service: print more error message

[WeiZhang555]

Some error messages were swallowed which makes user confused, for example, for RAFSv6, we need to set blobcache config in localfs.json (following docs tutorial), before modification, the error message indicates nothing:

ERROR [src/bin/nydusd/main.rs:525] Failed in starting daemon: Invalid
argument (os error 22)

After this modification, we get clearer error message:

ERROR [/src/fusedev.rs:595] service mount error: RAFS failed to handle
request, Configure("Rafs v6 must have local blobcache configured")

Relevant Issue (if applicable)

Details

Please describe the details of PullRequest.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[anolis-bot]

@WeiZhang555 , a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/88725

[anolis-bot]

@WeiZhang555 , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		❌ FAIL

Sorry, your test job failed. Please get the details in the link.

[codecov]

Codecov Report

Merging #1388 (880adbb) into master (43c737d) will decrease coverage by 0.26%.
The diff coverage is 0.00%.

❗ Current head 880adbb differs from pull request most recent head b09acfa. Consider uploading reports for the commit b09acfa to get more accurate results

@@            Coverage Diff             @@
##           master    #1388      +/-   ##
==========================================
- Coverage   46.31%   46.05%   -0.26%     
==========================================
  Files         122      122              
  Lines       38071    38077       +6     
  Branches    38071    38077       +6     
==========================================
- Hits        17632    17536      -96     
- Misses      19513    19621     +108     
+ Partials      926      920       -6     

Files Changed	Coverage Δ
service/src/fusedev.rs	0.00% <0.00%> (ø)

... and 8 files with indirect coverage changes

[WeiZhang555]

More details:

Following tutorial: https://github.com/dragonflyoss/image-service/blob/master/docs/tutorial.md#build-nydus-image-from-directory-source

When I tried to start a nydusd with this localfs.json:

{
  "device": {
    "backend": {
      "type": "localfs",
      "config": {
        "dir": "/<YOUR-WORK-PATH>/nydus-image/blobs"
      }
    }
  },
  "mode": "direct"
}

The nydusd errors out with this message:

It saids "Invalid arguments" which confused me a lot, after some debugging, I found that RAFSv6 needs to set blob cache config, e.g.

{
  "device": {
    "backend": {
      "type": "localfs",
      "config": {
        "dir": "/<YOUR-WORK-PATH>/nydus-image/blobs"
      }
    },
    "cache": {
      "type": "blobcache",
      "config": {
        "work_dir": "/var/lib/nydus/cache"
      }
    }
  },
  "mode": "direct"
}

A better error message should tell us the configuration is error, so I just add a little bit new code to reveal the inner error.

Final result:

The docs should be updated too, I'll append another commit.

[anolis-bot]

@WeiZhang555 , the code has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/88755

[anolis-bot]

@WeiZhang555 , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@WeiZhang555 , the code has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/89086

[anolis-bot]

@WeiZhang555 , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[adamqqqplay]

Very detailed analysis, thanks for your work!