How do I pretty-print JSON for an email body in logstash?

问题

I have a Logstash configuration that I've been using to forward log messages in emails. It uses json and json_encode to parse and re-encode JSON log messages.

json_encode used to pretty-print the JSON, which made for very nice looking emails. Unfortunately, with recent Logstash upgrades, it no longer pretty prints.

Is there any way I can get a pretty form of the event into a field that I can use for the email bodies? I'm fine with JSON, Ruby debug, or most other human readable formats.

filter {
    if [type] == "bunyan" {
        # Save a copy of the message, in case we need to pretty-print later
        mutate {
            add_field => { "@orig_message" => "%{message}" }
        }

        json {
            source => "message"
            add_tag => "json"
        }
    }

    // other filters that might add an "email" tag

    if "email" in [tags] {
        # pretty-print JSON for the email
        if "json" in [tags] {
            # re-parse the message into a field we can encode
            json {
                source => "@orig_message"
                target => "body"
            }

            # encode the message, but pretty this time
            json_encode {
                source => "body"
                target => "body"
            }
        }

        # escape the body for HTML output
        mutate {
            add_field => { htmlbody => "%{body}" }
        }
        mutate {
            gsub => [
                'htmlbody', '&', '&amp;',
                'htmlbody', '<', '&lt;'
            ]
        }
    }
}

output {
    if "email" in [tags] and "throttled" not in [tags] {
        email {
            options => {
                # config stuff...
            }
            body => "%{body}"
            htmlbody => "
<table>
  <tr><td>host:</td><td>%{host}</td></tr>
  <tr><td>when:</td><td>%{@timestamp}</td></tr>
</table>
<pre>%{htmlbody}</pre>
"
        }
    }
}

回答1:

As said by approxiblue, this issue is caused by logstash's new JSON parser (JrJackson). You can use the old parser as a workaround until pretty-print support is added again. Here is how:

You need to change two lines of the plugin's ruby file. Path should be something like:

LS_HOME/vendor/bundle/jruby/1.9/gems/logstash-filter-json_encode-0.1.5/lib/logstash/filters/json_encode.rb

Change line 5

require "logstash/json"

into

require "json"

And change line 44

event[@target] = LogStash::Json.dump(event[@source])

into

event[@target] = JSON.pretty_generate(event[@source])

That's all. After restarting logstash should pretty-print again.

Supplement:

In case you don't like changing your ruby sources you could also use a ruby filter instead of json_encode:

# encode the message, but pretty this time
ruby  {
    init => "require 'json'"
    code => "event['body'] = JSON.pretty_generate(event['body'])"
}

来源：https://stackoverflow.com/questions/32077228/how-do-i-pretty-print-json-for-an-email-body-in-logstash

标签

json

logstash

logstash-configuration