API docs does not fully reflect the actual implementation: enroll accept null tags

[AndersonQ]

For confirmed bugs, please report:

• Version: 8.14.2, main, most likely others
• Operating System: N/A
• Discuss Forum URL: N/A
• Steps to Reproduce: N/A

The api/fleet/agents/enroll, API states on the openAPI definition tags is required, however fleet-server accepts it as null.

In the code we don't fully validate the received data:

fleet-server/internal/pkg/api/handleEnroll.go

Lines 521 to 539 in 53ebe67

	func validateRequest(ctx context.Context, data io.Reader) (*EnrollRequest, error) {
	span, _ := apm.StartSpan(ctx, "validateRequest", "validate")
	defer span.End()
	var req EnrollRequest
	decoder := json.NewDecoder(data)
	if err := decoder.Decode(&req); err != nil {
	return nil, &BadRequestErr{msg: "unable to decode enroll request", nextErr: err}
	}
	// Validate
	switch req.Type {
	case EnrollEphemeral, EnrollPermanent, EnrollTemporary:
	default:
	return nil, ErrUnknownEnrollType
	}
	return &req, nil
	}

the model allows for a null or absent tags property:

fleet-server/internal/pkg/api/openapi.gen.go

Lines 354 to 374 in 3c5b375

	// EnrollMetadata Metadata associated with the agent that is enrolling to fleet.
	type EnrollMetadata struct {
	// Local An embedded JSON object that holds meta-data values.
	// Defined in fleet-server as a `json.RawMessage`, defined as an object in the elastic-agent.
	// elastic-agent will populate the object with information from the binary and host/system environment.
	// If not empty fleet-server will update the value of `local["elastic"]["agent"]["id"]` to the agent ID (assuming the keys exist).
	// The (possibly updated) value is sent by fleet-server when creating the record for a new agent.
	Local json.RawMessage `json:"local"`
	// Tags User provided tags for the agent.
	// fleet-server will pass the tags to the agent record on enrollment.
	Tags []string `json:"tags"`
	// UserProvided An embedded JSON object that holds user-provided meta-data values.
	// Defined in fleet-server as a `json.RawMessage`.
	// fleet-server does not use these values on enrollment of an agent.
	//
	// Defined in the elastic-agent as a `map[string]interface{}` with no way to specify any values.
	// Deprecated:
	UserProvided json.RawMessage `json:"user_provided"`
	}

Perhaps it'd be worth to double check our whole OpenAPI definition against the actual implementation