MINOR: lb: allow redispatch when using consistent hash
Redispatch traditionally only worked for cookie based persistence.
Adding redispatch support for consistent hash based persistence - also
update docs.
Reported by Oskar Stenman on discourse:
https://discourse.haproxy.org/t/balance-uri-consistent-hashing-redispatch-3-not-redispatching/3344
Should be backported to 1.8.
Cc: Lukas Tribus <lukas@ltri.eu>
diff --git a/doc/configuration.txt b/doc/configuration.txt
index dc1f222..97b9f82 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -6764,8 +6764,8 @@
definitely stick to it because they cannot flush the cookie, so they will not
be able to access the service anymore.
- Specifying "option redispatch" will allow the proxy to break their
- persistence and redistribute them to a working server.
+ Specifying "option redispatch" will allow the proxy to break cookie or
+ consistent hash based persistence and redistribute them to a working server.
It also allows to retry connections to another server in case of multiple
connection failures. Of course, it requires having "retries" set to a nonzero
diff --git a/include/proto/lb_chash.h b/include/proto/lb_chash.h
index a0ebf69..679dff3 100644
--- a/include/proto/lb_chash.h
+++ b/include/proto/lb_chash.h
@@ -28,7 +28,7 @@
void chash_init_server_tree(struct proxy *p);
struct server *chash_get_next_server(struct proxy *p, struct server *srvtoavoid);
-struct server *chash_get_server_hash(struct proxy *p, unsigned int hash);
+struct server *chash_get_server_hash(struct proxy *p, unsigned int hash, const struct server *avoid);
#endif /* _PROTO_LB_CHASH_H */
diff --git a/src/backend.c b/src/backend.c
index 3c1620b..c92e761 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -165,7 +165,7 @@
* If any server is found, it will be returned. If no valid server is found,
* NULL is returned.
*/
-static struct server *get_server_sh(struct proxy *px, const char *addr, int len)
+static struct server *get_server_sh(struct proxy *px, const char *addr, int len, const struct server *avoid)
{
unsigned int h, l;
@@ -186,7 +186,7 @@
h = full_hash(h);
hash_done:
if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
- return chash_get_server_hash(px, h);
+ return chash_get_server_hash(px, h, avoid);
else
return map_get_server_hash(px, h);
}
@@ -203,7 +203,7 @@
* algorithm out of a tens because it gave him the best results.
*
*/
-static struct server *get_server_uh(struct proxy *px, char *uri, int uri_len)
+static struct server *get_server_uh(struct proxy *px, char *uri, int uri_len, const struct server *avoid)
{
unsigned int hash = 0;
int c;
@@ -239,7 +239,7 @@
hash = full_hash(hash);
hash_done:
if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
- return chash_get_server_hash(px, hash);
+ return chash_get_server_hash(px, hash, avoid);
else
return map_get_server_hash(px, hash);
}
@@ -253,7 +253,7 @@
* is returned. If any server is found, it will be returned. If no valid server
* is found, NULL is returned.
*/
-static struct server *get_server_ph(struct proxy *px, const char *uri, int uri_len)
+static struct server *get_server_ph(struct proxy *px, const char *uri, int uri_len, const struct server *avoid)
{
unsigned int hash = 0;
const char *start, *end;
@@ -296,7 +296,7 @@
hash = full_hash(hash);
if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
- return chash_get_server_hash(px, hash);
+ return chash_get_server_hash(px, hash, avoid);
else
return map_get_server_hash(px, hash);
}
@@ -315,7 +315,7 @@
/*
* this does the same as the previous server_ph, but check the body contents
*/
-static struct server *get_server_ph_post(struct stream *s)
+static struct server *get_server_ph_post(struct stream *s, const struct server *avoid)
{
unsigned int hash = 0;
struct http_txn *txn = s->txn;
@@ -370,7 +370,7 @@
hash = full_hash(hash);
if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
- return chash_get_server_hash(px, hash);
+ return chash_get_server_hash(px, hash, avoid);
else
return map_get_server_hash(px, hash);
}
@@ -396,7 +396,7 @@
* is returned. If any server is found, it will be returned. If no valid server
* is found, NULL is returned.
