How to remove unicode in fluentd tail/s3 plugin

Question

I have fluentd configuration with source as tail type and destination as aws s3. I could able store the logs in S3.

we have enabled coloring in the application logs, based on log levels in winston logger, but while storing in S3 I'm getting the unicode value for colors like \u001b[34mdebug\u001b[39m. Same happening for special characters also(\u003c for >)

Fluentd Config
--------------
    <source>
      @type tail
      path /var/log/containers/abc-*.log
      pos_file /var/log/abc.log.pos
      tag abc.**
      <parse>
        @type none
      </parse>
      read_from_head true
    </source>
    
    <match abc.**>
       @type s3
    
       aws_key_id "#{ENV['AWS_ACCESS_KEY']}"
       aws_sec_key "#{ENV['AWS_SECRET_ACCESS_KEY']}"
       s3_bucket "#{ENV['S3_LOGS_BUCKET_NAME']}"
       s3_region "#{ENV['S3_LOGS_BUCKET_REGION']}"
       path "#{ENV['S3_LOGS_BUCKET_PREFIX']}"
       s3_object_key_format %{path}/abc/%Y%m%d/%{index}.json
    
       buffer_chunk_limit 20m
       buffer_path /var/log/fluentd-buffer
       store_as json
       flush_interval 600s
       time_slice_format %Y/%m/%d
       utc
    
       <format>
          @type single_value
       </format>
    
       <instance_profile_credentials>
         ip_address 169.254.169.254
         port       80
       </instance_profile_credentials>
    </match>

Current Log stored in S3:

{"log":"2021-04-10T12:34:51.050Z - \u001b[34mdebug\u001b[39m: \u003e\u003e\u003e\u003e testlog1 from app \n","stream":"stdout","time":"2021-04-10T12:34:51.050571552Z"}
{"log":"2021-04-10T12:34:51.067Z - \u001b[34mdebug\u001b[39m: \u003c\u003c\u003c\u003c testlog2 from app\n","stream":"stdout","time":"2021-04-10T12:34:51.068105637Z"}

Expected

{"log":"2021-04-10T12:34:51.050Z - debug: <<<< exec start from app \n","stream":"stdout","time":"2021-04-10T12:34:51.050571552Z"}
{"log":"2021-04-10T12:34:51.067Z - debug: <<<< exec end from app\n","stream":"stdout","time":"2021-04-10T12:34:51.068105637Z"}

Need help on how to print original values.

Answer 1

Try fluentd record_transformer filter plugin like this:

<filter abc.**>
  @type record_transformer
  enable_ruby true
  <record>
    message ${ record["message"].gsub(/(\\u\d+b\[\d+m)|(\\u\d+e)/, '') }
  </record>
</filter>