it's likely a permanent error, so we should stop retrying
                if response.status_code >= 400 and response.status_code < 500:
                    print("Received 4xx error. Stopping retries.")
                    return False
                    
        except requests.exceptions.RequestException as e:
            print(f"Network error during retry: {e}")
            
        # Wait before next retry, unless it was the last attempt
        if attempt < max_retries:
            time.sleep(delay_seconds)
            
    return False

Step 3: Processing Results and the Dead Letter Queue

If the retry logic fails after all attempts, the message is considered “dead.” You must persist this data so it can be investigated later. This is the Dead Letter Queue (DLQ). For this tutorial, we will implement a simple file-based DLQ using JSON. In a production environment, you would write to Kafka, RabbitMQ, or an AWS SQS queue.

The DLQ entry must contain all context: the original payload, the error reason, the timestamp of failure, and the delivery ID.

import json
from datetime import datetime

def save_to_dlq(delivery: object, error_reason: str, dlq_file: str = "dlq.json"):
    """
    Saves a permanently failed delivery to a Dead Letter Queue file.
    
    Args:
        delivery: The WebhookDelivery object.
        error_reason: A string describing why the retries failed.
        dlq_file: The path to the JSON file acting as the DLQ.
    """
    dlq_entry = {
        "deliveryId": delivery.id,
        "webhookId": delivery.webhook_id,
        "timestamp": datetime.utcnow().isoformat() + "Z",
        "originalPayload": delivery.body,
        "originalHeaders": delivery.headers,
        "httpStatusCode": delivery.http_status_code,
        "errorReason": error_reason,
        "targetUrl": delivery.webhook_url
    }
    
    # Read existing DLQ entries
    existing_entries = []
    try:
        if os.path.exists(dlq_file):
            with open(dlq_file, 'r') as f:
                try:
                    existing_entries = json.load(f)
                except json.JSONDecodeError:
                    existing_entries = []
    except Exception as e:
        print(f"Error reading DLQ file: {e}")
        
    # Append new entry
    existing_entries.append(dlq_entry)
    
    # Write back to file
    try:
        with open(dlq_file, 'w') as f:
            json.dump(existing_entries, f, indent=2)
        print(f"Saved failed delivery {delivery.id} to DLQ.")
    except Exception as e:
        print(f"CRITICAL: Failed to write to DLQ: {e}")

Complete Working Example

The following script combines all steps into a single runnable module. It polls Genesys Cloud every 60 seconds for failed webhooks, attempts to retry them, and moves permanently failed ones to the DLQ.

import os
import time
import json
from datetime import datetime
from dotenv import load_dotenv
from genesyscloud.platform.client import PlatformClient
from genesyscloud.api.webhooks import WebhooksApi
from genesyscloud.models import WebhookDeliveryQuery
import requests

# Configuration
LOAD_ENV = True
POLL_INTERVAL_SECONDS = 60
LOOKBACK_HOURS = 1
MAX_RETRIES = 3
RETRY_DELAY_SECONDS = 5
DLQ_FILE = "dlq.json"

def get_webhooks_api():
    platform_client = PlatformClient()
    platform_client.set_environment(os.getenv("GENESYS_CLOUD_REGION"))
    platform_client.set_client_id(os.getenv("GENESYS_CLOUD_CLIENT_ID"))
    platform_client.set_client_secret(os.getenv("GENESYS_CLOUD_CLIENT_SECRET"))
    return WebhooksApi(platform_client)

def fetch_failed_deliveries(api, webhook_id, lookback_hours):
    now = datetime.utcnow()
    start_time = now - timedelta(hours=lookback_hours)
    start_time_str = start_time.isoformat() + "Z"
    end_time_str = now.isoformat() + "Z"
    
    query_body = WebhookDeliveryQuery(
        filter_status="failed",
        start_date=start_time_str,
        end_date=end_time_str
    )
    
    try:
        response = api.get_webhook_deliveries(
            webhook_id=webhook_id,
            body=query_body
        )
        if response and response.entities:
            return response.entities
        return []
    except Exception as e:
        print(f"Error fetching deliveries: {e}")
        return []

def retry_delivery(delivery, max_retries, delay_seconds):
    target_url = delivery.webhook_url
    payload = delivery.body
    headers = delivery.headers or {}
    
    for attempt in range(1, max_retries + 1):
        try:
            print(f"[{datetime.utcnow().isoformat()}] Retry attempt {attempt}/{max_retries} for ID: {delivery.id}")
            response = requests.post(
                target_url,
                json=payload,
                headers=headers,
                timeout=10
            )
            
            if 200 <= response.status_code < 300:
                print(f"[{datetime.utcnow().isoformat()}] Success! ID: {delivery.id}, Status: {response.status_code}")
                return True
            else:
                print(f"[{datetime.utcnow().isoformat()}] Failed retry. ID: {delivery.id}, Status: {response.status_code}")
                if 400 <= response.status_code < 500:
                    return False
        except requests.exceptions.RequestException as e:
            print(f"[{datetime.utcnow().isoformat()}] Network error: {e}")
            
