# AWS Elemental MediaTailor ADS log analysis in Amazon CloudWatch Logs Insights
<a name="monitor-cloudwatch-ads-logs"></a>

You can view and query AWS Elemental MediaTailor ad decision server (ADS) logs using Amazon CloudWatch Logs Insights. MediaTailor sends event logs to CloudWatch for normal processing and error conditions. The logs adhere to a JSON schema. Through CloudWatch Logs Insights, you can select logs by time frame, and then run queries against them. 

For general information, see [Analyze log data with CloudWatch Logs insights](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/AnalyzingLogData.html). 

**Note**  
To access the logs, you need permissions to access Amazon CloudWatch. For instructions, see [Permissions for Amazon CloudWatch Logs](monitoring-permissions.md). 

**To view and query ADS logs using the CloudWatch console**

1. Open the CloudWatch console at [https://console.aws.amazon.com/cloudwatch/](https://console.aws.amazon.com/cloudwatch/).

1. In the navigation pane, under **Logs**, choose **Insights**.

1. In the search bar, enter **AdDec**, and then from the drop-down list, select `MediaTailor/AdDecisionServerInteractions`.

1. (Optional) Adjust the time period that you want to study. 

1. (Optional) Change the query in the dialog box. For general guidance, see [CloudWatch Logs insights query syntax](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/CWL_QuerySyntax.html). For examples of queries for MediaTailor ADS, see [Querying the ADS logs](querying-the-ads-logs.md).

1. Choose **Run query**. The query might take a few seconds, during which time **Cancel** appears in place of **Run query**. 

1. (Optional) To export the results as a CSV file, choose **Actions**, and then choose **Download query results (CSV)**. 

**Note**  
The console limits the number of records that it returns in query results and that it exports, so for bulk data, use the API, the AWS Command Line Interface (AWS CLI), or an SDK.

**Topics**
+ [Querying the ADS logs](querying-the-ads-logs.md)

# Querying the ADS logs
<a name="querying-the-ads-logs"></a>

CloudWatch Logs Insights provides a rich set of options for querying your logs. For detailed information about querying syntax, see [CloudWatch Logs insights query syntax](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/CWL_QuerySyntax.html). This section provides examples of common queries to get you started with your ADS logs queries. All queries run against the logs for the current time range setting.

The following query retrieves all information from the ADS logs. 

```
fields @timestamp, eventType, sessionId, requestId, @message
| sort sessionId, @timestamp asc
```

The following query retrieves all requests to the ADS. This query shows a way to retrieve the request header contents for MediaTailor logs. 

```
fields @timestamp, adsRequestUrl, requestHeaders.0.value as @userAgent, requestHeaders.1.value as @xForwardedFor, sessionId, requestId
| filter eventType = "MAKING_ADS_REQUEST"
| sort @timestamp asc
```

The following query retrieves the ads MediaTailor inserted for a given session.

```
fields @timestamp, sessionId, requestId, @message
| filter eventType = "FILLED_AVAIL"
| sort @timestamp asc
```

The following query retrieves the tracking URLs that MediaTailor called on behalf of the player.

```
fields @timestamp, beaconInfo.trackingEvent, beaconInfo.beaconUri, beaconInfo.headers.0.value as @userAgent, beaconInfo.headers.1.value as @xForwardedFor, sessionId, requestId
| filter eventType = "BEACON_FIRED"
| sort @timestamp asc
```

The following query retrieves information for a specific playback session, by filtering the results by `sessionId`. 

```
fields @timestamp, eventType, sessionId, requestId, @message
| filter sessionId = "0aaf6507-c6f9-4884-bfe7-f2f841cb8195"
| sort @timestamp asc
```

The following query retrieves information for a single request, by filtering the results by `requestId`.

```
fields @timestamp, eventType, sessionId, requestId, @message
| filter requestId = "f5d3cf39-6258-4cf1-b3f6-a34ff8bf641d"
| sort @timestamp asc
```

The following query retrieves a count of log entries for each event type that was logged.

```
fields eventType
| stats count() as @eventCount by eventType
```

The following query retrieves the avail ID and list of skipped ads for all avails that had skipped ads.

```
fields avail.availId
| parse @message '"skippedAds":[*]' as @skippedAdsList
| filter ispresent(@skippedAdsList)
```