* v2: add documentation for circuit breaker config and "random selection" load balancing policy
* v2: rename circuit breaker config inline key from `type` to `breaker` to avoid json key clash between the `circuit_breaker` type and the `type` field of the generic circuit breaker Config struct used by circuit breaking implementations
* v2: restore the circuit breaker inline key to `type` and rename the name circuit breaker config field from `Type` to `Factor`
This commit goes a long way toward making automated documentation of
Caddy config and Caddy modules possible. It's a broad, sweeping change,
but mostly internal. It allows us to automatically generate docs for all
Caddy modules (including future third-party ones) and make them viewable
on a web page; it also doubles as godoc comments.
As such, this commit makes significant progress in migrating the docs
from our temporary wiki page toward our new website which is still under
construction.
With this change, all host modules will use ctx.LoadModule() and pass in
both the struct pointer and the field name as a string. This allows the
reflect package to read the struct tag from that field so that it can
get the necessary information like the module namespace and the inline
key.
This has the nice side-effect of unifying the code and documentation. It
also simplifies module loading, and handles several variations on field
types for raw module fields (i.e. variations on json.RawMessage, such as
arrays and maps).
I also renamed ModuleInfo.Name -> ModuleInfo.ID, to make it clear that
the ID is the "full name" which includes both the module namespace and
the name. This clarity is helpful when describing module hierarchy.
As of this change, Caddy modules are no longer an experimental design.
I think the architecture is good enough to go forward.
This migrates a feature that was previously reserved for enterprise
users, according to https://github.com/caddyserver/caddy/issues/2786.
The local circuit breaker is a simple metrics counter that can cause
the reverse proxy to consider a backend unhealthy before it actually
goes offline, by measuring recent latencies over a sliding window.
Credit to Danny Navarro
