Improve YAML parsing to handle list sequences within SLI spec

internal/fmt/fmt.go

@@ -34,7 +34,9 @@ func Files(out io.Writer, sources []string) error {
 			return err
 		}
 		if i != count-1 {
-			fmt.Fprintln(out, "---")
+			if _, err := fmt.Fprintln(out, "---"); err != nil {
+				return err
+			}
 		}
 	}
 	return nil

pkg/manifest/v1/indicator.go

@@ -70,15 +70,15 @@ type MetricSource struct {
 	MetricSourceSpec map[string]string `yaml:"spec" validate:"required_without=MetricSourceRef"`
 }
 
-// UnmarshalYAML is used to override the default unmarshal behavior
-// Since MetricSources don't have a determined structure, we need to do a few things here:
-//  1. Pull out the MetricSourceRef and Type separately, and add them to the MetricSource
-//  2. Attempt to unmarshal the MetricSourceSpec, which can be either a string or an array.
-//     2a.  If its a string, add it as a single string
-//     2b.  If its an array, flatten it to a single string
-//
-// This also assumes a certain flat structure that we can revisit if the need arises.
+// UnmarshalYAML is used to override the default unmarshal behavior.
+// MetricSources can have varying structures, so this method performs the following tasks:
+//  1. Extracts the MetricSourceRef and Type separately, and assigns them to the MetricSource.
+//  2. Attempts to unmarshal the MetricSourceSpec, which can be either a string, a list, or a more complex structure:
+//     2a. If it's a scalar string, it is added directly as a single string.
+//     2b. If it's a list of scalar values, they are concatenated into a single semicolon separated string.
+//     2c. If it's a more complex sequence (e.g., containing mappings), the values are processed and flattened appropriately.
 //
+// The current implementation assumes a relatively flat structure but can be adapted if more complex nesting becomes necessary.
 
 func (m *MetricSource) UnmarshalYAML(value *yaml.Node) error {
 	// temp struct to unmarshal the string values
@@ -108,7 +108,9 @@ func (m *MetricSource) UnmarshalYAML(value *yaml.Node) error {
 			// top level string that we will join with a semicolon
 			seqStrings := []string{}
 			for _, node := range v.Content {
-				if node.Kind == yaml.MappingNode {
+				if node.Kind == yaml.ScalarNode {
+					seqStrings = append(seqStrings, node.Value)
+				} else if node.Kind == yaml.MappingNode {
 					// each of these are k/v pairs that we will join with a comma
 					kvPairs := []string{}
 					for i := 0; i < len(node.Content); i += 2 {

pkg/manifest/v1/indicator_test.go

@@ -81,6 +81,24 @@ spec:
 				},
 			},
 		},
+		{
+			name: "Prometheus - Two labels",
+			yaml: `metricSourceRef: thanos
+type: Prometheus
+spec:
+  query: http_requests_total{}
+  dimensions:
+    - following
+    - another`,
+			want: MetricSource{
+				MetricSourceRef: "thanos",
+				Type:            "Prometheus",
+				MetricSourceSpec: map[string]string{
+					"query":      "http_requests_total{}",
+					"dimensions": "following;another",
+				},
+			},
+		},
 	}
 
 	for _, tt := range tests {

pkg/manifest/v1/objective.go

@@ -32,19 +32,22 @@ type TimeWindow struct {
 
 // Objective represents single threshold for SLO, for internal usage.
 type Objective struct {
-	DisplayName     string  `yaml:"displayName,omitempty"`
-	Op              string  `yaml:"op,omitempty" example:"lte"`
-	Value           float64 `yaml:"value,omitempty" validate:"numeric,omitempty"`
-	Target          float64 `yaml:"target" validate:"required,numeric,gte=0,lt=1" example:"0.9"`
-	TimeSliceTarget float64 `yaml:"timeSliceTarget,omitempty" validate:"gte=0,lte=1,omitempty" example:"0.9"`
-	TimeSliceWindow string  `yaml:"timeSliceWindow,omitempty" example:"5m"`
+	DisplayName     string     `yaml:"displayName,omitempty"`
+	Op              string     `yaml:"op,omitempty" example:"lte"`
+	Value           float64    `yaml:"value,omitempty" validate:"numeric,omitempty"`
+	Target          float64    `yaml:"target" validate:"required,numeric,gte=0,lt=1" example:"0.9"`
+	TimeSliceTarget float64    `yaml:"timeSliceTarget,omitempty" validate:"gte=0,lte=1,omitempty" example:"0.9"`
+	TimeSliceWindow string     `yaml:"timeSliceWindow,omitempty" example:"5m"`
+	Indicator       *SLIInline `yaml:"indicator,omitempty"`
+	IndicatorRef    *string    `yaml:"indicatorRef,omitempty"`
+	CompositeWeight float64    `yaml:"compositeWeight,omitempty" validate:"gte=0,omitempty"`
 }
 
