we are thinking of L7 service health checking in connection manager to OS, still investing.
if you want do full balance, that is hard, I think we have many checkpoints: 1, HostDB strict RR, proxy.config.hostdb.strict_round_robin, that may make all HostDB response strict RR. 2, need a strict RR connection manager to OS, I think that will need some work. and may or may not be a design problem, as we are not guarantee to connnect all OS hosts for now. and the full balance may or may not make sense, it will depends on how many TS hosts, how many OS hosts, and how many ts2os connection/request. I'd like to have it in a full proxy env. btw: TS-316 maybe relate to your requirement too. https://issues.apache.org/jira/browse/TS-316 在 2010-12-09四的 01:18 -0300，Victor Lucero写道： > El 09-12-2010, a las 0:56, Leif Hedstrom escribió: > > > On 12/08/2010 08:45 PM, Leif Hedstrom wrote: > >> On 12/08/2010 08:36 PM, Victor Lucero wrote: > >>> Hi. > >>> Im writing a plugin to implement Load balancing. im facing some problem > >>> doing it with a remap plugin because its looks like when i alter new_host > >>> its also alter the "host" header in the http petition (and i dont want > >>> that) > >>> I need a way to alter the conection to Original Server and change the > >>> ip(so i can select between the servers in the pool). but there is no hook > >>> in this step. > >> > >> > >> You have two options: > > > > > > Well, there's a third option, I meant to say there are "two options" if you > > want to do this as a remap plugin (which makes a fair amount of sense, > > since you might want to easily configure this plugin per remap rule). > > > > The third option is to use "trunk", which has a few changes to the hooks > > and APIs. In particular, there are two useful hooks (one is merely renamed, > > but still): > > > > TS_HTTP_PRE_REMAP_HOOK > > TS_HTTP_POST_REMAP_HOOK > > > > > > the problem in the remap plugin is that not every request end in OS and the > balance will not get homogeneus. > > > > In addition, there's a new, very useful API (when running as a reverse > > proxy only): > > > > tsapi TSReturnCode TSSkipRemappingSet(TSHttpTxn txnp, int flag); > > > > > > All three of my "suggestions" probably suffers from the fact that changing > > the destination "url" also affects the cache key (if the content is > > cacheable). In most cases, that would be undesirable, so you should also > > look into using this API to control the cache key: > > > > tsapi TSReturnCode TSCacheUrlSet(TSHttpTxn txnp, const char *url, int > > length); > > > > > > As a side note, for real load balancing, we need a way to intercept all DNS > > / hostDB lookups in a plugin. So, you'd do something like > > > > map http://www.example.com/ http://real.example.com/ > > > > > > and when real.example.com is looked up in our hostDB / DNS (on every > > request), you would intercept it with a plugin (new hook required, there's > > no way to do this now afaik) that allows you to return an IP based on your > > own code. It's unclear to me right now how such a hook would interact with > > hostDB, and the existing code we have for marking IPs as down etc. (i.e. > > it's important for the core to communicate connect failures to a plugin in > > a new hook like this). It's something we should noodle about (I'll file a > > bug later), it'd be great to get core changes in before v3.0. > > > > Cheers, > > > > editing the response of the dns will do a better trick , also adding some > health test code (in the plugin. nothing really complicated) and adding a > hook near the connection to the OS for stats (also needed if i want to > implement least weight algorithm.) > > thanks. > > > -- leif > > > > -Victor Lucero.
