Re: [wccpd-devel] kernel wccp support

[Eduardo J. B. <ej...@ne...>]

On Tue, 2002-01-29 at 20:27, Blues wrote:
    On 29 Jan 2002, Eduardo J. Blanco wrote:
    >     Few reflections:
    >     - location of scripts - I don't know where should it be, maybe in 
    >     /etc/wccp/scripts ?
    > Sigh... I don't specially like scripts under /etc (yeah, I know,
    > /etc/rc.d).  What does the FSSTD has to say about it?  IIRC, GNU tends
    > to use /usr/libexec for that.
    
    I'll look at that in  some free time.
    
    This is strange thing... 
    1. This can be changed to make something work otherwise (esp. other marks)  
    -> /etc/......
    2. like other scripts it can be run-by-hand by root -> /usr/sbin
    3. Maybe standards(TM) are talking something about this kind of files?
    4. I really shure it  shouldn't be in /usr/lib/wccpd - this is not any 
    library.
    
    ...so... maybe move it to /var/lib/wccpd ? AFAIR FHS says that there 
    should be any of program datas.
    
    From _user_ point the best thing would be /usr/sbin ....
    
    Am I making to much flame ? ;)
    
Don't worry about the flame.

IMHO, the user shouldn't need to call these scripts directly (because
wccpd will get confused), and they are not program data either.  That's
why I put it libexec (from ./configure --help):

--libexecdir=DIR        program executables in DIR [EPREFIX/libexec]

The way I see it, these scripts are auxiliary executables needed -only-
by wccpd.

    >     - dc called in scripts - ugly :)
    > Agreed.  Any way to convert a decimal number to hex or viceversa?  ip
    > rule, iptables and the like all differ slightly on what they expect. :-(
    >     - all caches should be called from some configuration file (maybe in 
    >     /etc/wccp/wccpd.conf.
    > Sorry, I don't understand this... Do you want a config file to list the
    > valid caches?
    
    This 2 thing are connected (in my mind ;)
    I think that wccpd should call all of the externel programs (ip, ipvs). 
    Only iptables/ipchains should stay for the end-user.
    Now - if it will be done (should, I think...):
    1. one config-file will drive everything. eg. config:
    cache {
    	server proxy1.bla.bla.pl;
    	wccp-protocol 1;
    	encapsulation gre;
    	fw-mark 0x80;
    }
    2. scripts location will be no problem anymore (no scripts :)  )
    3. system log will be more reliable - now only connection of new cache is 
    noticed. Disconnection isn't. Some diagnostics can be made...? :)
    
Sigh... I really don't like this option.  I always wanted to make wccpd
as portable as possible, that's why I split the OS related stuff from
the WCCP protocol itself.  You could write similar scripts for BSD, or
whatever.  Making wccpd call the programs directly only imposes a
limitation, IMHO.

OTOH, some of the scripts for WCCP v2 will need to call
ipchains/iptables to cope with dynamic service groups. (ie. services
described by the webcache dynamically)

I'm planning to add a config file for WCCPv2, as I have pretty much no
other option.  I'll take the chance to do something like you suggested.

    Sure - almost everything can be done by smarter script, but... its not 
    "clean" solution. Point 3 can't be done in current model.
    
    Disadvantages of making it that way:
    - it will be external-programs-dependent
    - no easy way to change proxies on-fly. Solution of that can be some 
    socket or something like that + some small external program for 
    management.
    
    Is it clear?

About point #3, there are 3 conditions for a cache to 'leave':
1) Timeout - presumably the cache is down or rebooted, and it stopped
sending correct I_AM_HERE messages.
2) The designated cache took it out of the assignment hash.
3) wccpd is about to exit.

In all three cases, you should see something like:
WebCache at xxx.xxx.xxx.xxx disabled

Let me know if you don't.

I could change those messages to something like:
WebCache at xxx.xxx.xxx.xxx expired
WebCache at xxx.xxx.xxx.xxx disabled by designated WebCache
WebCache at xxx.xxx.xxx.xxx disabled by wccpd shutdown

About the second problem you describe, I plan to use a default entry for
non-declared caches.  WCCP v2 would, of course, fix most of this issues.

--ejbs