Add collectorSelector field to standalone TargetAllocator CR

.chloggen/ta_col_selector.yaml

@@ -0,0 +1,19 @@
+# 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: Add collectorSelector field to standalone TargetAllocator CR to prevent all pods in the namespace from being treated as collectors.
+
+# One or more tracking issues related to the change
+issues: [4818]
+
+# (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: |
+  When using the standalone TargetAllocator CR without a linked OpenTelemetryCollector, the collector_selector
+  was set to nil, causing all pods in the namespace to be treated as collectors. The new collectorSelector field
+  allows users to specify which pods should receive target assignments.

apis/v1alpha1/targetallocator_types.go

@@ -86,6 +86,12 @@ type TargetAllocatorSpec struct {
 	// NetworkPolicy defines the network policy to be applied to the Target Allocator pods.
 	// +optional
 	NetworkPolicy v1beta1.NetworkPolicy `json:"networkPolicy,omitempty"`
+	// CollectorSelector defines the label selector for collector pods that the TargetAllocator should
+	// assign targets to. This is required when using the standalone TargetAllocator CR without an
+	// associated OpenTelemetryCollector CR. If not set and no collector is linked, all pods in the
+	// namespace will be treated as collectors.
+	// +optional
+	CollectorSelector *metav1.LabelSelector `json:"collectorSelector,omitempty"`
 	// CollectorNotReadyGracePeriod defines the grace period after which a TargetAllocator stops considering a collector is target assignable.
 	// The default is 30s, which means that if a collector becomes not Ready, the target allocator will wait for 30 seconds before reassigning its targets. The assumption is that the state is temporary, and an expensive target reallocation should be avoided if possible.
 	//

bundle/community/manifests/opentelemetry-operator.clusterserviceversion.yaml

@@ -99,7 +99,7 @@ metadata:
     categories: Logging & Tracing,Monitoring,Observability
     certified: "false"
     containerImage: ghcr.io/open-telemetry/opentelemetry-operator/opentelemetry-operator
-    createdAt: "2026-03-04T12:42:01Z"
+    createdAt: "2026-03-08T23:17:33Z"
     description: Provides the OpenTelemetry components, including the Collector
     operators.operatorframework.io/builder: operator-sdk-v1.29.0
     operators.operatorframework.io/project_layout: go.kubebuilder.io/v3

bundle/community/manifests/opentelemetry.io_targetallocators.yaml

@@ -1215,6 +1215,32 @@ spec:
                 default: 30s
                 format: duration
                 type: string
+              collectorSelector:
+                properties:
+                  matchExpressions:
+                    items:
+                      properties:
+                        key:
+                          type: string
+                        operator:
+                          type: string
+                        values:
+                          items:
+                            type: string
+                          type: array
+                          x-kubernetes-list-type: atomic
+                      required:
+                      - key
+                      - operator
+                      type: object
+                    type: array
+                    x-kubernetes-list-type: atomic
+                  matchLabels:
+                    additionalProperties:
+                      type: string
+                    type: object
+                type: object
+                x-kubernetes-map-type: atomic
               dnsPolicy:
                 type: string
               env:

bundle/openshift/manifests/opentelemetry-operator.clusterserviceversion.yaml

@@ -99,7 +99,7 @@ metadata:
     categories: Logging & Tracing,Monitoring,Observability
     certified: "false"
     containerImage: ghcr.io/open-telemetry/opentelemetry-operator/opentelemetry-operator
-    createdAt: "2026-03-04T12:42:01Z"
+    createdAt: "2026-03-08T23:17:34Z"
     description: Provides the OpenTelemetry components, including the Collector
     operators.operatorframework.io/builder: operator-sdk-v1.29.0
     operators.operatorframework.io/project_layout: go.kubebuilder.io/v3

bundle/openshift/manifests/opentelemetry.io_targetallocators.yaml

@@ -1215,6 +1215,32 @@ spec:
                 default: 30s
                 format: duration
                 type: string
+              collectorSelector:
+                properties:
+                  matchExpressions:
+                    items:
+                      properties:
+                        key:
+                          type: string
+                        operator:
+                          type: string
+                        values:
+                          items:
+                            type: string
+                          type: array
+                          x-kubernetes-list-type: atomic
+                      required:
+                      - key
+                      - operator
+                      type: object
+                    type: array
+                    x-kubernetes-list-type: atomic
+                  matchLabels:
+                    additionalProperties:
+                      type: string
+                    type: object
+                type: object
+                x-kubernetes-map-type: atomic
               dnsPolicy:
                 type: string
               env:

config/crd/bases/opentelemetry.io_targetallocators.yaml

@@ -1213,6 +1213,32 @@ spec:
                 default: 30s
                 format: duration
                 type: string
+              collectorSelector:
+                properties:
+                  matchExpressions:
+                    items:
+                      properties:
+                        key:
+                          type: string
+                        operator:
+                          type: string
+                        values:
+                          items:
+                            type: string
+                          type: array
+                          x-kubernetes-list-type: atomic
+                      required:
+                      - key
+                      - operator
+                      type: object
+                    type: array
+                    x-kubernetes-list-type: atomic
+                  matchLabels:
+                    additionalProperties:
+                      type: string
+                    type: object
+                type: object
+                x-kubernetes-map-type: atomic
               dnsPolicy:
                 type: string
               env:

docs/api/targetallocators.md

@@ -137,6 +137,16 @@ The default is 30s, which means that if a collector becomes not Ready, the targe
             <i>Default</i>: 30s<br/>
         </td>
         <td>false</td>
+      </tr><tr>
+        <td><b><a href="#targetallocatorspeccollectorselector">collectorSelector</a></b></td>
+        <td>object</td>
+        <td>
+          CollectorSelector defines the label selector for collector pods that the TargetAllocator should
+assign targets to. This is required when using the standalone TargetAllocator CR without an
+associated OpenTelemetryCollector CR. If not set and no collector is linked, all pods in the
+namespace will be treated as collectors.<br/>
+        </td>
+        <td>false</td>
       </tr><tr>
         <td><b>dnsPolicy</b></td>
         <td>string</td>
@@ -5108,6 +5118,91 @@ operator is "In", and the values array contains only "value". The requirements a
 
