Allow PKCS8 EC private keys to be loaded

Author: tsaarni

CHANGELOG.md

@@ -1,3 +1,6 @@
+## Unreleased
+  - Support loading of PKCS8 EC private keys.
+
 ## 3.0.5
   - Docs: Set the default_codec doc attribute.
 
@@ -37,4 +40,3 @@
  - Plugins were updated to follow the new shutdown semantic, this mainly allows Logstash to instruct input plugins to terminate gracefully,
    instead of using Thread.raise on the plugins' threads. Ref: https://github.com/elastic/logstash/pull/3895
  - Dependency on logstash-core update to 2.0
-

lib/logstash/outputs/syslog.rb

@@ -227,7 +227,7 @@ def setup_ssl
     require "openssl"
     ssl_context = OpenSSL::SSL::SSLContext.new
     ssl_context.cert = OpenSSL::X509::Certificate.new(File.read(@ssl_cert))
-    ssl_context.key = OpenSSL::PKey::RSA.new(File.read(@ssl_key),@ssl_key_passphrase)
+    ssl_context.key = OpenSSL::PKey::read(File.read(@ssl_key),@ssl_key_passphrase)
     if @ssl_verify
       cert_store = OpenSSL::X509::Store.new
       # Load the system default certificate path to the store