[Systems] mirrorbrain - sugarlabs - sql lookup error

[Peter Pöml]

Hi David (& the rest of the team),

On 11.10.2009, at 20:00, David Farning wrote:

> Arggg fixed it.
>
> Apache2/sites-available/download-testing.sugarlabs.org was pointing to
> /var/www-sugarlabs/download which was a symlink to /srv/uploads.
>
> Once the the apache config was working pointing at a normal directory
> it worked correctly.

Ah, I see.

Thanks for digging into it!


I wonder how we can make this more foolproof. I can think of two ways:

1) add documentation that explains this -- but how to make sure that  
it is not missed?

2) add a check to mod_mirrorbrain that is performed at Apache start  
time, which resolves the directory to its canonical path and checks  
whether they match. If the check fails, either prevent starting or log  
an error message.

The config typically looks like this:
     <Directory /srv/mirrors/openoffice>
         MirrorBrainEngine On
...

3) thinking more about 2), I realize that all that's needed is to  
canonicalize the directory name in the beginning, and use the  
canonicalized path instead of the directory where the config has been  
placed.


Looking at the code, I actually see a comment that confirms the above  
assumptions:

     /* XXX we should forbid symlinks in mirror_base */
     filename = apr_pstrdup(r->pool, ptr + strlen(cfg->mirror_base));


I think 3) is the way to go to prevent us from running into this again!

I'm opening an issue in my new toy, the issue tracker... ;)

Peter