ERR Failed to publish events caused by: EOF (no tls)

Elastic Stack Beats
3

Thanks Ruflin, indeed I did look at the other threads on the same subject, and ckecked for deprecated tls and ill-formated yml. But still, I couldn't resolve the problem.
So here's my filebeat.yml :

filebeat:
  prospectors:
    -
      paths:
        - /opt/WSO2/wso2esb/repository/logs/wso2carbon.log
      document_type: log
      fields:
         origin: SECURI_ESB
         category: TECHNIQUE
      ignore_older: 744h
    -
      paths:
        - /opt/WSO2/wso2esb/repository/logs/http_access_*.log
      document_type: log
      fields:
         origin: SECURI_ESB
         category: ACCESS
      ignore_older: 744h
    -
      paths:
        - /opt/WSO2/wso2is/repository/logs/wso2carbon.log
      document_type: log
      fields:
         origin: ESBMET_IS
         category: METIER
      ignore_older: 744h
    -
      paths:
        - /opt/WSO2/wso2is/repository/logs/http_access_*.log
      document_type: log
      fields:
         origin: ESBMET_IS
         category: ACCESS
      ignore_older: 744h
    -
      paths:
        - /opt/WSO2/wso2greg/repository/logs/wso2carbon.log
      document_type: log
      fields:
         origin: SECURI_REGISTRY
         category: METIER
      ignore_older: 744h
    -
      paths:
        - /opt/WSO2/wso2greg/repository/logs/http_access_*.log
      document_type: log
      fields:
         origin: SECURI_REGISTRY
         category: ACCESS
      ignore_older: 744h
    -
      paths:
        - /data/logs/*.log
      document_type: log
      fields:
         origin: ESBTEC_MYSQL
         category: TECHNIQUE
      ignore_older: 744h
    -
      paths:
        - /var/log/rabbitmq/*.log
      document_type: log
      fields:
         origin: HELIOS_RABBITMQ
         category: TECHNIQUE
      ignore_older: 744h
output:
  logstash:
    hosts: ["elk-docker:5044"]
    ssl:
      #insecure: true
      certificate_authorities: ["/etc/pki/tls/certs/logstash-beats.crt"]
logging:
  level: warning
  to_files: true
  to_syslog: false

  files:
    path: /var/log/filebeat
    name: filebeat.log
    rotateeverybytes: 10485760 # = 10MB
    keepfiles: 7

And for the logstash part, 02-beats-input.conf and 30-output.conf :

input {
  beats {
    port => 5044
    ssl => true
    ssl_certificate => "/etc/pki/tls/certs/logstash-beats.crt"
    ssl_key => "/etc/pki/tls/private/logstash-beats.key"
  }
}

output {
  elasticsearch {
    hosts => ["localhost"]
    manage_template => false
    index => "filebeat-%{+YYYY.MM.dd.HH}"
    document_type => "%{[@metadata][type]}"
  }
}

Regards
Laurent