On Tue, Apr 03, 2012 at 10:30:39PM +0200, Džen wrote:
}
error_page 503 @maintenance;
if ( -d $document_root/$hostid-maintenance ) {
return 503;
}
Any thoughts? Running nginx version 1.0.12 here.
First, this is a wacky config, and I don’t quite understand what
you’re trying to achieve with it. 
Here’s what happens with the request of “/”, assuming that “if”
condition holds true.
The status code is set to 503, and further processing happends in
the named location @maintenance.
It tries “$uri”, find that directory, but because argument does
not end with a slash (i.e., we’re testing a file, not directory),
this variant is ignored.
It then tries “$uri/”, and succeeds. $uri is set to
“/$hostid-maintenance/”. As documentation of “try_files” says,
the further processing is done in thi same (named) location.
What happens next is since a request now ends with a slash, the
static module handler ignores it, and a request is processed by
the index module. The index module then verifies that the
“/var/nginx/$hostid-maintenance/index.html” file exists and does
an internal redirect to a new $uri. (The fact that it does an
internal redirect is also documented.)
This in turn gets processed by the server’s default location
which is configured to return 503. Because
“recursive_error_pages” aren’t enabled, the server ends up
returning status code 503 with the standard content.
(What happens when you enable is left as an excercise to a
reader.)
When OTOH you request “/index.html”, try_files checks that the
file exists, and the processing is performed by the static
module in the context of location @maintenance. There are no
more internal redirects involved, so the server ends up sending
you the status code 503 with the contents of index.html.
I agree that this might not be obvious, but this is how it works.
The important bit here is that requests that end up with “/”, and
get processed by the index module, do an internal redirect. This
is quite logical if you think about it, because they usually
get processed by the static module, as if a request ended up with
“/” followed by the name of index file.