Backport PR #16906 to 8.x: Add %{{TIME_NOW}} pattern for sprintf

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Backport PR #16906 to 8.x branch, original message:

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Release notes

Add support of %{{TIME_NOW}} syntax to sprinf format to generate a new current timestamp

What does this PR do?

This commit added %{{TIME_NOW}} syntax to event.sprintf() to generate a fresh timestamp as string

Example

input {
    heartbeat {
      add_field => { "heartbeat_time" => "%{{TIME_NOW}}" }
    }
}
filter {
    mutate {
      add_field => { "mutate_time" => "%{{TIME_NOW}}" }
    }
}

It gives two different timestamps.

Why is it important/What is the impact to the user?

When the incoming event has value in @timestamp, eg. event from agent, Logstash use the provided value instead of generating a new timestamp. Prior to the change, there is no way to force a new timestamp to generate during the execution of input plugins.

Previously, users often generate timestamp with ruby-filter code => "event.set('ruby_time', Time.now());", but this approach requires events to pass through PQ before the timestamp was assigned. It is not a good indicator of when the event actually arrived in Logstash.

With this change, all input and filter plugins can generate new timestamps

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Closes support custom setting of the name of timestamp field #15701

Use cases

Screenshots

Logs

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Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

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