The OpenFaaS watchdog is responsible for starting and monitoring functions in OpenFaaS. Any binary can become a function through use of the watchdog.
The classic watchdog is currently used in all the official OpenFaaS templates. You can view the templates in the templates repository.
Pictured: technical conceptual diagram of the OpenFaaS watchdog during an invocation
Technical documentation on the classic watchdog is available belong along with a table with all configuration options.
of-watchdog is our next-generation watchdog which is in incubation within our openfaas-incubator organisation.
Pictured: various modes for the of-watchdog component
This brings version of the watchdog brings new features for high-throughput systems. The primary difference is the ability to keep a process warm between invocations. The classic watchdog forks one process per request and the new version enables a mode where that same process can be re-used repeatedly to reduce latency.