 
 
+A label selector requirement is a selector that contains values, a key, and an operator that
+relates the key and values.
+
+<table>
+    <thead>
+        <tr>
+            <th>Name</th>
+            <th>Type</th>
+            <th>Description</th>
+            <th>Required</th>
+        </tr>
+    </thead>
+    <tbody><tr>
+        <td><b>key</b></td>
+        <td>string</td>
+        <td>
+          key is the label key that the selector applies to.<br/>
+        </td>
+        <td>true</td>
+      </tr><tr>
+        <td><b>operator</b></td>
+        <td>string</td>
+        <td>
+          operator represents a key's relationship to a set of values.
+Valid operators are In, NotIn, Exists and DoesNotExist.<br/>
+        </td>
+        <td>true</td>
+      </tr><tr>
+        <td><b>values</b></td>
+        <td>[]string</td>
+        <td>
+          values is an array of string values. If the operator is In or NotIn,
+the values array must be non-empty. If the operator is Exists or DoesNotExist,
+the values array must be empty. This array is replaced during a strategic
+merge patch.<br/>
+        </td>
+        <td>false</td>
+      </tr></tbody>
+</table>
+
+
+### TargetAllocator.spec.collectorSelector
+<sup><sup>[↩ Parent](#targetallocatorspec)</sup></sup>
+
+
+
+CollectorSelector defines the label selector for collector pods that the TargetAllocator should
+assign targets to. This is required when using the standalone TargetAllocator CR without an
+associated OpenTelemetryCollector CR. If not set and no collector is linked, all pods in the
+namespace will be treated as collectors.
+
+<table>
+    <thead>
+        <tr>
+            <th>Name</th>
+            <th>Type</th>
+            <th>Description</th>
+            <th>Required</th>
+        </tr>
+    </thead>
+    <tbody><tr>
+        <td><b><a href="#targetallocatorspeccollectorselectormatchexpressionsindex">matchExpressions</a></b></td>
+        <td>[]object</td>
+        <td>
+          matchExpressions is a list of label selector requirements. The requirements are ANDed.<br/>
+        </td>
+        <td>false</td>
+      </tr><tr>
+        <td><b>matchLabels</b></td>
+        <td>map[string]string</td>
+        <td>
+          matchLabels is a map of {key,value} pairs. A single {key,value} in the matchLabels
+map is equivalent to an element of matchExpressions, whose key field is "key", the
+operator is "In", and the values array contains only "value". The requirements are ANDed.<br/>
+        </td>
+        <td>false</td>
+      </tr></tbody>
+</table>
+
+
+### TargetAllocator.spec.collectorSelector.matchExpressions[index]
+<sup><sup>[↩ Parent](#targetallocatorspeccollectorselector)</sup></sup>
+
+
+
 A label selector requirement is a selector that contains values, a key, and an operator that
 relates the key and values.
 

internal/manifests/targetallocator/configmap.go

@@ -55,7 +55,7 @@ func ConfigMap(params Params) (*corev1.ConfigMap, error) {
 			return nil, err
 		}
 	} else { // if there's no collector, just use what's in the TargetAllocator CR
-		collectorSelector = nil
+		collectorSelector = taSpec.CollectorSelector
 		globalConfig = taSpec.GlobalConfig.Object
 		scrapeConfigs = taSpec.ScrapeConfigs
 	}

internal/manifests/targetallocator/configmap_test.go

@@ -70,8 +70,6 @@ collector_selector: null
 filter_strategy: relabel-config
 `,
 		}
-		targetAllocator := targetAllocatorInstance()
-		targetAllocator.Spec.ScrapeConfigs = []v1beta1.AnyConfig{}
 		testParams := Params{
 			Collector:       nil,
 			TargetAllocator: targetAllocatorInstance(),
@@ -83,6 +81,35 @@ filter_strategy: relabel-config
 		assert.Equal(t, expectedLabels, actual.Labels)
 		assert.Equal(t, expectedData[targetAllocatorFilename], actual.Data[targetAllocatorFilename])
 	})
+	t.Run("should return target allocator config map without collector but with collectorSelector", func(t *testing.T) {
+		expectedData := map[string]string{
+			targetAllocatorFilename: `allocation_strategy: consistent-hashing
+collector_selector:
+  matchlabels:
+    app.kubernetes.io/component: opentelemetry-collector
+    app.kubernetes.io/instance: my-collector
+  matchexpressions: []
+filter_strategy: relabel-config
+`,
+		}
+		ta := targetAllocatorInstance()
+		ta.Spec.CollectorSelector = &metav1.LabelSelector{
+			MatchLabels: map[string]string{
+				"app.kubernetes.io/component": "opentelemetry-collector",
+				"app.kubernetes.io/instance":  "my-collector",
+			},
+		}
+		testParams := Params{
+			Collector:       nil,
+			TargetAllocator: ta,
+		}
+		actual, err := ConfigMap(testParams)
+		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 target allocator config map without scrape configs", func(t *testing.T) {
 		expectedData := map[string]string{
 			targetAllocatorFilename: `allocation_strategy: consistent-hashing