apache-frontend: add possibility to change frontend software release through parameter

software/apache-frontend/README.apache_frontend.txt

@@ -20,17 +20,19 @@ Apache frontend is available in 3 software types:
 About replicate frontend
 ========================
 
-Slaves of the root instance (type "replicate") are sent as a parameter to requested frontends which will process them. The only difference is that they will then return the « would-be published information » to the root instance instead of publishing it. The root instance will then do a synthesis and publish the information to its slaves. The replicate instance only use 4 type of parameters for itself and will transmit the rest to requested frontends.
+Slaves of the root instance (type "replicate") are sent as a parameter to requested frontends which will process them. The only difference is that they will then return the « would-be published information » to the root instance instead of publishing it. The root instance will then do a synthesis and publish the information to its slaves. The replicate instance only use 5 type of parameters for itself and will transmit the rest to requested frontends.
 These parameters are :
   * "-frontend-type" : the type to deploy frontends with. (default to 2)
   * "-frontend-quantity" : The quantity of frontends to request (default to "default")
   * "-frontend-i-state": The state of frontend i
+  * "-frontend-software-release-url": Software release to be used for frontends, default to the current software release
   * "-sla-i-foo" : where "i" is the number of the concerned frontend (between 1 and "-frontend-quantity") and "foo" a sla parameter.
 ex:
 <parameter id="-frontend-quantity">3</parameter>
 <parameter id="-frontend-type">custom-personal</parameter>
 <parameter id="-frontend-2-state">stopped</parameter>
 <parameter id="-sla-3-computer_guid">COMP-1234</parameter>
+<parameter id="-frontend-software-release-url">http://git.erp5.org/gitweb/slapos.git/blob_plain/refs/tags/slapos-0.183:/software/apache-frontend/software.cfg</parameter>
 will request the third frontend on COMP-1234. All frontends will be of software type "custom-personal". The second frontend will be requested with the state stopped
 
 Note: the way slaves are transformed to a parameter avoid modifying more than 3 lines in the frontend logic.

software/apache-frontend/instance-apache-replicate.cfg.in

@@ -64,7 +64,12 @@ sla-{{ parameter }} = {{ slapparameter_dict.pop( sla_key + parameter ) }}
 [replicate]
 <= slap-connection
 recipe = slapos.cookbook:requestoptional
+{% set frontend_software_url_key = "-frontend-software-release-url" %}
+{% if slapparameter_dict.has_key(frontend_software_url_key) %}
+software-url = {{ slapparameter_dict.pop(frontend_software_url_key) }}
+{% else %}
 software-url = ${slap-connection:software-release-url}
+{% endif %}
 software-type = {{frontend_type}}
 return = private-ipv4 public-ipv4 slave-instance-information-list monitor_url
 config = {{ ' '.join(slapparameter_dict.keys()) + ' ' + slave_list_name }}