Logstash beats input cant start with ssl enabled

Elastic Stack Logstash
5

SOLUTION:

So the problem was invalid private key. I set up debug log level for logstash in logstash.yml:

log.level: debug

Then, in all debug messages, there was message about invalid private key. At first, this should be mentioned, according to me, in INFO logs. The certificate, as I mentioned above, is valid, but the format of certificate was wrong. So from documentation of input beats:

SSL key to use. NOTE: This key need to be in the PKCS8 format, you can convert it with OpenSSL for more information.

So I change format with:

openssl pkcs8 -topk8 -nocrypt -in instance.key -out instance.key.pkcs8

And change my configuration of input beats:

input {
  beats {
    port => 5000
    ssl => true
    ssl_certificate => "/ssl/instance.crt"
    ssl_key => "/ssl/instance.key.pkcs8"
  }
}

Than it starts to work. Everywhere in cluster (filebeat, elasticsearch) was this cert valid, but for logstash, there must be different format.