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.

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 463d1727599f2cb47c1d1a13981c83143ae00e88..2407fcb01a679310f1e3f094058efd848c451442 100644 (file)
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -11931,6 +11931,11 @@ 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 5a60c0708b239123444f080d00df589428378a57..8347e93ab3772b0addb242ff9fae3704cfa33133 100644 (file)
--- 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 5f9e7eae528a308bf8ae1d9dd08eae01ca886a75..6e726bf961cd00bf4eef74acb93457425d3a826e 100644 (file)
--- 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) {
                                        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) {
+                                       /* 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 6b740240eed3b3cbaa7e405adfe24d43313d1ecc..ac7ea37f20db3fb324cfbdfa50b8f99e51716458 100644 (file)
--- 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,
@@ -2451,11 +2452,14 @@ int parse_server(const char *file, int linenum, char **args, struct proxy *curpr
                                        if (!strcmp(p, "allow-dup-ip")) {
                                                newsrv->dns_opts.accept_duplicate_ip = 1;
                                        }
+                                       else if (!strcmp(p, "ignore-weight")) {
+                                               newsrv->dns_opts.ignore_weight = 1;
+                                       }
                                        else if (!strcmp(p, "prevent-dup-ip")) {
                                                newsrv->dns_opts.accept_duplicate_ip = 0;
                                        }
                                        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;