clustering wso2 api manager gateway - wso2

Question

i'm trying to cluster wso2 api manager 1.10 gateway into 3 host using tutorial here : https://docs.wso2.com/display/CLUSTER44x/Clustering+the+Gateway, but some of the steps are confusing.
As i know, wso2 api manager has two transport which is
1.) servlet transport (tomcat) located at port 9443 (https) and 9763 (http) used to serve carbon related service
2.) PTT/NIO transport (axis2) located at port 8243 (https) and 8280 (http) used to serve requests to deployment artifacts.
What i don't understand from the tutorial is :
1.) why should there be a port mapping in the clustering configuration (located in axis2 configuration) of the gateway manager component?
<parameter name="properties">
<property name="backendServerURL" value="https://${hostName}:${httpsPort}/services/"/>
<property name="mgtConsoleURL" value="https://${hostName}:${httpsPort}/"/>
<property name="subDomain" value="mgt"/>
<property name="port.mapping.80" value="9763"/>
<property name="port.mapping.443" value="9443"/>
</parameter>
isn't it already defined in load balancer (nginx) configuration
server {
listen 443;
server_name mgt.am.wso2.com;
ssl on;
ssl_certificate /etc/nginx/ssl/mgt.crt;
ssl_certificate_key /etc/nginx/ssl/mgt.key;
location / {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_read_timeout 5m;
proxy_send_timeout 5m;
proxy_pass https://xxx.xxx.xxx.xx3:9443/;
}
error_log /var/log/nginx/mgt-error.log ;
access_log /var/log/nginx/mgt-access.log;
}
and in tomcat configuration?
<Connector protocol="org.apache.coyote.http11.Http11NioProtocol" port="9763" proxyPort="80" ... />
<Connector protocol="org.apache.coyote.http11.Http11NioProtocol" port="9443" proxyPort="443"/>
2.) Why does the load balancer configuration for gateway worker use the servlet port? shouldn't it be the PTT/NIO port? (since the gateway worker are used to serve requests to deployment artifacts)
upstream wso2.am.com {
sticky cookie JSESSIONID;
server xxx.xxx.xxx.xx4:9763;
server xxx.xxx.xxx.xx5:9763;
}
server {
listen 80;
server_name am.wso2.com;
location / {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_read_timeout 5m;
proxy_send_timeout 5m;
proxy_pass http://wso2.am.com;
}
}
upstream ssl.wso2.am.com {
sticky cookie JSESSIONID;
server xxx.xxx.xxx.xx4:9443;
server xxx.xxx.xxx.xx5:9443;
}
server {
listen 443;
server_name am.wso2.com;
ssl on;
ssl_certificate /etc/nginx/ssl/wrk.crt;
ssl_certificate_key /etc/nginx/ssl/wrk.key;
location / {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_read_timeout 5m;
proxy_send_timeout 5m;
proxy_pass https://ssl.wso2.am.com;
}
}

Answer 1

There are two of transport ports in API Manager, PTT and servlet. When a request comes into the API Manager, it always goes to the default transport which is the PTT/NIO transport.
When the admin services are called (ex: Publishing API), you send a servlet request. If you do not specify the port mapping parameter in the manager node, it would hit the PTT/NIO transport and the request would fail.
Here, it has specified a common example for load balancer config. Your config needs to be changed according to Gateway worker.