Elasticsearch:Connect to a cluster by using Cerebro

Step 1: Find the IP address to add

Step 2: Add the IP address to the whitelist

1. Log on to the Elasticsearch console and go to the Basic Information page of your cluster. In the navigation pane, choose Configuration and Management > Security Settings.

2. Click Modify to open the whitelist dialog box.

   

3. Click Configure to the right of the default group and add your IP addresses.

   • Separate multiple IP addresses or CIDR blocks with commas — no spaces before or after.

   • A single cluster supports up to 300 IP addresses or CIDR blocks.

   • To create a separate group, click Add IP Whitelist Group. Groups are for IP address management only; all IPs across groups share the same access permissions.

   Important

   Do not set the whitelist to 0.0.0.0/0 or ::/0. These configurations allow access from any IP address and pose a significant security risk. Some cluster versions (such as 7.16 and 8.5) and regions do not support these values. IPv6 whitelist support is limited to clusters using the v2 deployment architecture in the China (Hangzhou) region.

   Supported formats:

   Type	Format	Example
   IPv4 single address	A.B.C.D	192.168.0.1
   IPv4 CIDR block	A.B.C.D/N	192.168.0.0/24
   IPv4 deny all	—	127.0.0.1
   IPv4 allow all (high risk)	—	0.0.0.0/0
   IPv6 single address	—	2401:XXXX:1000:24::5
   IPv6 CIDR block	—	2401:XXXX:1000::/48
   IPv6 deny all	—	::1
   IPv6 allow all (high risk)	—	::/0

   

4. Click Confirm.

   

1. Install and configure Cerebro

Connect to your ECS instance. The following steps use a Linux system. See Connect to an ECS instance for connection instructions.

1. Install JDK 1.8 or later on the ECS instance. See Manually deploy OpenJDK.

2. Download and extract the Cerebro package.

   This example uses v0.9.0. To use the latest version, check Cerebro releases and update the download URL accordingly.

   # Download Cerebro v0.9.0
   wget https://github.com/lmenezes/cerebro/releases/download/v0.9.0/cerebro-0.9.0.tgz
   
   # Extract the package
   tar -zxvf cerebro-0.9.0.tgz

3. Open the Cerebro configuration file.

   vim cerebro-0.9.0/conf/application.conf

4. Configure the hosts parameter to point Cerebro at your Elasticsearch cluster, then save the file.

   To connect Cerebro to multiple clusters, add multiple entries to the hosts array, separated by commas.

   Parameter	Description
   host	The cluster endpoint. Use http://<VPC private endpoint>:9200 for private access or http://<public endpoint>:9200 for public access. ES clusters have HTTP enabled by default. To encrypt traffic, enable HTTPS in Configuration and Management > Security Settings. Before enabling HTTPS, update your application code to support HTTPS connections — existing HTTP-based code will stop working.
   name	Your Elasticsearch cluster ID. Find it in the cluster list in the Elasticsearch console.
   username	The username for the cluster. The default is elastic, which has full cluster permissions. For production environments, create dedicated users with scoped permissions using Elasticsearch X-Pack role management instead.
   password	The password for the specified user.

   

2. Start the Cerebro service

Start in the foreground (for debugging):

cd cerebro-0.9.0
bin/cerebro

When Cerebro starts successfully, the terminal displays a confirmation message.

Start in the background (for production environments):

cd cerebro-0.9.0
nohup bin/cerebro > cerebro.log 2>&1 &

To view logs: tail -f cerebro.log

To stop the service: pkill -f cerebro

3. Open Cerebro in a browser and connect to the cluster

1. In the ECS security group, open port 9000 for inbound traffic from the IP address of the device you want to access Cerebro from. See Add a security group rule for steps.

   

2. In a browser, go to http://<Public IP address of the ECS instance>:9000.

3. On the Cerebro login page, the clusters configured in application.conf appear. Click a cluster to connect.

   

4. After connecting, the Cerebro console displays cluster health, indexes, and other management options.

   

For more information about using Cerebro, see the Cerebro documentation.

Cerebro fails to start

Check the following:

• JDK not installed or version is earlier than 1.8. Run java -version to verify. If the version is below 1.8, install a compatible JDK.

• Port 9000 is already in use. Change the port by setting http.port to a different value in application.conf.

• The startup script lacks execute permissions. Run chmod +x bin/cerebro to add them.

Failed to connect to the Elasticsearch cluster

Check the following:

• IP address whitelist not configured. Verify the IP address of the Cerebro host is added to the correct whitelist (VPC private or public) in the Elasticsearch console.

• Incorrect endpoint or port in the configuration. Confirm the host value in application.conf matches the cluster endpoint and uses port 9200.

• ECS security group blocking traffic. Confirm the security group allows inbound traffic on port 9200 (Elasticsearch) and port 9000 (Cerebro).

• Incorrect username or password. Verify the credentials in application.conf are correct.