Incorrect Status Displayed for External Services in PMM Inventory

User Impact:

The bug affects the PMM monitoring feature by displaying an incorrect status for external services. This can cause confusion for users and make it difficult for them to determine the actual status of the monitored services.

Steps to Reproduce:

1. Add an external service to PMM.

2. Enter the address and port fields with valid information.

3. Wait for PMM to display the status of the external service.

Actual Result: PMM displays a "failed" status for the external service, even though the exporter may be running and exposing metrics.

Expected Result: PMM should display an "unknown" status for the external service since the external exporter does not know the address and port fields. The monitoring status should be "OK" since PMM can still collect metrics from the exporter.

Bug Description:

The bug occurs when a user adds an external service to PMM and enters valid information in the address and port fields. PMM then displays a "failed" status for the external service, even though the exporter may be running and exposing metrics. This is incorrect since the purpose of the address and port fields is to determine the location of the exporter, and in the case of external exporters, they may not know the address and port. The correct status for the external service should be "unknown" since PMM does not have enough information to determine the exporter's status.

Furthermore, the monitoring status should be "OK" since PMM can still collect metrics from the exporter, even if it cannot determine the exporter's status.

This bug can cause confusion for users and make it difficult for them to determine the actual status of the monitored services. It is recommended to update the PMM monitoring feature to display an "unknown" status for external services when the exporter does not know the address and port, and to display a monitoring status of "OK" when metrics can still be collected from the exporter.