Lab - Creating and Using Entity Selectors

What you will learn in this TP

• Confirm access to the Dynatrace cluster
• Generate an API Token with the correct permissions
• Understand the overall structure of an Entity Selector
• Master the basic selection criteria
• Write a complex Entity Selector
• Know how to target specific entities with tags
• Create an API Token with the necessary permissions
• Test an Entity Selector query via the REST API v2
• Dynamically validate the result returned by Dynatrace
• Create a Segment in the Dynatrace console
• Apply an Entity Selector rule to a segment

Prerequisites #

What you will learn in this section

• Confirm access to the Dynatrace cluster
• Generate an API Token with the correct permissions

You need a Dynatrace cluster (SaaS or Managed) with agents deployed, as well as an API Token with entity read permissions (`entities.read`).

Reminder: Syntax and Key Operators #

What you will learn in this section

• Understand the overall structure of an Entity Selector
• Master the basic selection criteria

An Entity Selector is a string used to filter Dynatrace entities. It's made up of selection criteria separated by commas (which act as a logical AND operator).

Tip: you can use the NOT operator to exclude entities, for example type("HOST"),not(tag("ENV:DEV")).

1. The main criteria

   Here are the most commonly used operators for targeting your entities:
   • type(): filters by entity type (e.g. HOST, SERVICE, APPLICATION).
   • tag(): filters by tag. Accepts the key:value format (e.g. tag("env:training")).
   • entityName(): filters by entity name, very useful with wildcard characters like *.

Creating an Entity Selector #

What you will learn in this section

• Write a complex Entity Selector
• Know how to target specific entities with tags

The goal is to isolate a subset of your infrastructure. Write an 'entity selector' that targets only the machines (HOST) with the tag 'env=training'.

Golden design rule (scaling): for every selection rule, you must always define either an Entity ID (the entity's unique identifier) or an Entity type.

Best practice: using fixed Entity IDs should be avoided in production, since they're too specific and rigid. To ensure management at scale that stays compatible with the dynamic lifecycle of your infrastructure, use only the Entity type combined with dynamic attributes or tags.

1. Selector syntax

   Write the query to select these entities.

2. Full Stack Linux servers

   List all Linux servers with 'Full stack' monitoring.

3. Tomcat and Docker services

   Display the services using the 'Apache Tomcat' and 'Docker' technologies.

Validation via API #

What you will learn in this section

• Create an API Token with the necessary permissions
• Test an Entity Selector query via the REST API v2
• Dynamically validate the result returned by Dynatrace

Before applying a rule to a Management Zone or a Segment, it's strongly recommended to test it. Use the Dynatrace API (v2) to check which entities are returned by your selector.

1. Creating the token

   To query the Dynatrace API, you need an API Token with the `entities.read` permission. Create this token in your Dynatrace environment.

2. Testing the queries

   Use the following `curl` commands to test the Entity Selectors you created. Don't forget to replace `{YOUR_TOKEN}` with your API token and to adapt your environment's URL if needed (here `https://demo.dynatrace.rousseltm.fr`).

   Tip: URL-encoding special characters (like quotes `"`, which become `%22`) is crucial for `curl` requests.

Creating segments #

What you will learn in this section

• Create a Segment in the Dynatrace console
• Apply an Entity Selector rule to a segment

Now that your 'entity selector' is validated, use it to create a new segment named after your first name.

1. Configuration in the console

   Describe the steps to create the Segment based on the 'Tomcat and Docker services' selector in the Dynatrace interface.

Difficulty level : ●●●○○ (3/5)