DRAFT KB-2256: "System call filters failed to install" for search server

Symptoms

The search server fails to start up with the following error:

bootstrap checks failed
system call filters failed to install; check the logs and fix your configuration or disable system call filters at your own risk

Cause

Starting in 20.4, search-server runs bootstrap checks to ensure the security and configuration of the host machine before starting up. On machines running CentOS 6, these bootstrap checks inherently fail due to limitations of the OS. 

Action

After confirming that the machine is running CentOS 6, follow these steps to disable the bootstrap checks:

1. Create a new file named elasticsearch.yml in <APPIAN_HOME>/search-server/conf/ with the following contents:
   bootstrap.system_call_filter: false
2. Start search-server

For HA deployments of search-server, this file must be created in the appropriate directory on each instance of search-server. When upgrading Appian, this configuration must be copied over to its correct location as well.