 // SLOSpec struct which mapped one to one with kind: slo yaml definition, internal use.
 type SLOSpec struct {
 	Description     string       `yaml:"description,omitempty" validate:"max=1050,omitempty"`
 	Service         string       `yaml:"service" validate:"required" example:"webapp-service"`
-	Indicator       *SLIInline   `yaml:"indicator,omitempty" validate:"required_without=IndicatorRef"`
+	Indicator       *SLIInline   `yaml:"indicator,omitempty"`
 	IndicatorRef    *string      `yaml:"indicatorRef,omitempty"`
 	BudgetingMethod string       `yaml:"budgetingMethod" validate:"required,oneof=Occurrences Timeslices" example:"Occurrences"` //nolint:lll
 	TimeWindow      []TimeWindow `yaml:"timeWindow" validate:"required,len=1,dive"`

pkg/validate/validate_test.go

@@ -180,6 +180,8 @@ func Test_validateFiles(t *testing.T) {
 					"../../test/v1/slo/slo-no-indicatorref-calendar-no-alerts.yaml",
 					"../../test/v1/slo/slo-no-indicatorref-rolling-alerts.yaml",
 					"../../test/v1/slo/slo-no-indicatorref-rolling-no-alerts.yaml",
+					"../../test/v1/slo/slo-composite-indicatorRef-rolling-no-alerts.yaml",
+					"../../test/v1/slo/slo-composite-no-indicatorRef-rolling-no-alerts.yaml",
 				},
 			},
 			wantErr: false,

test/v1/slo/slo-composite-indicatorRef-rolling-no-alerts.yaml

@@ -0,0 +1,21 @@
+apiVersion: openslo/v1
+kind: SLO
+metadata:
+  name: TestSLO
+  displayName: Test SLO # optional
+spec:
+  description: This is a great description # optional
+  service: TheServiceName # name of the service to associate this SLO with
+  timeWindow:
+    - duration: 1d
+      isRolling: true
+  budgetingMethod: Occurrences
+  objectives:
+    - displayName: Foo Total Errors
+      target: 0.98
+      compositeWeight: 1
+      indicatorRef: indicatorRefString # name of the SLI. Required if indicator is not given.
+    - displayName: Bar Total Errors
+      target: 0.99
+      compositeWeight: 2
+      indicatorRef: indicatorRefString # name of the SLI. Required if indicator is not given.

test/v1/slo/slo-composite-no-indicatorRef-rolling-no-alerts.yaml

@@ -0,0 +1,57 @@
+apiVersion: openslo/v1
+kind: SLO
+metadata:
+  name: TestSLO
+  displayName: Test SLO
+spec:
+  description: This is a great description
+  service: TheServiceName
+  timeWindow:
+    - duration: 1M
+      isRolling: true
+  budgetingMethod: Occurrences
+  objectives:
+    - displayName: Foo Total Errors
+      target: 0.98
+      compositeWeight: 1
+      indicator:
+        metadata:
+          name: foo-error
+          displayName: Foo Error
+        spec:
+          ratioMetric:
+            counter: true
+            good:
+              metricSource:
+                metricSourceRef: datadog-datasource
+                type: Datadog
+                spec:
+                  query: sum:trace.http.request.hits.by_http_status{http.status_code:200}.as_count()
+            total:
+              metricSource:
+                metricSourceRef: datadog-datasource
+                type: Datadog
+                spec:
+                  query: sum:trace.http.request.hits.by_http_status{*}.as_count()
+    - displayName: Bar Total Errors
+      target: 0.99
+      compositeWeight: 2
+      indicator:
+        metadata:
+          name: foo-error
+          displayName: Foo Error
+        spec:
+          ratioMetric:
+            counter: true
+            good:
+              metricSource:
+                metricSourceRef: datadog-datasource
+                type: Datadog
+                spec:
+                  query: sum:trace.http.request.hits.by_http_status{http.status_code:200}.as_count()
+            total:
+              metricSource:
+                metricSourceRef: datadog-datasource
+                type: Datadog
+                spec:
+                  query: sum:trace.http.request.hits.by_http_status{*}.as_count()