Index templates in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this index template creation?

Given this Elasticsearch index template creation command, what will be the number of shards for any new index matching the pattern?

Elasticsearch

{
  "index_patterns": ["logs-*"],
  "template": {
    "settings": {
      "number_of_shards": 3,
      "number_of_replicas": 1
    }
  }
}

A New indices matching 'logs-*' will have 1 shard and 3 replicas.

B New indices matching 'logs-*' will have 3 shards and 1 replica.

C New indices matching 'logs-*' will have default shards and replicas because the template is invalid.

D New indices matching 'logs-*' will have 3 shards but 0 replicas.

💡 Hint

Look at the settings inside the template for shards and replicas.

The template explicitly sets number_of_shards to 3 and number_of_replicas to 1, so any new index matching 'logs-*' will inherit these settings.

🧠 Conceptual

intermediate

What is the main purpose of an index template in Elasticsearch?

Choose the best description of what an index template does.

A It monitors cluster health and sends alerts.

B It deletes old indices based on age.

C It automatically applies settings and mappings to new indices matching a pattern.

D It backs up existing indices to a remote location.

💡 Hint

Think about how you can prepare new indices before they are created.

Index templates define settings and mappings that automatically apply to new indices matching specified patterns.

📝 Syntax

advanced

Which option correctly defines an index template with a priority of 10?

Select the valid JSON snippet that sets an index template with priority 10.

A { "index_patterns": ["app-*"], "priority": 10, "template": { "settings": { "number_of_shards": 2 } } }

B { "index_patterns": ["app-*"], "template": { "priority": 10, "settings": { "number_of_shards": 2 } } }

C { "priority": 10, "index_patterns": ["app-*"], "settings": { "number_of_shards": 2 } }

D { "index_patterns": ["app-*"], "template": { "settings": { "number_of_shards": 2 } }, "priority": "ten" }

💡 Hint

Priority is a top-level field, not inside template.

Priority must be a top-level field with a numeric value. Option A correctly places priority at the top level with a number 10.

❓ optimization

advanced

How can you optimize index templates to reduce duplication when multiple templates share settings?

Which approach best reduces duplication across multiple index templates?

A Copy and paste the same settings into each index template.

B Avoid using templates and set settings manually per index.

C Create one large index template that matches all patterns.

D Use component templates and compose them in index templates.

💡 Hint

Think about reusable building blocks in Elasticsearch templates.

Component templates allow reusable settings and mappings that can be composed into multiple index templates, reducing duplication.

🔧 Debug

expert

Why does this index template fail to apply settings to new indices?

Given this template JSON, why won't new indices matching 'data-*' get the custom analyzer? { "index_patterns": ["data-*"], "settings": { "analysis": { "analyzer": { "custom_lowercase": { "type": "custom", "tokenizer": "standard", "filter": ["lowercase"] } } } } }

A The 'settings' block must be inside a 'template' object, not at the top level.

B The analyzer name 'custom_lowercase' is invalid and must be 'lowercase_custom'.

C Index patterns must be a string, not an array.

D The 'filter' field should be 'filters' in the analyzer definition.

💡 Hint

Check the required structure of an index template JSON.

In Elasticsearch index templates, the 'settings' must be nested inside a 'template' object. Placing 'settings' at the top level causes the template to be ignored.