Hi Alex,
On Sun, Oct 02, 2011 at 06:44:43PM +0200, Piavlo wrote:
>
> Hi,
>
> There is a client which establishes a persistent tcp connection to the
> server, and haproxy in the middle which has a main server and backup server.
> Then main server goes offline , the connections are reestablished to the
> backup server just fine. The problem is that once main server is back
> the already established connections should be restablished to the main
> server. Is there a clean way to do it in haproxy?
No, I see no way to do that. In fact, there are also many people who
would like the behaviour you observe to work also with non-persistent
connections :-)
> Since there is a lot of data sent over the connections the client/server
> timeout is never reached ,so established connections continue forever
> stay on the backup server. The way I see it is to trigger a reconnect
> by haproxy automatically tearing the already established connections to
> backup server then main server is back online.
I see. The problem is that in many environments, it is just not acceptable
to break established TCP connections when a server goes back up, as it
means that repairing a server will disturb traffic. I think we could
implement an option for this, but we need to limit it to very specific
cases. What I'm thinking about is the following : when an active server
comes up :
- if it is the only active server, then it should kill all backup servers'
connections ;
- if there are backup servers associated to it (eg: by sharing a cookie),
then it should kill their connections even if it's not alone.
- later when we support spare and buddy servers, it should do the same.
It's not something obvious to do, but should not be too much difficult
either. I can add this to the roadmap.
Regards,
Willy
