Enable multi instrumentation by default

.chloggen/3090-enable-multiinstrumentation-by-default.yaml

@@ -0,0 +1,30 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'breaking'
+
+# 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: auto-instrumentation
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Enable multi instrumentation by default.
+
+# One or more tracking issues related to the change
+issues: [3090]
+
+# (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: |
+  Starting with this release, the OpenTelemetry Operator now enables multi-instrumentation by default.
+  This enhancement allows instrumentation of multiple containers in a pod with language-specific configurations.|
+  Key Changes:
+    - Single Instrumentation (Default Behavior): If no container names are specified using the
+      `instrumentation.opentelemetry.io/container-names` annotation, instrumentation will be applied to the first container in
+      the pod spec by default. This only applies when single instrumentation injection is configured.
+    - Multi-Container Pods: In scenarios where different containers in a pod use distinct technologies, users must specify the
+      container(s) for instrumentation using language-specific annotations. Without this specification, the default behavior may
+      not work as expected for multi-container environments.
+  Compatibility:
+    - Users already utilizing the `instrumentation.opentelemetry.io/container-names` annotation do not need to take any action.
+      Their existing setup will continue to function as before.
+    - Important: Users who attempt to configure both `instrumentation.opentelemetry.io/container-names` and language-specific annotations
+      (for multi-instrumentation) simultaneously will encounter an error, as this configuration is not supported.

.github/workflows/e2e.yaml

@@ -38,7 +38,7 @@ jobs:
          - group: e2e-instrumentation
            setup: "add-instrumentation-params prepare-e2e"
          - group: e2e-multi-instrumentation
-           setup: "add-multi-instrumentation-params prepare-e2e"
+           setup: "add-instrumentation-params prepare-e2e"
          - group: e2e-metadata-filters
            setup: "add-operator-arg OPERATOR_ARG='--annotations-filter=.*filter.out --annotations-filter=config.*.gke.io.* --labels-filter=.*filter.out' prepare-e2e"
          - group: e2e-automatic-rbac

main.go

@@ -151,7 +151,7 @@ func main() {
 			"Enabling this will ensure there is only one active controller manager.")
 	pflag.BoolVar(&createRBACPermissions, "create-rbac-permissions", false, "Automatically create RBAC permissions needed by the processors (deprecated)")
 	pflag.BoolVar(&createOpenShiftDashboard, "openshift-create-dashboard", false, "Create an OpenShift dashboard for monitoring the OpenTelemetryCollector instances")
-	pflag.BoolVar(&enableMultiInstrumentation, "enable-multi-instrumentation", false, "Controls whether the operator supports multi instrumentation")
+	pflag.BoolVar(&enableMultiInstrumentation, "enable-multi-instrumentation", true, "Controls whether the operator supports multi instrumentation")
 	pflag.BoolVar(&enableApacheHttpdInstrumentation, constants.FlagApacheHttpd, true, "Controls whether the operator supports Apache HTTPD auto-instrumentation")
 	pflag.BoolVar(&enableDotNetInstrumentation, constants.FlagDotNet, true, "Controls whether the operator supports dotnet auto-instrumentation")
 	pflag.BoolVar(&enableGoInstrumentation, constants.FlagGo, false, "Controls whether the operator supports Go auto-instrumentation")

tests/e2e-instrumentation/instrumentation-apache-multicontainer/01-assert.yaml

@@ -13,10 +13,12 @@ spec:
     - name: OTEL_NODE_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.hostIP
     - name: OTEL_POD_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.podIP
     - name: OTEL_SERVICE_NAME
       value: my-apache-multi
@@ -44,10 +46,12 @@ spec:
     - name: OTEL_NODE_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.hostIP
     - name: OTEL_POD_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.podIP
     - name: OTEL_SERVICE_NAME
       value: my-apache-multi

tests/e2e-instrumentation/instrumentation-apache-multicontainer/02-assert.yaml

@@ -24,10 +24,12 @@ spec:
     - name: OTEL_NODE_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.hostIP
     - name: OTEL_POD_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.podIP
     - name: OTEL_SERVICE_NAME
       value: my-apache-multi

tests/e2e-instrumentation/instrumentation-nginx-multicontainer/01-assert.yaml

@@ -13,10 +13,12 @@ spec:
     - name: OTEL_NODE_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.hostIP
     - name: OTEL_POD_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.podIP
     - name: LD_LIBRARY_PATH
       value: /opt:/opt/opentelemetry-webserver/agent/sdk_lib/lib
@@ -53,10 +55,12 @@ spec:
     - name: OTEL_NODE_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.hostIP
     - name: OTEL_POD_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.podIP
     - name: OTEL_SERVICE_NAME
       value: my-nginx-multi

tests/e2e-instrumentation/instrumentation-nginx-multicontainer/01-install-app.yaml

@@ -45,7 +45,6 @@ spec:
             mountPath: /etc/nginx/nginx.conf
             subPath: nginx.conf
             readOnly: true
-        imagePullPolicy: Always
         resources:
           limits:
             cpu: 500m

tests/e2e-instrumentation/instrumentation-nginx-multicontainer/02-assert.yaml

@@ -24,10 +24,12 @@ spec:
     - name: OTEL_NODE_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.hostIP
     - name: OTEL_POD_IP
       valueFrom:
         fieldRef:
+          apiVersion: v1
           fieldPath: status.podIP
     - name: LD_LIBRARY_PATH
       value: /opt:/opt/opentelemetry-webserver/agent/sdk_lib/lib