Support format in out_cloudwatch_logs

[wills-feng]

Problem

The format is not recognized in out_cloudwatch_logs. Is there a common case to format output before sending to cloudwatch?

logs in cloudwatch: "message":"Plain logs" expected only keep value(single_value format): "Plain logs"

...

Steps to replicate

Provide example config and message

Expected Behavior or What you need to ask

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Using Fluentd and CloudWatchLogs plugin versions

• OS version
• Bare Metal or within Docker or Kubernetes or others?
• Fluentd v0.12 or v0.14/v1.0
  • paste result of fluentd --version or td-agent --version
• Dependent gem versions
  • paste boot log of fluentd or td-agent
  • paste result of fluent-gem list, td-agent-gem list or your Gemfile.lock

[cosmo0920]

We didn't support arbitrary format on out_cloudwatch_logs just supported JSON encoded style. I've heard it for the first time.

[cosmo0920]

fluent-plugin-cloudwatch-logs v0.12.0 can handle <format> section on its configuration:

<match **>
  @type cloudwatch_logs
  # ... Some stuff
  <format>
    @type single_value
    message_key message
  </format>
</match>