a9s LogMe SPI Configuration

This document describes a9s LogMe SPI configuration.

Summary

Custom Parameter Configuration

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

The a9s LogMe 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 LogMe SPI configuration. The platform operator has to configure the property logme-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:

logme-spi:
  service_instance:
    custom_param_config:
      es_instances:
        default_value: 2
        modifiable: false

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 read in the application developer documentation for a9s LogMe.

NameDefault valueIs modifiable
curator_retention_unit30true
curator_retention_perioddaystrue
max_disk_threshold80true
es_instances5true
kibana_instances1true
logstash_instances1true
additional_groks[]true

Example Configuration

Let's build an imaginary example.

The default value for the curator_retention_period custom parameter should be 33. The custom parameter curator_retention_unit should have a default value of 'weeks' and the application developer should not be allowed to change it.

Then the configuration must look the following way:

logme-spi:
  service_instance:
    custom_param_config:
      curator_retention_period:
        default_value: 33
        modifiable: true
      curator_retention_unit:
        default_value: weeks
        modifiable: false

Notes

Additional custom parameters will be made available over time. We do not make all available custom parameters the SPIs know 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.