[Filebeat] httpjson - Add function to return User-Agent #29453

[legoguy1000]

What does this PR do?

Adds a new value template function for the httpjson input to generate/update the User Agent.

Why is it important?

Some integrations require/prefer certain info to be in the user agent

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
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Closes [Filebeat] httpjson - Add function to return User-Agent #29453

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Logs

[mergify]

This pull request does not have a backport label. Could you fix it @legoguy1000? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 7./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2021-12-26T21:14:54.606+0000

• Duration: 12 min 29 sec

• Commit: 55130a4

❕ Flaky test report

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[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b 29453-useragent upstream/29453-useragent
git merge upstream/master
git push upstream 29453-useragent

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[mergify]

This pull request does not have a backport label. Could you fix it @legoguy1000? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 7./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[legoguy1000]

@andrewkroh can u run the tests and review?

[andrewkroh]

/test

[andrewkroh]

Just a few minor comments. Thanks for adding this.

[andrewkroh]

/test

[andrewkroh]

LGTM 👍

[andrewkroh]

/test