Support for storage.tsdb.retention.size for prometheus 2.7+

Documentation/api.md

@@ -278,6 +278,7 @@ PrometheusSpec is a specification of the desired behavior of the Prometheus clus
 | replicaExternalLabelName | Name of Prometheus external label used to denote replica name. Defaults to the value of `prometheus_replica`. External label will _not_ be added when value is set to empty string (`\"\"`). | *string | false |
 | prometheusExternalLabelName | Name of Prometheus external label used to denote Prometheus instance name. Defaults to the value of `prometheus`. External label will _not_ be added when value is set to empty string (`\"\"`). | *string | false |
 | retention | Time duration Prometheus shall retain data for. Default is '24h', and must match the regular expression `[0-9]+(ms\|s\|m\|h\|d\|w\|y)` (milliseconds seconds minutes hours days weeks years). | string | false |
+| retentionSize | Maximum amount of disk space used by blocks. | string | false |
 | logLevel | Log level for Prometheus to be configured with. | string | false |
 | logFormat | Log format for Prometheus to be configured with. | string | false |
 | scrapeInterval | Interval between consecutive scrapes. | string | false |

example/prometheus-operator-crd/prometheus.crd.yaml

@@ -2338,6 +2338,9 @@ spec:
                 is '24h', and must match the regular expression `[0-9]+(ms|s|m|h|d|w|y)`
                 (milliseconds seconds minutes hours days weeks years).
               type: string
+            retentionSize:
+              description: Maximum amount of disk space used by blocks.
+              type: string
             routePrefix:
               description: The route prefix Prometheus registers HTTP handlers for.
                 This is useful, if using ExternalURL and a proxy is rewriting HTTP

pkg/apis/monitoring/v1/openapi_generated.go

@@ -1346,6 +1346,13 @@ func schema_pkg_apis_monitoring_v1_PrometheusSpec(ref common.ReferenceCallback)
 							Format:      "",
 						},
 					},
+					"retentionSize": {
+						SchemaProps: spec.SchemaProps{
+							Description: "Maximum amount of disk space used by blocks.",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
 					"logLevel": {
 						SchemaProps: spec.SchemaProps{
 							Description: "Log level for Prometheus to be configured with.",

pkg/apis/monitoring/v1/types.go

@@ -120,6 +120,8 @@ type PrometheusSpec struct {
 	// Time duration Prometheus shall retain data for. Default is '24h',
 	// and must match the regular expression `[0-9]+(ms|s|m|h|d|w|y)` (milliseconds seconds minutes hours days weeks years).
 	Retention string `json:"retention,omitempty"`
+	// Maximum amount of disk space used by blocks.
+	RetentionSize string `json:"retentionSize,omitempty"`
 	// Log level for Prometheus to be configured with.
 	LogLevel string `json:"logLevel,omitempty"`
 	// Log format for Prometheus to be configured with.

pkg/prometheus/statefulset.go

@@ -339,6 +339,11 @@ func makeStatefulSetSpec(p monitoringv1.Prometheus, c *Config, ruleConfigMapName
 		retentionTimeFlag := "-storage.tsdb.retention="
 		if version.Minor >= 7 {
 			retentionTimeFlag = "-storage.tsdb.retention.time="
+			if p.Spec.RetentionSize != "" {
+				promArgs = append(promArgs,
+					fmt.Sprintf("-storage.tsdb.retention.size=%s", p.Spec.RetentionSize),
+				)
+			}
 		}
 		promArgs = append(promArgs,
 			fmt.Sprintf("-config.file=%s", path.Join(confOutDir, configEnvsubstFilename)),

pkg/prometheus/statefulset_test.go

@@ -609,6 +609,51 @@ func TestThanosObjectStorage(t *testing.T) {
 	}
 }
 
+func TestRetentionSize(t *testing.T) {
+	tests := []struct {
+		version              string
+		specRetentionSize    string
+		expectedRetentionArg string
+		shouldContain        bool
+	}{
+		{"v1.8.2", "2M", "--storage.tsdb.retention.size=2M", false},
+		{"v1.8.2", "1Gi", "--storage.tsdb.retention.size=1Gi", false},
+		{"v2.5.0", "2M", "--storage.tsdb.retention.size=2M", false},
+		{"v2.5.0", "1Gi", "--storage.tsdb.retention.size=1Gi", false},
+		{"v2.7.0", "2M", "--storage.tsdb.retention.size=2M", true},
+		{"v2.7.0", "1Gi", "--storage.tsdb.retention.size=1Gi", true},
+	}
+
+	for _, test := range tests {
+		sset, err := makeStatefulSet(monitoringv1.Prometheus{
+			Spec: monitoringv1.PrometheusSpec{
+				Version:   test.version,
+				RetentionSize: test.specRetentionSize,
+			},
+		}, defaultTestConfig, nil, "")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		promArgs := sset.Spec.Template.Spec.Containers[0].Args
+		found := false
+		for _, flag := range promArgs {
+			if flag == test.expectedRetentionArg {
+				found = true
+				break
+			}
+		}
+
+		if found != test.shouldContain {
+			if test.shouldContain {
+				t.Fatalf("expected Prometheus args to contain %v, but got %v", test.expectedRetentionArg, promArgs)
+			} else {
+				t.Fatalf("expected Prometheus args to NOT contain %v, but got %v", test.expectedRetentionArg, promArgs)
+			}
+		}
+	}
+}
+
 func TestRetention(t *testing.T) {
 	tests := []struct {
 		version              string