Initial commit

checker/rule.go

@@ -0,0 +1,96 @@
+package checker
+
+import (
+	"context"
+	"fmt"
+
+	sdk "git.happydns.org/checker-sdk-go/checker"
+)
+
+// Rule returns a new dummy check rule.
+//
+// A rule evaluates collected observation data and returns a status (OK,
+// Warning, Critical, Error). Each checker can define multiple rules that
+// inspect the same data from different angles.
+func Rule() sdk.CheckRule {
+	return &dummyRule{}
+}
+
+// dummyRule implements the sdk.CheckRule interface.
+type dummyRule struct{}
+
+// Name returns a unique, stable identifier for this rule. It is used as the
+// "code" field in check results and stored in the database.
+func (r *dummyRule) Name() string { return "dummy_score_check" }
+
+// Description returns a human-readable summary of what this rule checks.
+func (r *dummyRule) Description() string {
+	return "Checks whether the dummy score is above the configured thresholds"
+}
+
+// ValidateOptions is called before evaluation to verify that the options are
+// well-formed. Return an error to reject invalid configuration early, before
+// any data collection happens.
+func (r *dummyRule) ValidateOptions(opts sdk.CheckerOptions) error {
+	warning := sdk.GetFloatOption(opts, "warningThreshold", 50)
+	critical := sdk.GetFloatOption(opts, "criticalThreshold", 20)
+
+	if warning < 0 || warning > 100 {
+		return fmt.Errorf("warningThreshold must be between 0 and 100")
+	}
+	if critical < 0 || critical > 100 {
+		return fmt.Errorf("criticalThreshold must be between 0 and 100")
+	}
+	if critical >= warning {
+		return fmt.Errorf("criticalThreshold (%v) must be less than warningThreshold (%v)", critical, warning)
+	}
+
+	return nil
+}
+
+// Evaluate inspects the collected observation data and returns a CheckState.
+//
+// Parameters:
+//   - ctx: context for cancellation.
+//   - obs: an ObservationGetter to retrieve collected data by key.
+//   - opts: the merged checker options.
+//
+// The ObservationGetter.Get method deserialises the stored JSON into your data
+// struct. Always check the error: the observation may not be available if
+// collection failed.
+func (r *dummyRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) sdk.CheckState {
+	// Retrieve the observation data by key.
+	var data DummyData
+	if err := obs.Get(ctx, ObservationKeyDummy, &data); err != nil {
+		return sdk.CheckState{
+			Status:  sdk.StatusError,
+			Message: fmt.Sprintf("Failed to get dummy data: %v", err),
+			Code:    "dummy_error",
+		}
+	}
+
+	// Read thresholds from options.
+	warningThreshold := sdk.GetFloatOption(opts, "warningThreshold", 50)
+	criticalThreshold := sdk.GetFloatOption(opts, "criticalThreshold", 20)
+
+	// Determine the status based on the score and thresholds.
+	var status sdk.Status
+	switch {
+	case data.Score < criticalThreshold:
+		status = sdk.StatusCrit
+	case data.Score < warningThreshold:
+		status = sdk.StatusWarn
+	default:
+		status = sdk.StatusOK
+	}
+
+	return sdk.CheckState{
+		Status:  status,
+		Message: fmt.Sprintf("Score: %.1f - %s", data.Score, data.Message),
+		Code:    "dummy_score_check",
+		Meta: map[string]any{
+			"score":   data.Score,
+			"message": data.Message,
+		},
+	}
+}