Hello,
I realize that new features are not preferred at the moment but I think
this might be a usability issue and hopefully it can be considered for
2.1-dev, however, it's perfectly fine if it's decided to wait till next.
It was noted in GitHub issue #48 that there are times when a
configuration may use the server-template directive with SRV records and
simultaneously want to control weights separately using an agent-check
or through the runtime api. This patch adds a new option
"ignore-weight" to the "resolve-opts" directive.
When specified, any weight indicated within an SRV record will be
ignored. This is for both initial resolution and ongoing resolution.
I wanted to include VTC test with this, however, I could not think of
an appropriate way to do it as I suspect we may need a "fake dns server"
similar to what was made for syslog.
Thanks,
-- Daniel
>From 59381396c68d776d220e76ccc6b80e4a2f7ff068 Mon Sep 17 00:00:00 2001
From: Daniel Corbett <dcorb...@haproxy.com>
Date: Sun, 17 Nov 2019 09:48:56 -0500
Subject: [PATCH] [MEDIUM] dns: Add resolve-opts "ignore-weight"
It was noted in #48 that there are times when a configuration
may use the server-template directive with SRV records and
simultaneously want to control weights using an agent-check or
through the runtime api. This patch adds a new option
"ignore-weight" to the "resolve-opts" directive.
When specified, any weight indicated within an SRV record will
be ignored. This is for both initial resolution and ongoing
resolution.
---
doc/configuration.txt | 5 +++++
include/types/dns.h | 1 +
src/dns.c | 21 ++++++++++++---------
src/server.c | 6 +++++-
4 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/doc/configuration.txt b/doc/configuration.txt
index b17ab9064..6ce23ece4 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -11932,6 +11932,11 @@ resolve-opts <option>,<option>,...
For such case, simply enable this option.
This is the opposite of prevent-dup-ip.
+ * ignore-weight
+ Ignore any weight that is set within an SRV record. This is useful when
+ you would like to control the weights using an alternate method, such as
+ using an "agent-check" or through the runtime api.
+
* prevent-dup-ip
Ensure HAProxy's default behavior is enforced on a server: prevent re-using
an IP address already set to a server in the same backend and sharing the
diff --git a/include/types/dns.h b/include/types/dns.h
index 5a60c0708..8347e93ab 100644
--- a/include/types/dns.h
+++ b/include/types/dns.h
@@ -249,6 +249,7 @@ struct dns_options {
int pref_net_nb; /* The number of registered preferred networks. */
int accept_duplicate_ip; /* flag to indicate whether the associated object can use an IP address
already set to an other object of the same group */
+ int ignore_weight; /* flag to indicate whether to ignore the weight within the record */
};
/* Resolution structure associated to single server and used to manage name
diff --git a/src/dns.c b/src/dns.c
index 5f9e7eae5..9f422eef6 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -537,7 +537,8 @@ static void dns_check_dns_response(struct dns_resolution *res)
HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
if (srv->srvrq == srvrq && srv->svc_port == item->port &&
item->data_len == srv->hostname_dn_len &&
- !memcmp(srv->hostname_dn, item->target, item->data_len)) {
+ !memcmp(srv->hostname_dn, item->target, item->data_len) &&
+ srv->dns_opts.ignore_weight != 1) {
int ha_weight;
/* DNS weight range if from 0 to 65535
@@ -589,15 +590,17 @@ static void dns_check_dns_response(struct dns_resolution *res)
!(srv->flags & SRV_F_CHECKPORT))
srv->check.port = item->port;
- /* DNS weight range if from 0 to 65535
- * HAProxy weight is from 0 to 256
- * The rule below ensures that weight 0 is well respected
- * while allowing a "mapping" from DNS weight into HAProxy's one.
- */
- ha_weight = (item->weight + 255) / 256;
+ if (srv->dns_opts.ignore_weight != 1) {
+ /* DNS weight range if from 0 to 65535
+ * HAProxy weight is from 0 to 256
+ * The rule below ensures that weight 0 is well respected
+ * while allowing a "mapping" from DNS weight into HAProxy's one.
+ */
+ ha_weight = (item->weight + 255) / 256;
- snprintf(weight, sizeof(weight), "%d", ha_weight);
- server_parse_weight_change_request(srv, weight);
+ snprintf(weight, sizeof(weight), "%d", ha_weight);
+ server_parse_weight_change_request(srv, weight);
+ }
HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
}
}
diff --git a/src/server.c b/src/server.c
index 6b740240e..60c5ee38d 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1796,6 +1796,7 @@ static void srv_settings_cpy(struct server *srv, struct server *src, int srv_tmp
srv->resolvers_id = strdup(src->resolvers_id);
srv->dns_opts.family_prio = src->dns_opts.family_prio;
srv->dns_opts.accept_duplicate_ip = src->dns_opts.accept_duplicate_ip;
+ srv->dns_opts.ignore_weight = src->dns_opts.ignore_weight;
if (srv->dns_opts.family_prio == AF_UNSPEC)
srv->dns_opts.family_prio = AF_INET6;
memcpy(srv->dns_opts.pref_net,
@@ -2454,8 +2455,11 @@ int parse_server(const char *file, int linenum, char **args, struct proxy *curpr
else if (!strcmp(p, "prevent-dup-ip")) {
newsrv->dns_opts.accept_duplicate_ip = 0;
}
+ else if (!strcmp(p, "ignore-weight")) {
+ newsrv->dns_opts.ignore_weight = 1;
+ }
else {
- ha_alert("parsing [%s:%d]: '%s' : unknown resolve-opts option '%s', supported methods are 'allow-dup-ip' and 'prevent-dup-ip'.\n",
+ ha_alert("parsing [%s:%d]: '%s' : unknown resolve-opts option '%s', supported methods are 'allow-dup-ip', 'ignore-weight', and 'prevent-dup-ip'.\n",
file, linenum, args[cur_arg], p);
err_code |= ERR_ALERT | ERR_FATAL;
goto out;
--
2.17.1
