proxy: Fix #1574; health check now respects hostname when upstream Host header is configured (#1577)

* Implement adding Host header to health check

* Fix type problems

* Fix duplicate function, Replace args

* Add debugging

* Add debugging

* Add debugging

* Add debugging

* Attempt to set req.Host instead of the header

* Clean up debugging

* Fix missing newline

* Fix spelling

* Add test, refactoring

* Fix with gofmt

* Add error check on NewRequest

* Create list of index files based on extensions and check on a per config
basis

* remove log lines

* fixed tests

* made gofmt suggested change

* Changes made to simplify

browse: fix arbitrary ordering of directories with sort=size

* Respect the 'insecure_skip_verify' for the health check.

* WIP: Trying to add a test. Non functional.

* Fixing tests.

* Creating better error messages.

* Optimize two more error messages.

* Move the tests into an extra function.

* Add a shutdown function and context to staticUpstream so that running goroutines can be cancelled. Add a GetShutdownFunc to Upstream interface to expose the shutdown function to the caddy Controller for performing it on restarts.

* Make fakeUpstream implement new Upstream methods.

Implement new Upstream method for fakeWSUpstream as well.

* Rename GetShutdownFunc to Stop(). Add a waitgroup to the staticUpstream for controlling individual object's goroutines. Add the Stop function to OnRestart and OnShutdown. Add tests for checking to see if healthchecks continue hitting a backend server after stop has been called.

* Go back to using a stop channel since the context adds no additional benefit.
Only register stop function for onShutdown since it's called as part of restart.

* Remove assignment to atomic value

* Incrementing WaitGroup outside of goroutine to avoid race condition. Loading atomic values in test.

* Linting: change counter to just use the default zero value instead of setting it

* Clarify Stop method comments, add comments to stop channel and waitgroup and remove out of date comment about handling stopping the proxy. Stop the ticker when the stop signal is sent

* Revert "browse: sort listing by dir first (#1527)"

 commit 4e1229e7.

* Add new browse sort order  namedirfirst. Make namedirfirst default sort

init: Make CADDYPATH equal across init scripts

Previously directories have been merely pulled to the front, and then
sorted arbitrarily. That is, their order among themselves depended on
the filesystem implementations. Something opaque to the visitor.

This fixes said inconsistency, and implements the by-size-then-by-name
order I initially intended for this.

See also https://github.com/mholt/caddy/pull/1272#issue-191256343

* Add Event Hook plugins to DescribePlugins function

* Update plugins.go

* Update plugins.go

* add Hook

* update hooks

* remove parenthesis

* Update requests

* Default Browse sort by Dir, File

* Ignore temp template files

* Add folder to test

* unneeded chagne

HTTP redirects can use host-relative URLs. See discussion in #1497.

* Use helper functions in staticfiles to redirect.

Previously the browse package invoked staticfiles.Redirect when
redirecting clients who requested a directory but with a Request-URI
that did not contain a trailing '/'. staticfiles.Redirect only used a
relative URI. This change defers the decision of how to format the
Location header value to the helper methods in the staticfiles package.

* Update const URLPathCtxKey in browse package.

* Add the first policy which sends the request to the first available host

* Make the error message clear. As we expect the second not first upstream
host.

* Added Const for CtxKeys

* Move CtxKey Const declarations

* Fixed tests

* fix test

* staticfiles: add Content-Length header (closes #1479)

* make linter happy, rename "Html" in identifiers to "HTML"

systemd README: set mode of caddy.service to 644 instead of 744

* Fixed issue with {path} actually {uri}

* Test added for path rewrite

* add in uri_escaped

* added rewrite_uri and test

* fix broken test.  Just checks for existance of rewrite header

* gitignore

* Use context to store uri value

* ignore .vscode

* tidy up, removal of comments and invalidated tests

* Remove commented out code.

* added comment as requested by lint

* fixed spelling mistake

* clarified code with variable name

* added context for uri and test

* added TODO comment to move consts

* Fixed #1484

Fixed a nil pointer runtime error in newConnHijackerTransport,
where the access to the TLSClientConfig did not check for nil values.

* Minor improvement to UseInsecureTransport

This prevents overwriting a possibly preexisting TLSClientConfig,
even though only a single field should be changed.

* add support for listener middleware

* add proxyprotocol directive

* make caddy.Listener interface required

* Remove tcpKeepAliveListener wrapper from Serve()
This is now done in the Listen() function, along with other potential middleware.

* Fix for missing content-length header when using QUIC

If request.ContentLength is set then it will be used instead of getting
it from request.Header map since quic-go(lucas-clemente/quic-go@bb24be8)
will not store (and pass) the Content-Length header using its header
map.

This fixes a potential issue where FastCGI POST requests body empty when
QUIC is enabled. (#1370)

* Change the data type for fastcgi contentLength to int64

quic-go uses int64 for contentLength

* Fix an error for undeclared variable

* Fix test for fcgiclient

the data type for contentLength

Log certificate location

templates: Set MIME type

* Support realms with basic authentication

* Add test for default basicauth directive in which realm is not specified

* Correct typo: missing space

* Remove 'path' subdirective

This could have just as easily been a tls directive property in the
Caddyfile, but I figure if these challenges are being disabled, it's
because of port availability or process privileges, both of which would
affect all sites served by this process. The names of the flag are long
but descriptive.

I've never needed this but I hear of quite a few people who say they
need this ability, so here it is.

httpserver: Flags to customize HTTP and HTTPS ports (including for ACME challenges)

Adding ServerIP context