Httpd returning 503 Service Unavailable with mod_proxy for Tomcat 8
(Answered by the OP in a question edit. Converted to a community wiki answer. See Question with no answers, but issue solved in the comments (or extended in chat) )
The OP wrote:
The answer is here: http://sysadminsjourney.com/content/2010/02/01/apache-modproxy-error-13permission-denied-error-rhel/
Which is a link to a blog that explains:
SELinux on RHEL/CentOS by default ships so that httpd processes cannot initiate outbound connections, which is just what mod_proxy attempts to do.
If this is the problem, it can be solved by running:
/usr/sbin/setsebool -P httpd_can_network_connect 1
And for a more definitive source of information, see https://wiki.apache.org/httpd/13PermissionDenied
Resolve issue Immediate, It's related to internal security
We, SnippetBucket.com working for enterprise linux RedHat, found httpd server don't allow proxy to run, neither localhost or 127.0.0.1, nor any other external domain.
As investigate in server log found
[error] (13)Permission denied: proxy: AJP: attempt to connect to 10.x.x.x:8069 (virtualhost.virtualdomain.com) failed
Audit log found similar port issue
type=AVC msg=audit(1265039669.305:14): avc: denied { name_connect } for pid=4343 comm="httpd" dest=8069 scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:object_r:port_t:s0 tclass=tcp_socket
Due to internal default security of linux, this cause, now to fix (temporary)
/usr/sbin/setsebool httpd_can_network_connect 1
Resolve Permanent Issue
/usr/sbin/setsebool -P httpd_can_network_connect 1