Installation and setup in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Elasticsearch service status check

After installing Elasticsearch on a Linux system, you run the command systemctl status elasticsearch. What output indicates that Elasticsearch is running correctly?

A Failed to start elasticsearch.service: Unit elasticsearch.service not found.

B Active: inactive (dead) since Mon 2024-06-10 10:00:00 UTC; 5min ago

C Active: active (running) since Mon 2024-06-10 10:00:00 UTC; 5min ago

D Active: activating (start) since Mon 2024-06-10 10:00:00 UTC; 5min ago

💡 Hint

Look for the word 'active' and 'running' in the status output.

The status output shows 'active (running)' when Elasticsearch is successfully running as a service.

🧠 Conceptual

intermediate

Default Elasticsearch port

What is the default port number Elasticsearch listens on for HTTP requests after installation?

A 9200

B 9300

C 8080

D 5601

💡 Hint

This port is used to send REST API requests to Elasticsearch.

Elasticsearch listens on port 9200 by default for HTTP REST API calls.

🔧 Debug

advanced

Elasticsearch JVM memory setting error

You set ES_JAVA_OPTS="-Xms2g -Xmx2g" in your environment but Elasticsearch fails to start. Which option shows a likely cause?

A The system has only 1GB of RAM available, so Elasticsearch cannot allocate 2GB.

B The syntax for ES_JAVA_OPTS is incorrect; it should be <code>ES_JAVA_OPTS=-Xms2g -Xmx2g</code> without quotes.

C Elasticsearch requires at least 4GB of RAM to start, so 2GB is too low.

D The environment variable ES_JAVA_OPTS is ignored; memory must be set in elasticsearch.yml.

💡 Hint

Check if the system has enough memory to allocate the requested heap size.

If the system has less RAM than the requested JVM heap size, Elasticsearch will fail to start.

📝 Syntax

advanced

Correct syntax for Elasticsearch repository installation on Debian

Which command correctly adds the Elasticsearch GPG key and repository on a Debian-based system?

A sudo rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch && sudo yum-config-manager --add-repo https://artifacts.elastic.co/packages/8.x/yum stable main && sudo yum update

B curl -fsSL https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add - && sudo sh -c 'echo "deb https://artifacts.elastic.co/packages/8.x/apt stable main" > /etc/apt/sources.list.d/elastic-8.x.list' && sudo apt update

C sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys https://artifacts.elastic.co/GPG-KEY-elasticsearch && sudo add-apt-repository 'deb https://artifacts.elastic.co/packages/8.x/apt stable main' && sudo apt update

D wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add - && sudo sh -c 'echo "deb https://artifacts.elastic.co/packages/8.x/apt stable main" > /etc/apt/sources.list.d/elastic-8.x.list' && sudo apt update

💡 Hint

Debian uses apt-key and sources.list.d for repositories.

Option D correctly downloads the GPG key, adds it, writes the repo to sources.list.d, and updates apt.

🚀 Application

expert

Elasticsearch cluster initial master nodes setting

You are setting up a new Elasticsearch cluster with 3 nodes. To avoid split-brain issues, which setting must you add to elasticsearch.yml on each node before starting the cluster?

A discovery.seed_hosts: ["node1", "node2", "node3"]

B cluster.initial_master_nodes: ["node1", "node2", "node3"]

C node.master: true

D cluster.name: my-cluster

💡 Hint

This setting tells Elasticsearch which nodes can be elected as master during the first cluster formation.

The cluster.initial_master_nodes setting is required on new clusters to specify the initial master-eligible nodes and prevent split-brain.