error_page

[Maxim Dounin]

Hello!

On Wed, Oct 20, 2010 at 09:40:11PM +0400, Igor Sysoev wrote:

> On Wed, Oct 20, 2010 at 09:35:20PM +0400, Maxim Dounin wrote:
> 
> > Hello!
> > 
> > On Wed, Oct 20, 2010 at 07:03:37PM +0200, Witold Filipczyk wrote:
> > 
> > > On Wed, Oct 20, 2010 at 08:25:42PM +0400, Maxim Dounin wrote:
> > > > Hello!
> > > > 
> > > > On Wed, Oct 20, 2010 at 05:58:09PM +0200, witekfl at gazeta.pl wrote:
> > > > 
> > > > > On Wed, Oct 20, 2010 at 07:21:19PM +0400, Igor Sysoev wrote:
> > > > > > On Wed, Oct 20, 2010 at 05:10:59PM +0200, witekfl Gazeta.pl wrote:
> > > > > > 
> > > > > > > Hi,
> > > > > > > probably better place for these questions would be nginx-users, but I ask
> > > > > > > here.
> > > > > > > I want to serve static pages as error codes but without changing the error
> > > > > > > code.
> > > > > > > 
> > > > > > > Now if:
> > > > > > > error_page 404 http://blablabla.com/404.html
> > > > > > > There is 302 and next 200 OK
> > > > > > > I want 404.
> > > > > > > 
> > > > > > > error_page 404 /404.html
> > > > > > > it works, but:
> > > > > > > if there is:
> > > > > > > location = /404.html {
> > > > > > > internal;
> > > > > > > }
> > > > > > > then cannot be a normal location
> > > > > > > location = /404.html {
> > > > > > > },
> > > > > > > so request such as http://blabla1.com/404.html won't work.
> > > > > > > 
> > > > > > > error_page 404 @404;
> > > > > > > location @404 {
> > > > > > >    root /blabla;
> > > > > > >    index 404.html;
> > > > > > > }
> > > > > > > doesn't work either
> > > > > > > 
> > > > > > > There must be some way to achieve it.
> > > > > > > How?
> > > > > > 
> > > > > > I do not understand the problem. With this configuration
> > > > > > 
> > > > > > error_page  404 /404.html;
> > > > > > locaiton = /404.html {
> > > > > >     internal;
> > > > > >     root /path/to/page;
> > > > > > }
> > > > > > 
> > > > > > you will get 404 code with /404.html body for both requests:
> > > > > > 
> > > > > > http://blabla1.com/non-existant.html
> > > > > > http://blabla1.com/404.html
> > > > > 
> > > > > Yes, but I want:
> > > > > http://blabla1.com/404.html to be 200 OK and serve http://blabla1.com/404.html
> > > > > not /path/to/page/404.html
> > > > 
> > > > Something like this:
> > > > 
> > > >     error_page 404 @notfound;
> > > > 
> > > >     location @notfound {
> > > >         rewrite ^ /404.html break;
> > > >         root /path/to/page;
> > > >     }
> > > > 
> > > > should do the trick.
> > > 
> > > Yes, it works. Thanks!
> > > Could you explain, why it works.
> > > Why this rewrite is required?
> > > Does it mean that for 404 by default /404.html is requested or not?
> > 
> > Short answer:
> > 
> > You have to use rewrite to map request to correct file.
> > 
> > Long answer:
> > 
> > Normally nginx uses error pages in the same URI namespace as the 
> > site itself (i.e. error_page 404 /404.html; will use the same file 
> > as available though normal /404.html request).  Note that 
> > "internal" doesn't introduce another namespace, it's only protects 
> > some part of the namespace from direct outside access.
> > 
> > If you want for some reason to introduce another namespace which 
> > won't interfere with site's one - you have to use named locations.
> > 
> > On the other hand, redirect to named location doesn't change URI, 
> > so request to "/something-not-here" with
> > 
> >     error_page 404 @notfound;
> > 
> > will result in request to "/something-not-here" being processed in 
> > location @notfound.  This will map to <root> + <uri> file, i.e. 
> > "/path/to/page/something-not-here".  To map request to correct 
> > file one have to use "rewrite".  With
> > 
> >     location @notfound {
> >         rewrite ^ /404.html break;
> >         root /path/to/page;
> >     }
> > 
> > any request in location @notfound will be mapped to 
> > "/path/to/page/404.html" file.
> > 
> > [...here should be explanation why "alias" won't work instead of 
> > root + rewrite, but I'm bored...]
> > 
> > Note well: I don't recommend this aproach as I consider having 
> > error pages in site's namespace is a good practice.  Additionally, 
> > this aproach is less efficient than normal error pages.  I've just 
> > outlined how to do what you're asked for.
> 
> This configuraion
> 
> error_page  404 /404.html;
> locaiton = /404.html {
>     internal;
>     root /path/to/page;
> }
> 
> does the same for outside observer: it always returns 404 with /404.html body.

No, there is a difference for "/404.html" request.

With 

    root /path/to/site;
    error_page 404 /404.html
    location = /404.html {
        internal;
        root /path/to/page;
    }

it will return code 404 with /path/to/page/404.html body.

With

    root /path/to/site;
    error_page 404 /
    location @notfound {
        rewrite ^ /404.html break;
        root /path/to/page;
    }

it will return code 200 with /path/to/site/404.html body.

Maxim Dounin