Hi, all
It is expected that new http request will not get response from the
server of which weight was changed to 0. It cannot work well with
persistence on src but work well without the persistence in lastest
snapshot.
There are two servers in my backend, and persistence on src ip has been
enabled in backend. The configuration in backend as below:
backend pool
balance roundrobin.
stick-table type ip size 200k expire 600s
stick on src
server 1 10.128.7.1:80 id 1 cookie srv1 weight 1 maxconn 0
slowstart 0s
server 2 10.128.7.2:80 id 2 cookie srv2 weight 1 maxconn 0
slowstart 0s
During continuous http requset with the same client, the stick table as
below:
# table: pool, type: ip, size:204800, used:1
0x17d2284: key=172.22.16.250 use=0 exp=599095 server_id=1
Then I set weight of server 1 to 0 use command as below:
set weight pool/1 0
And I get the weight of server 1 with command:
get weight pool/1
The result is
0 (initial 1)
So I think I have set the weight of sever1 to 0 successfully. But the
response still comes from server 1 which server 2 is expected. And the
stick table keeps the same.
I review the code of process_sticking_rules() in session.c. The codes
when server is found as below:
1403 ptr = stktable_data_ptr(rule->table.t, ts,
STKTABLE_DT_SERVER_ID);
1404 node =
eb32_lookup(&px->conf.used_server_id, stktable_data_cast(ptr, server_id));
1405 if (node) {
1406 struct server *srv;
1407
1408 srv = container_of(node, struct server,
conf.id);
1409 if ((srv->state & SRV_RUNNING) ||
1410 (px->options & PR_O_PERSIST) ||
1411 (s->flags & SN_FORCE_PRST)) {
1412 s->flags |= SN_DIRECT | SN_ASSIGNED;
1413 s->target = &srv->obj_type;
1414 }
1415 }
1416 }
1417 stktable_touch(rule->table.t, ts, 1);
Line 1409 used (srv->state & SRV_RUNNING) to check the server status.
If I used srv_is_usable() to instead such as below:
- if ((srv->state & SRV_RUNNING) ||
+ if (srv_is_usable(srv->state, srv->eweight) ||
The new request will get response from server 2 once the weight of
server 1 is set to 0. But it seems to be just a workaround.
Since the manual of haproxy about 'set weight' says that:
A typical usage of this command is to disable a server during an update
by setting its weight to zero.
I am wondering that whether the flag SRV_RUNNING of server should be
cleared or not when its weight is set to 0.
--
Best Regards,
Godbach
