api: support hot reload of registry authentication

[imeoer]

Overview

Add HTTP API endpoints to update and query daemon configuration at
runtime without restarting nydusd. This is particularly useful for
refreshing registry credentials when tokens expire.

Key changes:

• Add GET/PUT /api/v1/config endpoints for configuration management
• Add config module in utils for centralized configuration updates
• Add smoke test cases for hot reload configuration API
• Update documentation with hot reload usage examples

Related Issues

containerd/nydus-snapshotter#690

Change Details

Please describe your changes in detail:

Test Results

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Change Type

Please select the type of change your pull request relates to:

• Bug Fix
• Feature Addition
• Documentation Update
• Code Refactoring
• Performance Improvement
• Other (please describe)

Self-Checklist

Before submitting a pull request, please ensure you have completed the following:

• I have run a code style check and addressed any warnings/errors.
• I have added appropriate comments to my code (if applicable).
• I have updated the documentation (if applicable).
• I have written appropriate unit tests.

[codecov]

Codecov Report

❌ Patch coverage is 78.05486% with 88 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.72%. Comparing base (2e78348) to head (25bb400).

Files with missing lines	Patch %	Lines
api/src/http_endpoint_v1.rs	0.00%	19 Missing ⚠️
storage/src/backend/registry.rs	37.93%	18 Missing ⚠️
src/bin/nydusd/api_server_glue.rs	0.00%	16 Missing ⚠️
storage/src/factory.rs	18.75%	10 Missing and 3 partials ⚠️
rafs/src/fs.rs	52.94%	7 Missing and 1 partial ⚠️
utils/src/config.rs	98.61%	4 Missing ⚠️
src/bin/nydus-image/main.rs	0.00%	3 Missing ⚠️
storage/src/device.rs	62.50%	2 Missing and 1 partial ⚠️
service/src/fs_cache.rs	0.00%	2 Missing ⚠️
rafs/src/metadata/mod.rs	0.00%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1864      +/-   ##
==========================================
+ Coverage   56.53%   56.72%   +0.18%     
==========================================
  Files         199      200       +1     
  Lines       52094    52438     +344     
  Branches    44897    45241     +344     
==========================================
+ Hits        29453    29745     +292     
- Misses      21156    21208      +52     
  Partials     1485     1485              

Files with missing lines	Coverage Δ
api/src/http.rs	0.00% <ø> (ø)
api/src/http_handler.rs	53.08% <ø> (ø)
service/src/blob_cache.rs	82.71% <100.00%> (ø)
storage/src/cache/filecache/mod.rs	66.43% <ø> (ø)
storage/src/cache/fscache/mod.rs	74.46% <ø> (ø)
utils/src/lib.rs	98.78% <ø> (ø)
rafs/src/metadata/mod.rs	68.15% <0.00%> (ø)
service/src/fs_service.rs	38.86% <0.00%> (ø)
service/src/fs_cache.rs	28.09% <0.00%> (-0.05%)	⬇️
src/bin/nydus-image/main.rs	0.52% <0.00%> (ø)
... and 7 more

... and 1 file with indirect coverage changes

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[Fricounet]

LGTM in terms of doing what we need for the mentioned issue. I'm not a big rust expert though so take my review with a pinch of salt.
Nice documentation though!

[Zephyrcf]

LGTM!

[BraveY]

It looks like the id parameter now represents a mountpoint ID rather than a blob ID.

[imeoer]

Thanks, let me check this, the blob ID seems to be useless, it should be used as a mountpoint.

[BraveY]

Because this id is no longer blobdid, the corresponding previous read and write statistics for blobid level no longer exist, this behavior change is very large, I think we need to consider adding a mountpoint id as a parameter, instead of directly changing the original blobid to mountpointid.