The Log Aggregator is a long-running process that collects log messages from all of the other nowcast system processes (both workers, and long-running processes like the manager) and writes them to disk files, etc. as configured in the Logging Configuration.
The log aggregator is intended for use in nowcast systems that have workers running on different hosts than the manager. For example, all of the pre- and post-processing runs on one machine but the NEMO runs are executed on a different computer server or cloud platform. When the log aggregator process is used all of the other processes publish their log messages to network sockets. The log aggregator subscribes to those sockets and processes the log messages as they are received.
It is necessary to ensure that the appropriate firewall rules are in place to allow traffic to pass between the machines on which remote workers are running and the machine that hosts the log aggregator via the logging port(s).
Since manager/worker communication, and distributed logging all use ZeroMQ ports, it is crucial to ensure that all port numbers used are unique.