Logstash http output plugin 6.0 ssl issue

[suresh_subbaiah]

Hi,
We are migrating from logstash 2.x to logstash 6.0 with http output plugin. Its a secure request we are making from logstash however we are getting the below error with the latest version.

[2017-11-28T06:35:59,558][ERROR][logstash.outputs.http ] [HTTP Output Failure] Could not fetch URL {:url=>"https://xx.xxx.xxx.xxx:5061/evmon/tenant/platform/service/platform/instance/logging-monitoring/host/866cd7dccc6a?prefix=logstash-graphite.", :method=>:post, :body=>"{\"events.count\":\"457728\",\"events.rate_1m\":\"6230.636748769693\",\"events.rate_5m\":\"3668.5510144327163\",\"events.rate_15m\":\"3064.8561366704157\"}", :headers=>{"Content-Type"=>"application/json"}, :message=>"PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target", :class=>"Manticore::ClientProtocolException", :backtrace=>nil, :will_retry=>true}

logstash 6.0 http output conf

output
{
                http
                {
                        content_type => "application/json"
                        format => "json"
                        http_method => "post"
                        url => "https://xx.xxx.xxx.xxx:5061/evmon/tenant/platform/service/platform/instance/logging-monitoring/host/866cd7dccc6a?prefix=logstash-graphite."
                        #verify_ssl => false
                        #ssl_certificate_validation => false
                        truststore => "/usr/share/logstash/pipeline/ssl/cacerts"
                        truststore_password => "changeit"
                        mapping => [ "events.count", "%{[events][count]}", "events.rate_1m", "%{[events][rate_1m]}", "events.rate_5m", "%{[events][rate_5m]}", "events.rate_15m", "%{[events][rate_15m]}" ]
                }
}

logstash 2.x conf

output
    {
                    http
                    {
                            content_type => "application/json"
                            format => "json"
                            http_method => "post"
                            url => "https://xx.xxx.xxx.xxx:5061/evmon/tenant/platform/service/platform/instance/logging-monitoring/host/866cd7dccc6a?prefix=logstash-graphite."
                            verify_ssl => false
                            ssl_certificate_validation => false
                            truststore => "/usr/share/logstash/pipeline/ssl/cacerts"
                            truststore_password => "changeit"
                            mapping => [ "events.count", "%{[events][count]}", "events.rate_1m", "%{[events][rate_1m]}", "events.rate_5m", "%{[events][rate_5m]}", "events.rate_15m", "%{[events][rate_15m]}" ]
                    }
    }

this is a working configuration, however in latest version verify_ssl and ssl_certificate_validation is removed.

Could you please point what is missing and what needs to be done.
Note: URL is protected by certificate(ssl ssl_protocols TLSv1.2;) in Loadbalancer.