Re-mounting should only happen if the --prefix-routes option is set. If
this happens, the result will be a no-op as intended since the
--basepath will be "". MountableRouter and http.StripPrefix are both
no-ops with prefix set to ""
http.StripPrefix is a standard library handler which is designed to do
exactly what the inline http.HandlerFunc did (with almost the same
implementation).
In certain situations, the http.ResponseWriter passed to the URLPrefixer
may not be an http.Flusher. A simple case where this may occur is if the
Prefixer has been wrapped up in a middleware where the above middleware
wraps the ResponseWriter in a ResponseWriter that doesn't implement the
Flush method.
Previously, the Prefixer would error, which would cause the request to
fail with a 500. Instead, the condition is logged and the request is
passed unmodified to the next middleware in the chain. This effectively
disables prefixing for requests where the above ResponseWriter is not an
http.Flusher.
Misc. Changes
=============
- Some tests for "builders" were moved to server/builders_test.go to
follow with convention. We've been naming files after different things
under test and leaving the file matching the package name for support
objects-in this case a mock logger was added to that file.
Some load balancers will strip prefixes on their way to the chronograf
backend, others won't. The "--prefix-routes" parameter forces all
requests to the backend to have the prefix specified in "--basepath".
Omitting it will only cause routes to be rewritten in rendered
templates and assumes that the load balancer will remove the prefix.
Use with Caddy
==============
An easy way to test this out is using the free Caddy http server at
http://caddyserver.com.
This Caddyfile will work with the options `--basepath /chronograf
--prefix-routes` set:
```
localhost:2020 {
proxy /chronograf localhost:8888
log stdout
}
```
This Caddyfile will work with only the option `--basepath /chronograf`
set:
```
localhost:2020 {
proxy /chronograf localhost:8888 {
except /chronograf
}
log stdout
}
```
This breaks compatibility with the old behavior of --basepath, so this
requires that proxies be configured to not modify routes forwarded to
backends. The old behavior will be supported in a subsequent commit.
The httprouter used in Chronograf did not support prefixing every route
with some basepath. This caused problems for those using the --basepath
parameter in combination with a load balancer that did not strip the
basepath prefix from requests that it forwarded onto Chronograf.
To support this, MountableRouter prefixes all routes at definition time
with the supplied prefix.
lukevmorris
Andrew Watkins
Chris Goller
Tim Raymond
Jared Scheib
Alex P
Timothy J. Raymond
Hunter Trujillo