Cloudera Docs

Core Settings Service

The Core Configuration service has been enhanced and renamed to Core Settings service. The Core Settings service allows you to create clusters without the HDFS service and is used to store cluster-wide settings, including some settings that were previously stored in HDFS or in the legacy Core Configuration service.

Minimum Required Role: Configurator (also provided by Cluster Administrator, Limited Cluster Administrator , and Full Administrator)

Overview

The Core Settings service allows you to create more types of clusters without having to include the HDFS service. Previously, the HDFS service was required in many cases even when data was not being stored in HDFS because some services like Sentry and Spark required cluster-wide configuration files that Cloudera Manager deploys using the HDFS service. The Core Settings service provides this configuration in a standalone fashion and thus eliminates the need for an HDFS service.

Beginning with Cloudera Manager 7.7.1 the Core Settings service is implemented in a new way that changes how it is added to the cluster and what occurs during an upgrade of Cloudera Manager. There are also some potential changes to how the Cloudera Manager API is used to access configuration data stored in the Core Settings service.

New installations

For new installations, the Core Settings service is added to newly created clusters by default.

Upgrades

After you upgrade to Cloudera Manager 7.7.1 (or higher), Cloudera Manager executes several steps when the Cloudera Manager server first starts after the upgrade:
  • The Core Settings service is automatically added to clusters managed by Cloudera Manager that did not have the Core Configuration service.
  • Some Configurations will be removed from HDFS and stored in the Core Settings service. See Configuration parameters migrated to Core Settings Service for a list of these parameters.
  • If the cluster already has the legacy Core Configuration service, Cloudera Manager will update this service (but keeping the original service name), and also add a StubDFS service. Further, the Storage Operations role of the Core Configuration Service is moved to the StubDFS service. This service provides backwards compatibility for services that have a mandatory DFS service dependency, allowing access to core configuration files..

The Cloudera Manager API and the Core Settings service

Calls to the Cloudera Manager API to access configuration settings that previously were owned by HDFS will continue to work as expected without code changes using the "API Compatibility Mode". This mode transparently redirects such API calls to perform the configuration changes on the Core Settings Service and is enabled by default.

If you want to revise your code to access the settings without using the Compatibility mode, change your API consumers to target the Core Settings service instead of HDFS. Cloudera highly recommends that you test and migrate your code by disabling the API Compatibility mode to avoid any future interruptions.

You can test this code by disabling the API Compatibility mode:
  1. Open the Cloudera Manager Admin Console.
  2. Go to the HDFS service page.
  3. Click the Configuration tab.
  4. Search for the following configuration parameter: Legacy Cloudera Manager API Clients Compatibility.