        if attempt < max_retries:
            time.sleep(delay_seconds)
    return False

def save_to_dlq(delivery, error_reason, dlq_file):
    dlq_entry = {
        "deliveryId": delivery.id,
        "webhookId": delivery.webhook_id,
        "timestamp": datetime.utcnow().isoformat() + "Z",
        "originalPayload": delivery.body,
        "httpStatusCode": delivery.http_status_code,
        "errorReason": error_reason,
        "targetUrl": delivery.webhook_url
    }
    
    existing_entries = []
    if os.path.exists(dlq_file):
        try:
            with open(dlq_file, 'r') as f:
                existing_entries = json.load(f)
        except json.JSONDecodeError:
            existing_entries = []
            
    existing_entries.append(dlq_entry)
    
    with open(dlq_file, 'w') as f:
        json.dump(existing_entries, f, indent=2)

def main():
    if LOAD_ENV:
        load_dotenv()
        
    webhook_id = os.getenv("WEBHOOK_ID")
    if not webhook_id:
        raise ValueError("WEBHOOK_ID environment variable is required.")
        
    api = get_webhooks_api()
    
    print(f"Starting Webhook Retry Service for Webhook ID: {webhook_id}")
    print(f"Polling every {POLL_INTERVAL_SECONDS} seconds...")
    
    while True:
        try:
            # Step 1: Fetch failed deliveries
            failed_deliveries = fetch_failed_deliveries(api, webhook_id, LOOKBACK_HOURS)
            
            if not failed_deliveries:
                print("No failed deliveries found.")
            else:
                print(f"Found {len(failed_deliveries)} failed delivery(ies).")
                
            # Step 2 & 3: Process each failure
            for delivery in failed_deliveries:
                print(f"Processing delivery ID: {delivery.id}")
                
                # Attempt retry
                success = retry_delivery(delivery, MAX_RETRIES, RETRY_DELAY_SECONDS)
                
                if not success:
                    # Move to DLQ
                    save_to_dlq(
                        delivery, 
                        f"Failed after {MAX_RETRIES} retries", 
                        DLQ_FILE
                    )
                    
        except KeyboardInterrupt:
            print("Shutting down...")
            break
        except Exception as e:
            print(f"Unexpected error in main loop: {e}")
            
        # Wait before next poll
        time.sleep(POLL_INTERVAL_SECONDS)

if __name__ == "__main__":
    from datetime import timedelta
    main()

Common Errors & Debugging

Error: 403 Forbidden

Cause: The OAuth client used in the PlatformClient initialization lacks the webhook:read scope.

Fix:

1. Go to the Genesys Cloud Admin Portal.
2. Navigate to Admin > Security > OAuth Clients.
3. Select your client.
4. Ensure the scope webhook:read is checked.
5. Regenerate the client secret if you suspect the token was issued before the scope change.

Error: 429 Too Many Requests

Cause: You are polling the get_webhook_deliveries endpoint too frequently. Genesys Cloud enforces rate limits per client ID.

Fix:
Increase the POLL_INTERVAL_SECONDS in the configuration. The default of 60 seconds is usually safe. If you have a high volume of webhooks, consider implementing exponential backoff in the fetch_failed_deliveries function when a 429 is caught.

# Example rate limit handling in fetch_failed_deliveries
except Exception as e:
    if "429" in str(e):
        print("Rate limited. Waiting 10 seconds...")
        time.sleep(10)
        return []
    raise e

Error: Payload Mismatch on Retry

Cause: The delivery.body field in the Genesys Cloud log might be a stringified JSON string rather than a parsed dictionary, depending on the SDK version or how the webhook was configured.

Fix:
Before sending the retry request, ensure the payload is a valid JSON object.

import json

# Inside retry_delivery
if isinstance(payload, str):
    try:
        payload = json.loads(payload)
    except json.JSONDecodeError:
        # If it cannot be parsed, it might be a raw text payload
        # In this case, send as text, not JSON
        headers['Content-Type'] = 'text/plain'
        # Use requests.post(url, data=payload, headers=headers)

Error: DLQ File Locking

Cause: If multiple instances of this script run simultaneously, they will race to write to dlq.json, causing data corruption or PermissionError.

Fix:
For production, replace the file-based DLQ with a message queue (e.g., RabbitMQ, AWS SQS). If you must use a file, use a file lock library like fcntl (Linux/Mac) or msvcrt (Windows) to ensure atomic writes.

Official References

• Genesys Cloud Webhook Delivery Log API Documentation
• Genesys Cloud Python SDK Reference
• OAuth Scopes for Webhooks