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Process multi-level nested escaped JSON strings inside JSON with fluentd

I'm new to fluentd and I would like to parse a multi-level nested escaped JSON strings inside JSON.

My messages look like:

{"log":"HELLO WORLD\n","stream":"stdout","time":"2019-05-23T15:40:54.298531098Z"}

{"log":"{\"appName\":\"adapter\",\"time\":\"2019-05-23T15:40:54.299\",\"message\":\"{\\\"level\\\":\\\"info\\\",\\\"message\\\":\\\"Awaiting Messages from queue...\\\"}\"}\n","stream":"stdout","time":"2019-05-23T15:40:54.2996761Z"}

The first message get parsed correctly but the second one got ignored and I guess it's because of an error in parsing format

Here is my source:

    <source>
      @id fluentd-containers.log
      @type tail
      path /var/log/containers/*.log
      pos_file /var/log/containers.log.pos
      tag raw.kubernetes.*
      read_from_head true
      <parse>
        @type multi_format
        <pattern>
          format json
          time_key time
          time_format %Y-%m-%dT%H:%M:%S.%NZ
        </pattern>
        <pattern>
          format /^(?<time>.+) (?<stream>stdout|stderr) [^ ]* (?<log>.*)$/
          time_format %Y-%m-%dT%H:%M:%S.%N%:z
        </pattern>
      </parse>
    </source>

Here is what I tried:

    <filter **>
      @type parser
      key_name log
      reserve_data true
      remove_key_name_field true
      hash_value_field parsed_log
      <parse>
        @type json
      </parse>
    </filter>

i actually just want to parse this log message:

{
"log":"{\"appName\":\"dedge-adapter\",\"time\":\"2019-05-24T02:39:12.242\",\"message\":\"{\\\"level\\\":\\\"warn\\\",\\\"status\\\":401,\\\"method\\\":\\\"GET\\\",\\\"path\\\":\\\"/api/v1/bookings\\\",\\\"requestId\\\":\\\"782a470b-9d62-43d3-9865-1b67397717d4\\\",\\\"ip\\\":\\\"90.79.204.18\\\",\\\"latency\\\":0.097897,\\\"user-agent\\\":\\\"PostmanRuntime/7.11.0\\\",\\\"message\\\":\\\"Request\\\"}\"}\n",
"stream":"stdout",
"time":"2019-05-24T02:39:12.242383376Z"
}
Solution

  • Do you have multiple format log field? If so, you can use https://github.com/repeatedly/fluent-plugin-multi-format-parser

    <source>
  @type dummy
  tag dummy
  dummy [
    {"log":"HELLO WORLD\n","stream":"stdout","time":"2019-05-23T15:40:54.298531098Z"},
    {"log":"{\"appName\":\"adapter\",\"time\":\"2019-05-23T15:40:54.299\",\"message\":\"{\\\"level\\\":\\\"info\\\",\\\"message\\\":\\\"Awaiting Messages from queue...\\\"}\"}\n","stream":"stdout","time":"2019-05-23T15:40:54.2996761Z"}
  ]
</source>

<filter dummy>
  @type parser
  key_name log
  reserve_data true
  remove_key_name_field true
  <parse>
    @type multi_format
    <pattern>
      format json
    </pattern>
    <pattern>
      format none
    </pattern>
  </parse>
</filter>

<filter dummy>
  @type parser
  key_name message
  reserve_data true
  remove_key_name_field true
  <parse>
    @type multi_format
    <pattern>
      format json
    </pattern>
    <pattern>
      format none
    </pattern>
  </parse>
</filter>

<match dummy>
  @type stdout
</match>

    Output:

    2019-06-03 11:41:13.022468253 +0900 dummy: {"stream":"stdout","time":"2019-05-23T15:40:54.298531098Z","message":"HELLO WORLD\n"}
2019-06-03 11:41:14.024253824 +0900 dummy: {"stream":"stdout","time":"2019-05-23T15:40:54.2996761Z","appName":"adapter","level":"info","message":"Awaiting Messages from queue..."}