Step-by-Step Guide to Deploying an Elasticsearch Cluster with Docker on CentOS

Why use Elasticsearch? The article begins by explaining that Elasticsearch, built on Lucene, is a distributed search engine offering fast storage, search, and analysis of massive data, with RESTful APIs, sharding, and automatic resharding.

1. Pull the Elasticsearch Docker Image

Run the following command in a CentOS terminal: docker pull elasticsearch:5.6.8 The pulled image version information is displayed as JSON.

2. Create Data Directories and Open Ports

Execute the following commands to create mount points and open communication ports:

[root@localhost soft]# pwd
/home/soft
[root@localhost soft]# mkdir -p ES/config
[root@localhost soft]# cd ES
[root@localhost ES]# mkdir data1
[root@localhost ES]# mkdir data2
[root@localhost ES]# mkdir data3
[root@localhost ES]# cd ES/config/
[root@localhost ES]# firewall-cmd --add-port=9300/tcp
success
[root@localhost ES]# firewall-cmd --add-port=9301/tcp
success
[root@localhost ES]# firewall-cmd --add-port=9302/tcp
success

Note: If using ELK 6.x, set 777 permissions on data directories.

3. Create Elasticsearch Configuration Files

Using vim, create three YAML files (es1.yml, es2.yml, es3.yml) with the following contents:

es1.yml

cluster.name: elasticsearch-cluster
node.name: es-node1
network.bind_host: 0.0.0.0
network.publish_host: 192.168.9.219
http.port: 9200
transport.tcp.port: 9300
http.cors.enabled: true
http.cors.allow-origin: "*"
node.master: true
node.data: true
discovery.zen.ping.unicast.hosts: ["192.168.9.219:9300","192.168.9.219:9301","192.168.9.219:9302"]
discovery.zen.minimum_master_nodes: 2

es2.yml

cluster.name: elasticsearch-cluster
node.name: es-node2
network.bind_host: 0.0.0.0
network.publish_host: 192.168.9.219
http.port: 9201
transport.tcp.port: 9301
http.cors.enabled: true
http.cors.allow-origin: "*"
node.master: true
node.data: true
discovery.zen.ping.unicast.hosts: ["192.168.9.219:9300","192.168.9.219:9301","192.168.9.219:9302"]
discovery.zen.minimum_master_nodes: 2

es3.yml

cluster.name: elasticsearch-cluster
node.name: es-node3
network.bind_host: 0.0.0.0
network.publish_host: 192.168.9.219
http.port: 9202
transport.tcp.port: 9302
http.cors.enabled: true
http.cors.allow-origin: "*"
node.master: true
node.data: true
discovery.zen.ping.unicast.hosts: ["192.168.9.219:9300","192.168.9.219:9301","192.168.9.219:9302"]
discovery.zen.minimum_master_nodes: 2

Replace the IP address with the actual host IP if needed.

4. Increase JVM Thread Limits

Edit /etc/sysctl.conf and add: vm.max_map_count=262144 Apply the change: sysctl -p This prevents the "bootstrap checks failed max virtual memory areas" error when starting containers.

5. Launch Elasticsearch Cluster Containers

Run the following Docker commands:

docker run -e ES_JAVA_OPTS="-Xms256m -Xmx256m" -d -p 9200:9200 -p 9300:9300 -v /home/soft/ES/config/es1.yml:/usr/share/elasticsearch/config/elasticsearch.yml -v /home/soft/ES/data1:/usr/share/elasticsearch/data --name ES01 elasticsearch:5.6.8

docker run -e ES_JAVA_OPTS="-Xms256m -Xmx256m" -d -p 9201:9201 -p 9301:9301 -v /home/soft/ES/config/es2.yml:/usr/share/elasticsearch/config/elasticsearch.yml -v /home/soft/ES/data2:/usr/share/elasticsearch/data --name ES02 elasticsearch:5.6.8

docker run -e ES_JAVA_OPTS="-Xms256m -Xmx256m" -d -p 9202:9202 -p 9302:9302 -v /home/soft/ES/config/es3.yml:/usr/share/elasticsearch/config/elasticsearch.yml -v /home/soft/ES/data3:/usr/share/elasticsearch/data --name ES03 elasticsearch:5.6.8

The -e ES_JAVA_OPTS="-Xms256m -Xmx256m" option reduces the default 2 GB JVM heap to 256 MB, which can be verified with docker stats.

6. Verify the Cluster

Check node status via a browser: http://192.168.9.219:9200/_cat/nodes?pretty Use the elasticsearch-head UI for a visual overview:

docker pull mobz/elasticsearch-head:5
docker run -d -p 9100:9100 --name es-manager mobz/elasticsearch-head:5

Then open http://192.168.9.219:9100/ in a browser.

7. Additional Settings and Tips

Adjust index settings (shards, replicas) via the REST API:

curl -XPUT 'http://localhost:9200/_all/_settings?preserve_existing=true' -d '{"index.number_of_replicas":"1","index.number_of_shards":"10"}'

Key configuration parameters explained: cluster.name: unique identifier for the cluster. node.name: unique node name. index.number_of_shards: default number of primary shards (default 5). index.number_of_replicas: default number of replica shards (default 1). network.bind_host / network.publish_host: IP addresses for binding and publishing; can be replaced by network.host. http.port and transport.tcp.port: ports for HTTP and inter‑node communication. http.cors.enabled and http.cors.allow-origin: enable CORS for REST calls. node.master and node.data: designate master‑eligible and data nodes. discovery.zen.minimum_master_nodes: prevents split‑brain scenarios (formula: floor(total_master_nodes/2)+1). discovery.zen.ping.unicast.hosts: list of node IPs for cluster discovery.

Appendix

Useful commands:

View container memory usage: docker stats $(docker ps --format={{.Names}}) View container logs: docker logs <em>container_name_or_id</em> Inspect Elasticsearch configuration file entries (cluster name, node name, network settings, etc.).

The article concludes with a reminder to adjust shard and replica settings according to workload and to consider memory‑lock settings for production stability.