Before you dig into reading this guide, have you tried asking OpsGPT what this log means? You’ll receive a customized analysis of your log.
Try OpsGPT now for step-by-step guidance and tailored insights into your OpenSearch operation.
Briefly, this error occurs when the Hadoop authentication method is set to [SIMPLE], but a Kerberos principal is provided. This mismatch in configuration causes the error. To resolve this, you can either change the Hadoop authentication method to Kerberos if you intend to use Kerberos for authentication, or remove the Kerberos principal if you want to use the SIMPLE authentication method. Ensure that the authentication method matches the type of principal provided.
For a complete solution to your to your search operation, try for free AutoOps for Elasticsearch & OpenSearch . With AutoOps and Opster’s proactive support, you don’t have to worry about your search operation – we take charge of it. Get improved performance & stability with less hardware.
This guide will help you check for common problems that cause the log ” Hadoop authentication method is set to [SIMPLE]; but a Kerberos principal is ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: repositories, plugins.
Overview
A plugin is used to enhance the core functionalities of OpenSearch. OpenSearch provides some core plugins as a part of their release installation. In addition to those core plugins, it is possible to write your own custom plugins as well. There are several community plugins available on GitHub for various use cases.
Examples
Get all of the instructions for the plugin:
sudo bin/opensearch-plugin -h
Installing the S3 plugin for storing OpenSearch snapshots on S3:
sudo bin/opensearch-plugin install repository-s3
Removing a plugin:
sudo bin/opensearch-plugin remove repository-s3
Installing a plugin using the file’s path:
sudo bin/opensearch-plugin install file:///path/to/plugin.zip
Notes and good things to know
- Plugins are installed and removed using the opensearch-plugin script, which ships as a part of the OpenSearch installation and can be found inside the bin/ directory of the OpenSearch installation path.
- A plugin has to be installed on every node of the cluster and each of the nodes has to be restarted to make the plugin visible.
- You can also download the plugin manually and then install it using the opensearch-plugin install command, providing the file name/path of the plugin’s source file.
- When a plugin is removed, you will need to restart every OpenSearch node in order to complete the removal process.
Common issues
- Managing permission issues during and after plugin installation is the most common problem. If OpenSearch was installed using the DEB or RPM packages then the plugin has to be installed using the root user. Otherwise you can install the plugin as the user that owns all of the OpenSearch files.
- In the case of DEB or RPM package installation, it is important to check the permissions of the plugins directory after you install it. You can update the permission if it has been modified using the following command:
chown -R opensearch:opensearch path_to_plugin_directory
- If your OpenSearch nodes are running in a private subnet without internet access, you cannot install a plugin directly. In this case, you can simply download the plugins and copy the files inside the plugins directory of the OpenSearch installation path on every node. The node has to be restarted in this case as well.
Log Context
Log “Hadoop authentication method is set to [SIMPLE]; but a Kerberos principal is” classname is HdfsRepository.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :
// Check if the user added a principal to use; and that there is a keytab file provided
String kerberosPrincipal = repositorySettings.get(CONF_SECURITY_PRINCIPAL);
// Check to see if the authentication method is compatible
if (kerberosPrincipal != null && authMethod.equals(AuthenticationMethod.SIMPLE)) {
logger.warn("Hadoop authentication method is set to [SIMPLE]; but a Kerberos principal is " +
"specified. Continuing with [KERBEROS] authentication.");
SecurityUtil.setAuthenticationMethod(AuthenticationMethod.KERBEROS; hadoopConfiguration);
} else if (kerberosPrincipal == null && authMethod.equals(AuthenticationMethod.KERBEROS)) {
throw new RuntimeException("HDFS Repository does not support [KERBEROS] authentication without " +
"a valid Kerberos principal and keytab. Please specify a principal in the repository settings with [" +
