Skip to main content
Version: Develop

a9s Search SPI Configuration

This document describes a9s Search SPI configuration.

Custom Parameter Configuration

The a9s Search SPI handles custom parameters for all service instances. It does configuration and validation of custom parameters.

The a9s Search SPI defines default values for certain custom parameters. Also, it defines whether a custom parameter can be set by the application developer.

The platform operator can overwrite those choices by changing the a9s Search SPI configuration. The platform operator has to configure the property opensearch-spi.service_instance.custom_param_config. The property value must be a hash. Every key in that hash stands for a custom parameter and the value for every key contains the configuration for that particular parameter. The configuration for a particular param is a hash consisting of the following optional keys: default_value and modifiable. The key default_value specifies the default value for that parameter and modifiable specifies whether the application developer is allowed to set that custom parameter. For example:

default_value: ['TLSv1.2', 'TLSv1.3']
modifiable: true

Default Custom Parameter Configuration

The following table contains custom parameters that are configurable by the platform operator. The meaning of those custom parameters can be found below.

NameDefault valueIs modifiable


The parameter tls-protocols maps to the OpenSearch's configuration parameter, see Limiting TLS Protocols Used by the Server.

Because it is insecure, the OpenSearch security plugin disables TLSv1 by default.

The value for tls-protocols must be an array with the values TLSv1.3 and/or TLSv1.2. Only Java format is supported.


The parameter tls-ciphers maps to the OpenSearch's configuration parameter, see Configuring Cipher Suites.

The value for tls-ciphers must be an array of strings that list the cipher names. Only Java format is supported.

a9s Search SPI does no validation for the tls-ciphers value except that it must be an array of strings or null.

Example Configuration

The following is an example for the default custom parameter configuration.

The default value for the custom parameter tls-protocols is TLSv1.3. Additionally, the application developer should not be allowed to change it.

Then the configuration must look the following way:

default_value: ['TLSv1.3']
modifiable: false

Per Plan Configuration

Take a look at Service Plans documentation if you want to configure the custom parameters per plan.


Additional custom parameters will be made available over time. We do not make all available custom parameters the SPIs knows available to the platform operator from the beginning.

During the SPI startup, the configuration the platform operator made will be checked. When it's invalid, the SPI will not start up.