Fix target allocator readiness check

.chloggen/fix_load-initial-servicemonitors.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. collector, target allocator, auto-instrumentation, opamp, github action)
+component: target allocator
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix target allocator readiness check
+
+# One or more tracking issues related to the change
+issues: [2903]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

cmd/otel-allocator/main.go

@@ -111,6 +111,17 @@ func main() {
 			setupLog.Error(err, "Can't start the prometheus watcher")
 			os.Exit(1)
 		}
+		// apply the initial configuration
+		promConfig, loadErr := promWatcher.LoadConfig(ctx)
+		if loadErr != nil {
+			setupLog.Error(err, "Can't load initial Prometheus configuration from Prometheus CRs")
+			os.Exit(1)
+		}
+		loadErr = targetDiscoverer.ApplyConfig(allocatorWatcher.EventSourcePrometheusCR, promConfig.ScrapeConfigs)
+		if loadErr != nil {
+			setupLog.Error(err, "Can't load initial scrape targets from Prometheus CRs")
+			os.Exit(1)
+		}
 		runGroup.Add(
 			func() error {
 				promWatcherErr := promWatcher.Watch(eventChan, errChan)
@@ -138,7 +149,7 @@ func main() {
 	runGroup.Add(
 		func() error {
 			// Initial loading of the config file's scrape config
-			if cfg.PromConfig != nil {
+			if cfg.PromConfig != nil && len(cfg.PromConfig.ScrapeConfigs) > 0 {
 				err = targetDiscoverer.ApplyConfig(allocatorWatcher.EventSourceConfigMap, cfg.PromConfig.ScrapeConfigs)
 				if err != nil {
 					setupLog.Error(err, "Unable to apply initial configuration")

internal/manifests/targetallocator/configmap.go

@@ -40,7 +40,7 @@ func ConfigMap(params manifests.Params) (*corev1.ConfigMap, error) {
 	taConfig["collector_selector"] = taSpec.CollectorSelector
 
 	// Add scrape configs if present
-	if instance.Spec.ScrapeConfigs != nil {
+	if instance.Spec.ScrapeConfigs != nil && len(instance.Spec.ScrapeConfigs) > 0 {
 		taConfig["config"] = map[string]interface{}{
 			"scrape_configs": instance.Spec.ScrapeConfigs,
 		}

internal/manifests/targetallocator/configmap_test.go

@@ -23,6 +23,7 @@ import (
 	"github.com/stretchr/testify/require"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
+	"github.com/open-telemetry/opentelemetry-operator/apis/v1beta1"
 	"github.com/open-telemetry/opentelemetry-operator/internal/config"
 	"github.com/open-telemetry/opentelemetry-operator/internal/manifests"
 )
@@ -78,6 +79,43 @@ prometheus_cr:
 		assert.Equal(t, expectedLabels, actual.Labels)
 		assert.Equal(t, expectedData[targetAllocatorFilename], actual.Data[targetAllocatorFilename])
 
+	})
+	t.Run("should return target allocator config map without scrape configs", func(t *testing.T) {
+		expectedLabels["app.kubernetes.io/component"] = "opentelemetry-targetallocator"
+		expectedLabels["app.kubernetes.io/name"] = "my-instance-targetallocator"
+
+		expectedData := map[string]string{
+			targetAllocatorFilename: `allocation_strategy: consistent-hashing
+collector_selector:
+  matchlabels:
+    app.kubernetes.io/component: opentelemetry-collector
+    app.kubernetes.io/instance: default.my-instance
+    app.kubernetes.io/managed-by: opentelemetry-operator
+    app.kubernetes.io/part-of: opentelemetry
+  matchexpressions: []
+filter_strategy: relabel-config
+prometheus_cr:
+  pod_monitor_selector: null
+  service_monitor_selector: null
+`,
+		}
+		collector := collectorInstance()
+		targetAllocator := targetAllocatorInstance()
+		targetAllocator.Spec.ScrapeConfigs = []v1beta1.AnyConfig{}
+		cfg := config.New()
+		params := manifests.Params{
+			OtelCol:         collector,
+			TargetAllocator: targetAllocator,
+			Config:          cfg,
+			Log:             logr.Discard(),
+		}
+		actual, err := ConfigMap(params)
+		require.NoError(t, err)
+
+		assert.Equal(t, "my-instance-targetallocator", actual.Name)
+		assert.Equal(t, expectedLabels, actual.Labels)
+		assert.Equal(t, expectedData[targetAllocatorFilename], actual.Data[targetAllocatorFilename])
+
 	})
 	t.Run("should return expected target allocator config map with label selectors", func(t *testing.T) {
 		expectedLabels["app.kubernetes.io/component"] = "opentelemetry-targetallocator"

tests/e2e-targetallocator/targetallocator-prometheuscr/00-install.yaml

@@ -155,16 +155,5 @@ spec:
     enabled: true
     prometheusCR:
       enabled: true
-    scrapeInterval: 1s
+      scrapeInterval: 1s
     serviceAccount: ta
----
-apiVersion: monitoring.coreos.com/v1
-kind: ServiceMonitor
-metadata:
-  name: prometheus-cr
-spec:
-  endpoints:
-  - port: monitoring
-  selector:
-    matchLabels:
-      app.kubernetes.io/managed-by: opentelemetry-operator

tests/e2e-targetallocator/targetallocator-prometheuscr/01-install.yaml

@@ -1,4 +1,15 @@
 ---
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: prometheus-cr
+spec:
+  endpoints:
+    - port: monitoring
+  selector:
+    matchLabels:
+      app.kubernetes.io/managed-by: opentelemetry-operator
+---
 apiVersion: batch/v1
 kind: Job
 metadata: