MEDIUM: server: allow multi-level server tracking

Now that it is possible to know whether a server is in forced maintenance
or inherits its maintenance status from another one, it is possible to
allow server tracking at more than one level. We still provide a loop
detection however.

Note that for the stats it's a bit trickier since we have to report the
check state which corresponds to the state of the server at the end of
the chain.

diff --git a/doc/configuration.txt b/doc/configuration.txt
index a5ec7328cd9596f38d520a9d1810a7d5c40d6bb6..b81b78ddfcb22a23b75cd21edebc47158f36aefb 100644 (file)
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -8999,10 +8999,10 @@ ssl
   Supported in default-server: No
 
 track [<proxy>/]<server>
-  This option enables ability to set the current state of the server by
-  tracking another one. Only a server with checks enabled can be tracked
-  so it is not possible for example to track a server that tracks another
-  one. If <proxy> is omitted the current one is used. If disable-on-404 is
+  This option enables ability to set the current state of the server by tracking
+  another one. It is possible to track a server which itself tracks another
+  server, provided that at the end of the chain, a server has health checks
+  enabled. If <proxy> is omitted the current one is used. If disable-on-404 is
   used, it has to be enabled on both proxies.
 
   Supported in default-server: No

diff --git a/src/cfgparse.c b/src/cfgparse.c
index 08168a1713f6b2be55f63b5b3f25703eee83e90f..0a32df482c4d964685ab980df0ffed3f206f3134 100644 (file)
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -6563,7 +6563,7 @@ out_uri_auth_compat:
 
                        if (newsrv->trackit) {
                                struct proxy *px;
-                               struct server *srv;
+                               struct server *srv, *loop;
                                char *pname, *sname;
 
                                pname = newsrv->trackit;
@@ -6597,11 +6597,24 @@ out_uri_auth_compat:
                                        goto next_srv;
                                }
 
-                               if (!(srv->check.state & CHK_ST_CONFIGURED)) {
+                               if (!(srv->check.state & CHK_ST_CONFIGURED) &&
+                                   !(srv->agent.state & CHK_ST_CONFIGURED) &&
+                                   !srv->track && !srv->trackit) {
                                        Alert("config : %s '%s', server '%s': unable to use %s/%s for "
-                                               "tracking as it does not have checks enabled.\n",
-                                               proxy_type_str(curproxy), curproxy->id,
-                                               newsrv->id, px->id, srv->id);
+                                             "tracking as it does not have any check nor agent enabled.\n",
+                                             proxy_type_str(curproxy), curproxy->id,
+                                             newsrv->id, px->id, srv->id);
+                                       cfgerr++;
+                                       goto next_srv;
+                               }
+
+                               for (loop = srv->track; loop && loop != newsrv; loop = loop->track);
+
+                               if (loop) {
+                                       Alert("config : %s '%s', server '%s': unable to track %s/%s as it "
+                                             "belongs to a tracking chain looping back to %s/%s.\n",
+                                             proxy_type_str(curproxy), curproxy->id,
+                                             newsrv->id, px->id, srv->id, px->id, loop->id);
                                        cfgerr++;
                                        goto next_srv;
                                }

diff --git a/src/dumpstats.c b/src/dumpstats.c
index d0cd63261071ef353a939a419c8392c14947adfa..4d56e25c3315cb7e770a71f9e5996a1826ad006b 100644 (file)
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -2737,11 +2737,19 @@ static int stats_dump_li_stats(struct stream_interface *si, struct proxy *px, st
 static int stats_dump_sv_stats(struct stream_interface *si, struct proxy *px, int flags, struct server *sv, int state)
 {
        struct appctx *appctx = __objt_appctx(si->end);
-       struct server *ref = sv->track ? sv->track : sv;
+       struct server *via, *ref;
        char str[INET6_ADDRSTRLEN];
        struct chunk src;
        int i;
 
+       /* we have "via" which is the tracked server as described in the configuration,
+        * and "ref" which is the checked server and the end of the chain.
+        */
+       via = sv->track ? sv->track : sv;
+       ref = via;
+       while (ref->track)
+               ref = ref->track;
+
        if (appctx->ctx.stats.flags & STAT_FMT_HTML) {
                static char *srv_hlt_st[9] = {
                        "DOWN",
@@ -2950,7 +2958,7 @@ static int stats_dump_sv_stats(struct stream_interface *si, struct proxy *px, in
                        /* tracking a server */
                        chunk_appendf(&trash,
                                      "<td class=ac colspan=3><a class=lfsb href=\"#%s/%s\">via %s/%s</a></td>",
-                                     ref->proxy->id, ref->id, ref->proxy->id, ref->id);
+                                     via->proxy->id, via->id, via->proxy->id, via->id);
                }
                else
                        chunk_appendf(&trash, "<td colspan=3></td>");
@@ -3000,7 +3008,7 @@ static int stats_dump_sv_stats(struct stream_interface *si, struct proxy *px, in
 
                /* status */
                if (sv->admin & SRV_ADMF_IMAINT)
-                       chunk_appendf(&trash, "MAINT (via %s/%s),", ref->proxy->id, ref->id);
+                       chunk_appendf(&trash, "MAINT (via %s/%s),", via->proxy->id, via->id);
                else if (sv->admin & SRV_ADMF_MAINT)
                        chunk_appendf(&trash, "MAINT,");
                else
@@ -3582,10 +3590,9 @@ static int stats_dump_proxy_to_buffer(struct stream_interface *si, struct proxy
                                        continue;
                        }
 
-                       if (sv->track)
-                               svs = sv->track;
-                       else
-                               svs = sv;
+                       svs = sv;
+                       while (svs->track)
+                               svs = svs->track;
 
                        /* FIXME: produce some small strings for "UP/DOWN x/y &#xxxx;" */
                        if (!(svs->check.state & CHK_ST_ENABLED))

diff --git a/src/server.c b/src/server.c
index f0fb0a76dc771b92174124e27e16ee36a3420dd1..53e20bf71e97388b9cee84e13a78038188d9504b 100644 (file)
--- a/src/server.c
+++ b/src/server.c
@@ -359,12 +359,16 @@ void srv_adm_set_ready(struct server *s, enum srv_admin mode)
                check->health = check->rise; /* start OK but check immediately */
        }
 
+       srv = s;
+       while (srv->track)
+               srv = srv->track;
+
        if ((!s->track &&
             (!(s->agent.state & CHK_ST_ENABLED) || (s->agent.health >= s->agent.rise)) &&
             (!(s->check.state & CHK_ST_ENABLED) || (s->check.health >= s->check.rise))) ||
            (s->track &&
-            (!(s->track->agent.state & CHK_ST_ENABLED) || (s->track->agent.health >= s->track->agent.rise)) &&
-            (!(s->track->check.state & CHK_ST_ENABLED) || (s->track->check.health >= s->track->check.rise)))) {
+            (!(srv->agent.state & CHK_ST_ENABLED) || (srv->agent.health >= srv->agent.rise)) &&
+            (!(srv->check.state & CHK_ST_ENABLED) || (srv->check.health >= srv->check.rise)))) {
 
                if (s->proxy->srv_bck == 0 && s->proxy->srv_act == 0) {
                        if (s->proxy->last_change < now.tv_sec)         // ignore negative times