feat: add labels field to kibana synthetics monitor resource

[RJiraya]

Pull Request: Add Labels Field to Kibana Synthetics Monitor Resource

Summary

This PR adds support for the labels field to the Kibana synthetics monitor terraform resource, allowing users to associate key-value pairs with monitors for filtering and grouping purposes.

Changes Made

API Layer Updates

• File: libs/go-kibana-rest/kbapi/api.kibana_synthetics.go
• Added Labels map[string]string field to SyntheticsMonitorConfig struct with JSON tag "labels,omitempty"
• Added Labels map[string]string field to SyntheticsMonitor struct with JSON tag "labels,omitempty"

Terraform Schema Updates

• File: internal/kibana/synthetics/schema.go
• Added Labels types.Map field to tfModelV0 struct with tfsdk tag "labels"
• Added labels field as schema.MapAttribute with types.StringType elements to monitorConfigSchema
• Added helper functions:
  • MapStringValue(): Converts map[string]string to types.Map
  • ValueStringMap(): Converts types.Map to map[string]string
• Updated conversion functions:
  • Modified toModelV0() to handle labels from API response
  • Modified toSyntheticsMonitorConfig() to include labels in API requests

Documentation Updates

• File: docs/resources/kibana_synthetics_monitor.md
• Added labels field to the optional parameters list with description
• Added example usage showing labels with environment and team values

Usage Example

resource "elasticstack_kibana_synthetics_monitor" "my_monitor" {
  name      = "Example http monitor"
  space_id  = "default"
  schedule  = 10
  locations = ["us_west"]
  enabled   = false
  tags      = ["tag"]
  labels = {
    environment = "production"
    team        = "platform"
    service     = "web-app"
  }
  alert = {
    status = {
      enabled = true
    }
    tls = {
      enabled = false
    }
  }
  service_name = "example apm service"
  timeout      = 30
  http = {
    url                     = "http://localhost:8080"
    ssl_verification_mode   = "full"
    ssl_supported_protocols = ["TLSv1.2"]
    max_redirects           = "10"
    mode                    = "all"
    ipv4                    = true
    ipv6                    = true
  }
}

API Compatibility

• Follows the official Kibana Synthetics API specification
• Labels field is optional and backward compatible
• Existing configurations continue to work without modification
• Labels are defined as key-value pairs that can be used for filtering and grouping monitors

Technical Details

Field Definition

• Type: Map of String in Terraform schema
• API Type: map[string]string in Go structs
• JSON Tag: "labels,omitempty" - field is omitted when empty
• Description: "Key-value pairs of labels to associate with the monitor. Labels can be used for filtering and grouping monitors."

Implementation Notes

• The implementation maintains consistency with existing field patterns in the codebase
• Proper null/unknown value handling for Terraform types
• Conversion functions handle empty/null maps gracefully
• No breaking changes to existing functionality

Unit Tests Added

• TestMapStringValue: Tests conversion from map[string]string to types.Map
  • Covers nil maps, empty maps, and populated maps
• TestValueStringMap: Tests conversion from types.Map to map[string]string
  • Covers null maps, unknown maps, empty maps, and populated maps
• TestLabelsFieldConversion: Tests labels field conversion in API response processing
  • Tests nil labels, empty labels, and populated labels scenarios
• TestToSyntheticsMonitorConfig: Tests labels field conversion in API request creation
  • Verifies proper handling of labels in both directions
• Updated existing test cases: All existing monitor type tests updated to include Labels field

Acceptance Tests Added

• File: internal/kibana/synthetics/acc_test.go
• Test Function: TestSyntheticMonitorLabelsResource
• Test Configurations:
  • httpMonitorLabelsConfig: Creates monitor with 3 labels (environment=production, team=platform, service=web-app)
  • httpMonitorLabelsUpdated: Updates label values (environment=staging, team=platform-updated, service=web-app-v2)
  • httpMonitorLabelsRemoved: Removes all labels to test round-trip consistency

Testing Checklist

• Unit tests added and pass
• Unit tests cover all conversion functions (MapStringValue, ValueStringMap)
• Unit tests cover labels field conversion in both directions
• Unit tests cover null, empty, and populated label scenarios
• All existing unit tests updated to include Labels field
• Acceptance tests added and pass
• Backward compatibility verified (Labels field is optional)
• Documentation generation works correctly

Files Modified

1. libs/go-kibana-rest/kbapi/api.kibana_synthetics.go - Added Labels field to API structs
2. internal/kibana/synthetics/schema.go - Added Labels field to Terraform schema and conversion functions
3. internal/kibana/synthetics/schema_test.go - Added comprehensive unit tests for Labels field
4. internal/kibana/synthetics/acc_test.go - Added acceptance tests for Labels field (TestSyntheticMonitorLabelsResource)
5. docs/resources/kibana_synthetics_monitor.md - Updated documentation with Labels field

Pre-submission Checklist

• Code follows project conventions
• Documentation updated with field description
• Usage examples provided
• Backward compatibility maintained
• API specification compliance verified
• Tests added/updated (comprehensive unit tests added)
• Changelog entry

Additional Notes

• The labels field supports any string key-value pairs
• Labels are optional and can be omitted from configuration
• Implementation follows the existing patterns for similar fields like tags
• The feature aligns with Kibana's native labeling capabilities for synthetics monitors

Changelog Entry

### Added
- Added `labels` field to `elasticstack_kibana_synthetics_monitor` resource for associating key-value pairs with monitors ([#1360](https://github.com/elastic/terraform-provider-elasticstack/pull/1360))

[cla-checker-service]

💚 CLA has been signed

[tobio]

Thanks @RJiraya are you able to add an acceptance test step covering the labels attribute and update CHANGELOG.md as well please?

[RJiraya]

@tobio it's updated :)

[tobio]

Love it, ty!