*/
-static struct server *get_server_hh(struct stream *s)
+static struct server *get_server_hh(struct stream *s, const struct server *avoid)
{
unsigned int hash = 0;
struct http_txn *txn = s->txn;
@@ -466,13 +466,13 @@
hash = full_hash(hash);
hash_done:
if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
- return chash_get_server_hash(px, hash);
+ return chash_get_server_hash(px, hash, avoid);
else
return map_get_server_hash(px, hash);
}
/* RDP Cookie HASH. */
-static struct server *get_server_rch(struct stream *s)
+static struct server *get_server_rch(struct stream *s, const struct server *avoid)
{
unsigned int hash = 0;
struct proxy *px = s->be;
@@ -511,13 +511,13 @@
hash = full_hash(hash);
hash_done:
if (px->lbprm.algo & BE_LB_LKUP_CHTREE)
- return chash_get_server_hash(px, hash);
+ return chash_get_server_hash(px, hash, avoid);
else
return map_get_server_hash(px, hash);
}
/* random value */
-static struct server *get_server_rnd(struct stream *s)
+static struct server *get_server_rnd(struct stream *s, const struct server *avoid)
{
unsigned int hash = 0;
struct proxy *px = s->be;
@@ -528,7 +528,7 @@
/* ensure all 32 bits are covered as long as RAND_MAX >= 65535 */
hash = ((uint64_t)random() * ((uint64_t)RAND_MAX + 1)) ^ random();
- return chash_get_server_hash(px, hash);
+ return chash_get_server_hash(px, hash, avoid);
}
/*
@@ -639,7 +639,7 @@
case BE_LB_LKUP_MAP:
if ((s->be->lbprm.algo & BE_LB_KIND) == BE_LB_KIND_RR) {
if ((s->be->lbprm.algo & BE_LB_PARM) == BE_LB_RR_RANDOM)
- srv = get_server_rnd(s);
+ srv = get_server_rnd(s, prev_srv);
else if (s->be->lbprm.algo & BE_LB_LKUP_CHTREE)
srv = chash_get_next_server(s->be, prev_srv);
else
@@ -658,12 +658,12 @@
if (conn && conn->addr.from.ss_family == AF_INET) {
srv = get_server_sh(s->be,
(void *)&((struct sockaddr_in *)&conn->addr.from)->sin_addr,
- 4);
+ 4, prev_srv);
}
else if (conn && conn->addr.from.ss_family == AF_INET6) {
srv = get_server_sh(s->be,
(void *)&((struct sockaddr_in6 *)&conn->addr.from)->sin6_addr,
- 16);
+ 16, prev_srv);
}
else {
/* unknown IP family */
@@ -678,7 +678,7 @@
break;
srv = get_server_uh(s->be,
c_ptr(&s->req, -http_uri_rewind(&s->txn->req)),
- s->txn->req.sl.rq.u_l);
+ s->txn->req.sl.rq.u_l, prev_srv);
break;
case BE_LB_HASH_PRM:
@@ -688,22 +688,22 @@
srv = get_server_ph(s->be,
c_ptr(&s->req, -http_uri_rewind(&s->txn->req)),
- s->txn->req.sl.rq.u_l);
+ s->txn->req.sl.rq.u_l, prev_srv);
if (!srv && s->txn->meth == HTTP_METH_POST)
- srv = get_server_ph_post(s);
+ srv = get_server_ph_post(s, prev_srv);
break;
case BE_LB_HASH_HDR:
/* Header Parameter hashing */
if (!s->txn || s->txn->req.msg_state < HTTP_MSG_BODY)
break;
- srv = get_server_hh(s);
+ srv = get_server_hh(s, prev_srv);
break;
case BE_LB_HASH_RDP:
/* RDP Cookie hashing */
- srv = get_server_rch(s);
+ srv = get_server_rch(s, prev_srv);
break;
default:
diff --git a/src/lb_chash.c b/src/lb_chash.c
index 7e188ac..186e87a 100644
--- a/src/lb_chash.c
+++ b/src/lb_chash.c
@@ -313,9 +313,10 @@
* the closest distance from the value of <hash>. Doing so ensures that even
* with a well imbalanced hash, if some servers are close to each other, they
* will still both receive traffic. If any server is found, it will be returned.
+ * It will also skip server <avoid> if the hash result ends on this one.
* If no valid server is found, NULL is returned.
*/
-struct server *chash_get_server_hash(struct proxy *p, unsigned int hash)
+struct server *chash_get_server_hash(struct proxy *p, unsigned int hash, const struct server *avoid)
{
struct eb32_node *next, *prev;
struct server *nsrv, *psrv;
@@ -367,7 +368,7 @@
}
loop = 0;
- while (p->lbprm.chash.balance_factor && !chash_server_is_eligible(nsrv)) {
+ while (nsrv == avoid || (p->lbprm.chash.balance_factor && !chash_server_is_eligible(nsrv))) {
next = eb32_next(next);
if (!next) {
next = eb32_first(root);