Logstash won’t read 1 line input file (and might miss last line of data in any file)

[itaydvir]

I spent a lot of time on this issue until I found the problem:
Like many people who start using logstash, I have created 1 demo input file with 1 line of data.
When I used stdin() for the same input line, everything worked great. but when tried to read same input line from file, logstash didn't read the data.
I think it's because the single line ends with "EOF" and there is no "\n". so only when added a new empty line at the end logstash was able to read the data.

Here is the discussion thread: https://discuss.elastic.co/t/logstash-wont-read-1-line-input-file-and-might-miss-last-line-of-data-in-any-file/51855

It's a small fix that can save a lot of hours around the globe.

• Version: 2.3.1
• Config File:

input {
     # stdin {}
    file {
      path => "/Users/me/Applications/logstash-2.3.1/examples/json_input.1.log"
      start_position => "beginning"
    }
}
filter {

    json{
        source => "message"
    }

    geoip {
        source => "ip"
        target => "geoip"
    }
}
output {
    stdout { 
        codec => rubydebug 
    }
    elasticsearch { 
        hosts => ["localhost:9200"]
        index => "logstash-app-errors"
    }
}

• Steps to Reproduce: just put in json_input.1.log 1 line of input (without new line at the end)

[guyboertje]

Changes to support this are part of the Event Milling redesign. See this discussion issue
Closing

[suyograo]

@guyboertje Can we improve our docs to add this information to help troubleshooting until this is fixed in the product?

[suyograo]

/cc @dedemorton