MINOR: acl: add fetch for server session rate
Considering there is no option yet for maxconnrate for servers, I wrote
an ACL to check a backend server session rate which we use to send to an
"overflow" backend to prevent latency responses to our clients (very
sensitive latency requirements).
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 81cd231..7e9f069 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -8021,6 +8021,20 @@
acl being_scanned be_sess_rate gt 100
redirect location /denied.html if being_scanned
+srv_sess_rate(<backend>/<server>) <integer>
+ Returns true when the sessions creation rate on the server matches the
+ specified values or ranges, in number of new sessions per second. This is
+ used to switch to an alternate backend when an expensive or fragile one
+ reaches too high a session rate, or to limit abuse of service (eg. prevent
+ latent requests from overloading servers).
+
+ Example :
+ # Redirect to a separate back
+ acl srv1_full srv_sess_rate(be1/srv1) gt 50
+ acl srv2_full srv_sess_rate(be1/srv2) gt 50
+ use_backend be2 if srv1_full or srv2_full
+
+
connslots <integer>
connslots(<backend>) <integer>
The basic idea here is to be able to measure the number of connection "slots"
diff --git a/src/backend.c b/src/backend.c
index f4b90ce..96545a9 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1587,6 +1587,20 @@
return 1;
}
+/* set temp integer to the number of enabled servers on the proxy.
+ * Accepts exactly 1 argument. Argument is a server, other types will lead to
+ * undefined behaviour.
+ */
+static int
+acl_fetch_srv_sess_rate(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
+ const struct arg *args, struct sample *smp)
+{
+ smp->flags = SMP_F_VOL_TEST;
+ smp->type = SMP_T_UINT;
+ smp->data.uint = read_freq_ctr(&args->data.srv->sess_per_sec);
+ return 1;
+}
+
/* Note: must not be declared <const> as its list will be overwritten.
* Please take care of keeping this list alphabetically sorted.
*/
@@ -1601,6 +1615,7 @@
{ "srv_conn", acl_parse_int, acl_fetch_srv_conn, acl_match_int, ACL_USE_NOTHING, ARG1(1,SRV) },
{ "srv_id", acl_parse_int, acl_fetch_srv_id, acl_match_int, ACL_USE_RTR_INTERNAL, 0 },
{ "srv_is_up", acl_parse_nothing, acl_fetch_srv_is_up, acl_match_nothing, ACL_USE_NOTHING, ARG1(1,SRV) },
+ { "srv_sess_rate", acl_parse_int, acl_fetch_srv_sess_rate, acl_match_int, ACL_USE_NOTHING, ARG1(1,SRV) },
{ NULL, NULL, NULL, NULL },
}};