Component templates in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of creating a component template with settings

What is the output of this Elasticsearch API call when creating a component template named my_template with a number_of_shards setting of 3?

Elasticsearch

PUT _component_template/my_template
{
  "template": {
    "settings": {
      "number_of_shards": 3
    }
  }
}

A {"acknowledged":true}

B {"error":"component_template_already_exists_exception"}

C {"acknowledged":false}

D {"error":"invalid_template_settings"}

💡 Hint

Creating a new component template returns an acknowledged true response if successful.

When you create a component template successfully, Elasticsearch responds with {"acknowledged":true}. Errors occur if the template exists or settings are invalid.

❓ Predict Output

intermediate

Result of applying a component template to an index template

Given a component template comp_temp that sets number_of_replicas to 2, what will be the number_of_replicas setting of an index created from an index template that uses this component template?

Elasticsearch

PUT _component_template/comp_temp
{
  "template": {
    "settings": {
      "number_of_replicas": 2
    }
  }
}

PUT _index_template/my_index_template
{
  "index_patterns": ["myindex*"],
  "composed_of": ["comp_temp"]
}

PUT myindex1

A 0

B 1

C Undefined (error)

D 2

💡 Hint

Component templates settings are merged into index templates and applied to indices.

The component template sets number_of_replicas to 2, so the index created from the index template that uses it will have number_of_replicas = 2.

🔧 Debug

advanced

Identify the error in this component template definition

What error will this component template creation request produce?

Elasticsearch

PUT _component_template/bad_template
{
  "template": {
    "mappings": {
      "properties": {
        "name": { "type": "text" },
        "age": { "type": "integer" }
      }
    },
    "settings": {
      "number_of_shards": "two"
    }
  }
}

A No error, template created successfully

B ValidationException: number_of_shards must be an integer

C ParsingException: unknown field 'mappings' in template

D ElasticsearchTimeoutException

💡 Hint

Check the type of the number_of_shards setting value.

The number_of_shards setting must be an integer, but here it is a string "two", causing a validation error.

🧠 Conceptual

advanced

Understanding component template composition order

If an index template composes two component templates, compA and compB, and both define the refresh_interval setting differently, which value will the index use?

A The value from the index template itself, ignoring component templates

B The value from the first component template listed in the composed_of array

C The value from the last component template listed in the composed_of array

D Elasticsearch throws a conflict error and refuses to create the index

💡 Hint

Later component templates override earlier ones in the composition order.

When multiple component templates define the same setting, the last one in the composed_of list overrides earlier ones.

❓ Predict Output

expert

Output of retrieving a non-existent component template

What is the output of this request when the component template missing_template does not exist?

Elasticsearch

GET _component_template/missing_template

A {"error":{"root_cause":[{"type":"resource_not_found_exception","reason":"component_template [missing_template] missing"}],"type":"resource_not_found_exception","reason":"component_template [missing_template] missing"},"status":404}

B {"component_templates":[]}

C {"acknowledged":false}

D {"error":"index_not_found_exception"}

💡 Hint

Elasticsearch returns a 404 error with details if the component template is missing.

Requesting a non-existent component template returns a 404 resource_not_found_exception error with a descriptive message.