Initial version for zip download rework

[varmar05]

Rewrite download zip functionality so it creates a background task for zip construction first and only serves content when ready.

So far this is only prototype with some basic workflow

merginmaps-server   | [ACCESS] 172.18.0.1 GET /v1/project/download/mergin/test format=zip HTTP/1.1 202 50 http://localhost:8080/projects/mergin/test/tree "Mozilla/5.0 (X11; Linux x86_64; rv:137.0) Gecko/20100101 Firefox/137.0" 104532 <8>
celery-worker       | [2025-04-11 11:55:51,044: INFO/ForkPoolWorker-1] Task mergin.sync.tasks.create_project_version_zip[d9d90279-ae16-4afd-bd10-2d79cc719df6] succeeded in 0.13913617400248768s: None

TODO:

• rename endpoint (make it private)
• fix tests
• remove unused download functions and libraries, clean up
• frontend
• optionally move locking from FS to redis [NOT PLANNED]
• update nginx config, make sure buffering settings are correct [:question: ]
• make sure, that cleanup of partial is ok - add to controller safe check if .partial is not update more than 30minutes.

Dashboard

• introducing polling for download zip file in following way:

• sending HEAD request to the server until 200 is not returned, if 200 is returned -> download file

• added loading indicator and disable dowloading
  

• added maximum of 100 retries for download

🔨

• do not download files to js blob, use traditional anchor click (sending path to filesaver.saveFile() method)

[coveralls]

Pull Request Test Coverage Report for Build 14704633098

Details

• 119 of 131 (90.84%) changed or added relevant lines in 10 files are covered.
• 40 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.6%) to 91.705%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
server/mergin/sync/public_api_controller.py	1	2	50.0%
server/mergin/sync/tasks.py	24	29	82.76%
server/mergin/sync/private_api_controller.py	23	29	79.31%

Files with Coverage Reduction	New Missed Lines	%
server/mergin/sync/storages/disk.py	15	81.01%
server/mergin/sync/storages/storage.py	25	44.44%

Totals
Change from base Build 14619150676:	-0.6%
Covered Lines:	6910
Relevant Lines:	7535

---

💛 - Coveralls

[varmar05]

Could you guys also double check we have disabled response buffers on proxy for this endpoint?

[MarcelGeo]

Could you guys also double check we have disabled response buffers on proxy for this endpoint?

@varmar05

I updated no buffer endpoint in nginx.conf. See 3f31b3f. There are 🏂 questions about that:

• there was trailing slash on the end of directive, I think It was not working before (could we check our deployments?)
• there was enabled / trying to enable to X-Accel-Buffering with true. By default it's "yes" - it's not causing bad UX with existing download solution?
• I disabled buffering, but after testing on staging, we could introduce changes

[MarcelGeo]

@varmar05 introduced configurable buffering for x accel in download zip.