PMM-14267 Fix persistence of changed listen ports

[ademidoff]

PMM-14267

Link to the Feature Build: SUBMODULES-4217

This pull request introduces a mechanism for immediate VictoriaMetrics configuration updates when an agent's listen port changes, preventing stale port scraping. It adds a new method to the prometheusService interface, updates the handler logic to detect port changes, and provides comprehensive unit tests for this detection. Additionally, mock implementations and interface definitions across multiple packages are updated to support the new method.

Immediate VictoriaMetrics configuration update on port changes:

• Added ForceConfigurationUpdate(ctx context.Context) error to the prometheusService interface in managed/services/agents/deps.go, managed/services/inventory/deps.go, managed/services/management/deps.go, and managed/services/server/deps.go, along with documentation explaining its purpose for critical updates like port changes. [1] [2] [3] [4]
• Updated agent state change handling in managed/services/agents/handler.go to detect listen port changes using the new checkPortChanged function, and trigger ForceConfigurationUpdate for VictoriaMetrics when a port change is detected. [1] [2] [3] [4]
• Replaced direct agent reloads with models.FindAgentByID for consistency and reliability in agent lookup. [1] [2]

Testing and mocks:

• Added a comprehensive unit test for checkPortChanged in managed/services/agents/handler_test.go, covering edge cases such as agent not found, old port zero, port equality, port difference, and type conversion.
• Updated mock implementations in managed/services/inventory/mock_prometheus_service_test.go, managed/services/management/mock_prometheus_service_test.go, and managed/services/server/mock_prometheus_service_test.go to support the new ForceConfigurationUpdate method. [1] [2] [3]

Dependency and configuration updates:

• Upgraded github.com/DATA-DOG/go-sqlmock dependency from v1.5.0 to v1.5.2 in go.mod for improved testing support.
• Enabled issue-845-fix in .mockery.yaml as per the warning message.
• Removed the go-consistent tool for two major reasons:
  • part of its functionality is already covered by golangci-lint
  • it is inflexible and difficult to configure, for example it can't reliably skip tests, which is annoying

[codecov]

Codecov Report

❌ Patch coverage is 28.00000% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.86%. Comparing base (ae3203a) to head (d8e960e).
⚠️ Report is 18 commits behind head on v3.

Files with missing lines	Patch %	Lines
managed/services/agents/handler.go	36.84%	12 Missing ⚠️
...anaged/services/victoriametrics/victoriametrics.go	0.00%	3 Missing ⚠️
managed/services/vmalert/vmalert.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##               v3    #5007      +/-   ##
==========================================
- Coverage   45.90%   45.86%   -0.05%     
==========================================
  Files         366      367       +1     
  Lines       38438    38552     +114     
==========================================
+ Hits        17646    17680      +34     
- Misses      19093    19172      +79     
- Partials     1699     1700       +1     

Flag	Coverage Δ
admin	17.82% <ø> (ø)
agent	53.52% <ø> (+0.19%)	⬆️
managed	46.45% <28.00%> (-0.15%)	⬇️
vmproxy	72.09% <ø> (ø)

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[ademidoff]

I'm removing the go-consistent tool for two major reasons:

• part of its functionality is already covered by golangci-lint
• it is inflexible and difficult to configure, for example it can't reliably skip tests, which requires workarounds and is simply annoying

[ademidoff]

Refactored in favor of using the model.

[ademidoff]

Fixed a mockery warning.

[maxkondr]

why a separate method is required? Can't port change be handled via RequestConfigurationUpdate?

[ademidoff]

This one is synchronous, and RequestConfigurationUpdate is async. We previously used that one, and it worked well, except in cases where the port number is changed. In such case, we need to synchronously update VM's configuration, otherwise there will be bugs like the one in question.