Formatting unicorn logs in json format for $stderr

[Cenon Del Rosario]

Hi,

I am using rails 3.2.22 / ruby 2.1.8 and am trying to reformat the
unicorn log output from stderr into json format and have had partial
success.

I have a basic json formatter:
class JsonLogFormatter < Logger::Formatter
  def call(severity, datetime, progname, msg)
    log_msg = {
      time: "#{datetime}",
      severity: "#{severity}",
      source: "#{progname}"
    }
    msg.is_a?(Hash) ? log_msg.merge!(msg) : log_msg.merge!(message: "#{msg}")
    "#{log_msg.to_json}\n"
  end
end

I have this in my unicorn config:
Logger.new($stderr).tap do |newlgr|
  newlgr.formatter = JsonLogFormatter.new
end

I have this in my application.rb:
Logger.new(STDOUT).tap do |logr|
  JsonLogFormatter.new.tap do |frmtr|
    logr.formatter = frmtr
    Rails.logger = config.logger = logr
  end
end

For the most part it works and I get the stdout and stderr in json but
I also see some other non-json formatted messages, for example:
{"time":"2021-07-06 17:14:01
+1000","severity":"INFO","source":"","message":"Started GET \"/admin\"
for 127.0.0.1 at 2021-07-06 17:14:01 +1000"}
127.0.0.1 - - [06/Jul/2021 17:14:01] "GET /admin HTTP/1.1" 301 102 0.4243

It seems that rails logs are working and then the unicorn process
itself is outputting its own logs because I can see duplicates of the
same log message one in json and the other in plain text.

Just want to know if there is a way to get this working consistently?

Thank you,
Cenon Del Rosario

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