Embedded Tomcat container binds port before application is completely started #55
Description
Currently, when an application is starting up, the embedded Tomcat container binds to its port before the application has finished starting. To see this in action, attempt to start a controller that sleeps in a static block. Something like the following:
Controller
class Example {
static {
Thread.sleep(30*1000)
}
@RequestMapping("/")
@ResponseBody
public String controller(HttpEntity<String> requestEntity) {
return "Hello World!"
}
}When you run spring run app.groovy, you'll see the console stall before the application has stated completely. However, if you attempt to curl http://localhost:8080, curl will also stall because the port is bound and while no response has been returned, a socket connection can be completed. An alternative test is to telnet localhost 8080 and see if a connection can be made.
This is problematic in Cloud Foundry as the HealthManager determines when an application has started by attempted a socket connection to it's provided port. Whether the application is running behind the scenes isn't actually checked, so a false-positive started can be returned.
The intended behavior should be that when the console is stalled as described above, curl should return curl: (7) couldn't connect to host indicating that the port hasn't even been bound to yet. This is typically set in the Tomcat configuration using bindOnInit. I believe that there is a programmatic equivalent to this configuration parameter.