.. _arch_overview_runtime:

Runtime configuration
=====================

Envoy supports “runtime” configuration (also known as "feature flags" and "decider"). Configuration
settings can be altered that will affect operation without needing to restart Envoy or change the
primary configuration. The currently supported implementation uses a tree of file system files.
Envoy watches for a symbolic link swap in a configured directory and reloads the tree when that
happens. This type of system is very commonly deployed in large distributed systems. Other
implementations would not be difficult to implement. Supported runtime configuration settings are
documented in the relevant sections of the operations guide. Envoy will operate correctly with
default runtime values and a “null” provider so it is not required that such a system exists to run
Envoy.

Runtime :ref:`configuration <config_runtime>`.