Delay server startup

[jameskleeh]

Currently the channel is getting initialized before the acme setup is done and is causing this exception:

00:38:15.311 [nioEventLoopGroup-1-2] WARN  io.netty.channel.ChannelInitializer - Failed to initialize a channel. Closing: [id: 0x6816b54e, L:/10.128.0.3:443 - R:/24.154.202.70:55297]
java.lang.NullPointerException: null
	at io.micronaut.configuration.acme.ssl.DelegatedSslContext.newEngine(DelegatedSslContext.java:79)
	at io.netty.handler.ssl.SslContext.newHandler(SslContext.java:953)
	at io.netty.handler.ssl.SslContext.newHandler(SslContext.java:945)
	at io.micronaut.http.server.netty.NettyHttpServer$NettyHttpServerInitializer.initChannel(NettyHttpServer.java:746)
	at io.micronaut.http.server.netty.NettyHttpServer$NettyHttpServerInitializer.initChannel(NettyHttpServer.java:734)

The refresh task should probably listen to io.micronaut.context.event.StartupEvent and block until its finished

[zendern]

@jameskleeh In regards to listening to StartupEvent over the existing ApplicationStartupEvent found here.

micronaut-acme/acme/src/main/java/io/micronaut/acme/background/AcmeCertRefresherTask.java

Lines 104 to 107 in 295e5f6

	@EventListener
	void onStartup(ApplicationStartupEvent startupEvent) throws AcmeException {
	renewCertIfNeeded();
	}

I believe that would only work in the DNS Challenge type case since it doesn't require the application to actually respond to requests from the ACME server. Both the TLS and HTTP challenge types have endpoints that get setup as part of the application so that the ACME validation steps can be done. Switching to listening to StartupEvent appears to be before those are actually up and running so idk if that is possible but if you have thoughts I'm open to changing it.

[jameskleeh]

@zendern Seems like there is a bunch of work that could be done prior though. Seems like the order can be created, and then do the authorizations in the current event listener