feat: support disabling cloud handling of c8y_Restart operation

[reubenmiller]

Proposed changes

Support new tedge configuration (c8y.enable.device_restart) to disable the handling of the the c8y_Restart operation from Cumulocity.

Other Cumulocity cloud operations already support this mechanism, so the PR just aligns the c8y_Restart with the other cloud operation handlers.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

#3939

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
• I ran just format as mentioned in CODING_GUIDELINES
• I used just check as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[reubenmiller]

I'm not sure whether we should use device_restart or just restart. I opted for a more explicit approach given that some time in the future we'll probably have a "service_restart" command.

[codecov]

Codecov Report

❌ Patch coverage is 58.82353% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/extensions/c8y_mapper_ext/src/converter.rs	37.50%	4 Missing and 1 partial ⚠️
crates/extensions/c8y_mapper_ext/src/config.rs	0.00%	1 Missing ⚠️
...xtensions/c8y_mapper_ext/src/operations/handler.rs	83.33%	0 Missing and 1 partial ⚠️

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[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
823	0	3	823	100	2h50m54.745683s

[jarhodes314]

Does a user need to do both these actions to disable the operation, or is deleting the file just done so we can verify it doesn't reappear after restarting the mapper?

[reubenmiller]

Yes I think the file still needs to be deleted if the tedge-mapper-c8y service has already been started (with the setting on)...though I didn't verify this, so maybe I'm wrong.

[reubenmiller]

I just confirmed that once the c8y_Restart file is created, then the user has to manually remove it as disabling the feature does not affect the supported operations list that is sent to Cumulocity. However the mapper won't react to the operation if it is sent to the cloud.

We could delete the operation if present on startup though. Previously we avoided this as we thought that people might want to customize the operation handler (e.g. create the file themselves), however I don't think anyone is doing this now that we can customize the tedge-agent workflows instead.

The code shows that there is only an "add_operation" function, and nothing to remove an already existing one.

pub async fn add_operation(

[albinsuresh]

LGTM. For the sake of completeness, shouldn't we do the same for software update operation as well?

[rina23q]

Looks good. I just found a trivial thing that can be better.