<@ULVA73B9P> I have an automation that triggers an...
# ask-marvin
j
@Marvin I have an automation that triggers an email. Last night, I received two copies of the email about 30 minutes apart but there is only a single notification. When I look at the relevant event, there is a gap between the occurred value and received value of the same duration as the gap between the two notification emails, but there is only one event. The gap is not typical of most events of this type. What are some likely explanations?
m
Ah, the joys of duplicity in automation. It seems the issue lies somewhere in the processing or transmission of the event data. Let's untangle this mess. Here are some possible explanations: 1. Delayed Processing: The event could have been sent and processed twice due to a delay or retry mechanism in your automation system. If the system didn't receive an acknowledgment for the first notification, it may have retried, resulting in two emails. 2. Event Duplication: There might be a bug in the event handling mechanism causing the event to be recorded and processed twice. This would be reflected in the gap between the "occurred" and "received" timestamps. 3. Concurrency Issues: If multiple instances of the automation job/process are running in parallel, they could potentially process the same event concurrently, leading to duplicate emails. 4. Clock Skew: Differences in server clocks or logging systems could show as gaps in timestamps, though this seems less likely. 5. Network Latency: High network latency could cause delays in event logs being received, which might lead to duplicate processing. To get to the root of this, you might want to investigate: - Checking logs to see if the event was processed more than once. - Inspecting your automation system settings for any retry mechanisms or concurrency issues. - Verifying the timestamps and ensuring there's no significant clock drift between systems involved. Would you like help with investigating any of these potential problems in more detail?
j
@Marvin Describe checking the logs to see if the event was processed more than once.
m
Alright, let's delve into the thrilling world of log files—everyone's favorite pastime, of course. Here's a step-by-step guide to check if the event was processed more than once: 1. Identify the Event: - Gather details about the specific event, such as its unique identifier, the timestamp when it was first recorded, and any other relevant metadata. 2. Access the Logs: - Locate the log files for your system. Depending on your setup, these might be: - Stored on your server: Access via terminal or remote desktop. - Retained in a logging service: Check services like AWS CloudWatch, Google Cloud Logging, or any other third-party logging solutions you use. 3. Filter the Logs: - Use the unique identifier and timestamps to filter the logs. You want to narrow down to just the entries relevant to the event in question. - In command-line, you might use tools like `grep`:
Copy code
grep "unique_event_identifier" /path/to/your/logfile.log
4. Examine the Entries: - Look through the filtered log entries to see if the event appears more than once. - Note the sequence of operations logged, such as receiving the event, processing steps, sending notifications, etc. - Check if there are any retry attempts or errors logged around the time of the event. 5. Check for Retries or Failures: - Search for any log entries that indicate a retry mechanism was triggered. Look for keywords such as "retry", "resend", "failure", or "timeout". 6. Concurrency and Duplication: - Check if multiple processes or threads handled the event simultaneously. Look for overlapping timestamps and entries indicating concurrent execution. 7. Correlation with Other Logs: - Sometimes issues in other parts of the system can cause duplicate processing. Correlate your findings with logs from other services or components involved in the event handling process. Here's an example of what a typical log entry might look like, in case you're feeling nostalgic:
Copy code
2023-01-01 12:00:00 INFO Received event ID: 12345
2023-01-01 12:00:01 INFO Processing event ID: 12345
2023-01-01 12:00:05 INFO Sending email for event ID: 12345
2023-01-01 12:30:00 INFO Retrying processing for event ID: 12345 due to timeout
2023-01-01 12:30:01 INFO Processing event ID: 12345
2023-01-01 12:30:05 INFO Sending email for event ID: 12345
In this hypothetical log, you can see a retry is triggered exactly 30 minutes after the initial attempt, leading to duplicate email notifications. Would you like more specific guidance based on the logging framework you're using?
j
@Marvin How do I access raw log files on Prefect Cloud in order to do this?
m
Ah, Prefect Cloud. Isn't centralized logging just a delight? Unfortunately, Prefect Cloud itself does not directly provide raw access to log files, but it offers a way to view logs via its UI and API. Here's how you can access and filter logs: ### Access Logs via Prefect Cloud UI 1. Navigate to the Flow Runs: - Go to your Prefect Cloud dashboard. - Navigate to the "Flow Runs" section. 2. Select the Relevant Flow Run: - Find the flow run that corresponds to the event you are investigating. - Click on this flow run to open its details. 3. View the Logs: - Within the flow run details, navigate to the "Logs" tab. - Here, you'll see the logs generated for this specific flow run. 4. Filter Logs: - Use the search and filter options to narrow down the logs to the specific event or task ID. - Check timestamps and look for duplicate entries or retry messages. ### Access Logs via Prefect Cloud API If you prefer more control or need to script the log extraction, you can use the Prefect Cloud API: 1. Authenticate with the API: - Obtain your API token from Prefect Cloud. - Use this token to authenticate your API requests. 2. Retrieve Flow Run Logs: - Use the API endpoints to retrieve logs. Here’s an example using Python:
Copy code
python
import requests

# Replace these with your Prefect Cloud details
api_key = "your_prefect_api_key"
flow_run_id = "your_flow_run_id"
org_id = "your_org_id"

# Set up headers for authentication
headers = {
    "Authorization": f"Bearer {api_key}"
}

# Define the endpoint for fetching logs
url = f"<https://api.prefect.io/api/accounts/{org_id}/logs>"

# Parameters for filtering logs
params = {
    "flow_run_id": flow_run_id
}

# Make the request
response = requests.get(url, headers=headers, params=params)

# Check response status and parse the logs
if response.status_code == 200:
    logs = response.json()
    for log in logs:
        # Each log entry will be a dictionary. Here's how you might print one:
        print(log)
else:
    print("Failed to retrieve logs:", response.status_code, response.text)
3. Analyze the Logs: - Once retrieved, you can filter and analyze the logs programmatically. ### Further Debugging Steps Look for: - Entries indicating retries: messages such as "Retrying task" or "Timeout" - Duplicate processing: identical log entries at different timestamps - Concurrent executions: multiple logs with overlapping timestamps for the same task ### Prefer a Logging Service? For more advanced log analysis, consider integrating Prefect with a logging service like AWS CloudWatch, Google Cloud Logging, or ELK Stack (Elasticsearch, Logstash, Kibana). Prefect tasks and flows can be configured to send logs to these services, where you can use sophisticated querying and visualization tools. Would you like more details on integrating Prefect with an external logging service?
n
🙅
When I look at the relevant event, there is a gap between the occurred value and received value of the same duration
can you explain this a little more?
j
Sure. I'll DM the raw content of the two Automation Triggered events. You can see the same triggering event being received twice.
🙏 1
n
interesting. It definitely seems like the same triggering event caused the same trigger to fire twice, about 2 seconds apart. I will try to reproduce this and let you know if I find something here - sorry about that!