AWS Log Filtering: How to Fix FilterLogEvents Not Returning Events

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If you’re using the FilterLogEvents feature and getting an empty list of events, it can be frustrating. Here’s how you can troubleshoot and fix the issue so you can successfully retrieve your logs.

First, understand that sometimes the API call is still running and hasn’t finished searching all the log streams yet. If your response shows “completedLogStreamCount” as 0, but you know there are about 54 log streams to check, this means the request is still processing. You need to wait for it to complete or make sure you’re not hitting the limits too early.

Next, check if the response includes a nextToken. This token indicates there are more results waiting for you. To get all your logs, continue making requests using this nextToken. Keep fetching logs with the nextToken until you either retrieve all the events you need or receive a response without a nextToken, which means there are no more logs left to fetch.

It’s also helpful to narrow your search with time filters. Add startTime and endTime parameters to specify exactly when you want to search. Make sure to include these as Unix timestamps in milliseconds. This way, you’re not scanning all logs, only the ones relevant to your time frame.

If you’re looking for specific entries, such as errors, include a filterPattern in your request. This helps filter the logs so only the events matching your criteria are returned.

Here’s what a complete API request might look like:

json
{
“logGroupName”: ““,
“logStreamNamePrefix”: ““,
“startTime”: 1633046400000, // Example start timestamp
“endTime”: 1633132800000, // Example end timestamp
“filterPattern”: “ERROR” // Optional for specific content
}

For follow-up requests, make sure to include the nextToken from the previous response:

json
{
“logGroupName”: ““,
“logStreamNamePrefix”: ““,
“startTime”: 1633046400000,
“endTime”: 1633132800000,
“nextToken”: “”
}

If your logs are very large, consider focusing on specific log streams instead of filtering across many streams. This approach can help you handle logs more efficiently, especially when you know exactly where the relevant data resides.

Following these steps should help you fetch your logs successfully. If you need more details or run into other issues, there are helpful resources and documentation from AWS to guide you further.