* push: Implement HTTP/2 server push (close#3551)
* push: Abstract header ops by embedding into new struct type
This will allow us to add more fields to customize headers in
push-specific ways in the future.
* push: Ensure Link resources are pushed before response is written
* Change header name from X-Caddy-Push to Caddy-Push
See https://caddy.community/t/caddy-server-that-returns-only-ip-address-as-text/6928/6?u=matt
In most cases, we will want to apply header operations immediately,
rather than waiting until the response is written. The exceptions are
generally going to be if we are deleting a header field or if a field is
to be overwritten. We now automatically defer header ops if deleting a
header field, and allow the user to manually enable deferred mode with
the defer subdirective.
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.
Before this change, only response headers could be manipulated with the
Caddyfile's 'header' directive.
Also handle the request Host header specially, since the Go standard
library treats it separately from the other header fields...
Use piles from which to draw config values.
Module values can return their name, so now we can do two-way mapping
from value to name and name to value; whereas before we could only map
name to value. This was problematic with the Caddyfile adapter since
it receives values and needs to know the name to put in the config.
- Fix static responder so it doesn't replace its own headers config,
and instead replaces the actual response header values
- caddyhttp.ResponseRecorder type optionally buffers response
- Add interface guards to ensure regexp matchers get provisioned
- Use default HTTP port if one is not explicitly set
- Encode middleware writes status code 200 if not written upstream
- Templates and markdown only try to execute on text responses
- Static file server sets Content-Type based on file extension only
(this whole thing -- MIME sniffing, etc -- needs more configurability)
