Make File Transfer Storage Size Configurable

[pzl]

What is the problem this PR solves?

Adds a configuration parameter to fleet server for the maximum size of transferred files via actions

How does this PR solve the problem?

Hard coded limit (100MiB previously) is now a config.

Default is also changed to be unlimited. The file transfer feature launched with very conservative limits on request rates and file sizes. File size itself is primarily an impact on Elasticsearch at rest, at does not effect fleet server, aside from the time to transfer the bytes. Requests are still chunked, chunk size is not changing.

Design Checklist

• I have ensured my design is stateless and will work when multiple fleet-server instances are behind a load balancer.
• I have or intend to scale test my changes, ensuring it will work reliably with 100K+ agents connected.
• I have included fail safe mechanisms to limit the load on fleet-server: rate limiting, circuit breakers, caching, load shedding, etc.

Checklist

• 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/fragments using the changelog tool

[prodsecmachine]

✅ Snyk checks have passed. No issues have been found so far.

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✅	Open Source Security	0	0	0	0	0 issues

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[mergify]

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

• backport-./d./d is the label to automatically backport to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
1 Fixed issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[kaanyalti]

Suggested change

	#pr: https://github.com/owner/repo/1234
	pr: https://github.com/elastic/fleet-server/pull/5478

[ebeahan]

@pzl do you plan to continue work on this PR? If not, I'll plan to close, and you can reopen/recreate when ready to work on it again.

[pzl]

continue work on this PR?

Thanks @ebeahan , we're actually picking this back up now!

Seems like where this left off, was discussion around what type the storage size variable should be, and meanings on edge case numbers (0, negative values), for some concept of "unlimited".

@ycombinator @nkvoll @pchila Can we reach a consensus on what we want that to be?

[ycombinator]

continue work on this PR?

Thanks @ebeahan , we're actually picking this back up now!

Seems like where this left off, was discussion around what type the storage size variable should be, and meanings on edge case numbers (0, negative values), for some concept of "unlimited".

@ycombinator @nkvoll @pchila Can we reach a consensus on what we want that to be?

Apologies for missing this ping (thanks @ebeahan). I think we're pretty close / aligned; here's my take: #5478 (comment)

[nkvoll]

I'm on board with what @ycombinator wrote above, that makes sense to me 👍

[pchila]

continue work on this PR?

Thanks @ebeahan , we're actually picking this back up now!
Seems like where this left off, was discussion around what type the storage size variable should be, and meanings on edge case numbers (0, negative values), for some concept of "unlimited".
@ycombinator @nkvoll @pchila Can we reach a consensus on what we want that to be?

Apologies for missing this ping (thanks @ebeahan). I think we're pretty close / aligned; here's my take: #5478 (comment)

@ycombinator proposal works for me as well 👍

[pzl]

Thanks all, made the change so that nil is unlimited, 0 is disabled feature, and a stated value is the limit, and its a uint so no negatives. Ready for another look-over

cc @ycombinator @pchila @nkvoll