Customizing CloudWatch Dashboard legend

Yes, it is possible to customize the legend on a CloudWatch dashboard to show only the Display Name of the EC2 instance. When editing a graph on your CloudWatch dashboard, you have options to modify how the legend appears.

To customize the legend to show only the Display Name:

1. Open the CloudWatch console and navigate to your dashboard.
2. Locate the graph you want to modify.
3. In the upper-right corner of the graph, click on "Widget actions".
4. From the dropdown menu, select "Edit".
5. In the graph editor, you can customize the metrics and their labels.
6. For each metric representing an EC2 instance, you can modify the label to show only the Display Name.

You can use dynamic labels to achieve this. Instead of showing the default information (Instance ID, Display Name, and Instance Type), you can set up the label to display only the tag or dimension you want - in this case, the Display Name.

Keep in mind that the exact steps might vary slightly depending on the specific widget type and the CloudWatch interface version you're using. However, the general principle of being able to customize metric labels and legends remains consistent across versions.

By customizing the legend in this way, you can make your CloudWatch dashboard more concise and easier to read, showing only the EC2 instance Display Names instead of the longer default format.
Sources
Editing a graph on a CloudWatch dashboard - Amazon CloudWatch