Added Haproxy global tunables

Max number of connection may be set up, as well as major tunables
may be added as the variables.

Change-Id: I5b333b79680d81b030810a7e94e3cc4bfe724649

defaults/main.yml

@@ -73,3 +73,17 @@ haproxy_hatop_download_url: "https://storage.googleapis.com/google-code-archive-
 
 ## haproxy default timeouts
 haproxy_http_request_timeout: "5s"
+
+## haproxy tuning params
+haproxy_maxconn: 4096
+
+# Parameters below should only be specified if necessary, defaults are programmed in the template
+#haproxy_tuning_params:
+#  nbproc: 1
+#  bufsize: 384000
+#  chksize: 16384
+#  comp_maxlevel: 1
+#  http_maxhdr: 101
+#  http_maxaccept: 64
+#  ssl_cachesize: 20000
+#  ssl_lifetime: 300

releasenotes/notes/implement_tuning_params-e627c774c0d0c9d2.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - Haproxy-server role allows to set up tunable parameters.
+    For doing that it is necessary to set up a dictionary of options in the
+    config files, mentioning those which have to be changed (defaults for the
+    remaining ones are programmed in the template). Also "maxconn" global option
+    made to be tunable.

templates/haproxy.cfg.j2

@@ -7,8 +7,17 @@ global
         user haproxy
         group haproxy
         daemon
-        maxconn 4096
-        tune.bufsize 384000
+        maxconn {{ haproxy_maxconn }}
+{% if haproxy_tuning_params is defined %}
+        nbproc {{ haproxy_tuning_params.nbproc | default('1') }}
+        tune.bufsize {{ haproxy_tuning_params.bufsize | default('384000') }}
+        tune.chksize {{ haproxy_tuning_params.chksize | default('16384') }}
+        tune.comp.maxlevel {{ haproxy_tuning_params.comp_maxlevel | default('1') }}
+        tune.http.maxhdr {{ haproxy_tuning_params.http_maxhdr | default('101') }}
+        tune.http.maxaccept{{ haproxy_tuning_params.http_maxaccept | default('64') }}
+        tune.ssl.cachesize {{ haproxy_tuning_params.ssl_cachesize | default('20000') }}
+        tune.ssl.lifetime {{ haproxy_tuning_params.ssl_lifetime | default('300') }}
+{% endif %}
         stats socket /var/run/haproxy.stat level admin mode 600
         {% if haproxy_ssl | bool %}
         ssl-default-bind-options {{ haproxy_ssl_bind_options }}