Character encoding problems

Elastic Stack Logstash
4

One thing to note. The codec charset directive is not a "to" operation, it is a "from" operation. In Logstash, the "to" charset is always UTF-8.

Logstash does not have universal charset detection so it needs to know what charset the strings are encoded in to be able to convert them to UTF-8.

When I run your config without the jdbc output I get:

input {
  stdin {
    codec => plain { charset=>"UTF-8" }
  }
}
output {
  stdout { codec => rubydebug }
}

result:

{
      "@version" => "1",
          "host" => "Elastics-MacBook-Pro.local",
    "@timestamp" => 2018-04-05T20:50:16.143Z,
       "message" => "fühlen"
}

From this SO post you could try locale charmap to see what the charset for the vm is, or for a more realistic test the exec input.

input {
  exec {
    command => "locale charmap"
    interval => 3600
  }
}
output {
  stdout { codec => rubydebug }
}