[featuregate] Automatically set GOMEMLIMIT and GOMAXPROCS for collector, target allocator, opamp bridge (open-telemetry#2933)

* set things

* fix kustomize shim

* restore, better chlog

Author: jaronoff97

.chloggen/set-gomemlimit.yaml

@@ -0,0 +1,18 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# 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: collector, target allocator, opamp
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Introduces a new feature gate for `operator.golang.flags` to automatically add the environment variables for GOMAXPROCS and GOMEMLIMIT
+
+# One or more tracking issues related to the change
+issues: [2919, 1456]
+
+# (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: |
+  A new featuregate `operator.golang.flags` is added. This featuregate will allow the operator to automatically
+  set GOMAXPROCS and GOMEMLIMIT equal to the CPU and Memory limit provided respectively for the pod. 

internal/manifests/collector/container.go

@@ -29,6 +29,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-operator/internal/config"
 	"github.com/open-telemetry/opentelemetry-operator/internal/manifests/collector/adapters"
 	"github.com/open-telemetry/opentelemetry-operator/internal/naming"
+	"github.com/open-telemetry/opentelemetry-operator/pkg/featuregate"
 )
 
 // maxPortLen allows us to truncate a port name according to what is considered valid port syntax:
@@ -163,6 +164,28 @@ func Container(cfg config.Config, logger logr.Logger, otelcol v1beta1.OpenTeleme
 		}
 	}
 
+	if featuregate.SetGolangFlags.IsEnabled() {
+		envVars = append(envVars, corev1.EnvVar{
+			Name: "GOMEMLIMIT",
+			ValueFrom: &corev1.EnvVarSource{
+				ResourceFieldRef: &corev1.ResourceFieldSelector{
+					Resource:      "limits.memory",
+					ContainerName: naming.Container(),
+				},
+			},
+		},
+			corev1.EnvVar{
+				Name: "GOMAXPROCS",
+				ValueFrom: &corev1.EnvVarSource{
+					ResourceFieldRef: &corev1.ResourceFieldSelector{
+						Resource:      "limits.cpu",
+						ContainerName: naming.Container(),
+					},
+				},
+			},
+		)
+	}
+
 	envVars = append(envVars, proxy.ReadProxyVarsFromEnv()...)
 	return corev1.Container{
 		Name:            naming.Container(),

internal/manifests/opampbridge/container.go

@@ -22,6 +22,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-operator/apis/v1alpha1"
 	"github.com/open-telemetry/opentelemetry-operator/internal/config"
 	"github.com/open-telemetry/opentelemetry-operator/internal/naming"
+	"github.com/open-telemetry/opentelemetry-operator/pkg/featuregate"
 )
 
 // Container builds a container for the given OpAMPBridge.
@@ -62,6 +63,28 @@ func Container(cfg config.Config, logger logr.Logger, opampBridge v1alpha1.OpAMP
 		})
 	}
 
+	if featuregate.SetGolangFlags.IsEnabled() {
+		envVars = append(envVars, corev1.EnvVar{
+			Name: "GOMEMLIMIT",
+			ValueFrom: &corev1.EnvVarSource{
+				ResourceFieldRef: &corev1.ResourceFieldSelector{
+					Resource:      "limits.memory",
+					ContainerName: naming.OpAMPBridgeContainer(),
+				},
+			},
+		},
+			corev1.EnvVar{
+				Name: "GOMAXPROCS",
+				ValueFrom: &corev1.EnvVarSource{
+					ResourceFieldRef: &corev1.ResourceFieldSelector{
+						Resource:      "limits.cpu",
+						ContainerName: naming.OpAMPBridgeContainer(),
+					},
+				},
+			},
+		)
+	}
+
 	envVars = append(envVars, proxy.ReadProxyVarsFromEnv()...)
 
 	return corev1.Container{

internal/manifests/targetallocator/container.go

@@ -23,6 +23,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-operator/apis/v1alpha1"
 	"github.com/open-telemetry/opentelemetry-operator/internal/config"
 	"github.com/open-telemetry/opentelemetry-operator/internal/naming"
+	"github.com/open-telemetry/opentelemetry-operator/pkg/featuregate"
 )
 
 // Container builds a container for the given TargetAllocator.
@@ -66,6 +67,28 @@ func Container(cfg config.Config, logger logr.Logger, instance v1alpha1.TargetAl
 		})
 	}
 
+	if featuregate.SetGolangFlags.IsEnabled() {
+		envVars = append(envVars, corev1.EnvVar{
+			Name: "GOMEMLIMIT",
+			ValueFrom: &corev1.EnvVarSource{
+				ResourceFieldRef: &corev1.ResourceFieldSelector{
+					Resource:      "limits.memory",
+					ContainerName: naming.TAContainer(),
+				},
+			},
+		},
+			corev1.EnvVar{
+				Name: "GOMAXPROCS",
+				ValueFrom: &corev1.EnvVarSource{
+					ResourceFieldRef: &corev1.ResourceFieldSelector{
+						Resource:      "limits.cpu",
+						ContainerName: naming.TAContainer(),
+					},
+				},
+			},
+		)
+	}
+
 	var args []string
 	if instance.Spec.PrometheusCR.Enabled {
 		args = append(args, "--enable-prometheus-cr-watcher")

pkg/featuregate/featuregate.go

@@ -32,6 +32,14 @@ var (
 		featuregate.WithRegisterDescription("enables features associated to the Prometheus Operator"),
 		featuregate.WithRegisterFromVersion("v0.82.0"),
 	)
+	// SetGolangFlags is the feature gate that enables automatically setting GOMEMLIMIT and GOMAXPROCS for the
+	// collector, bridge, and target allocator.
+	SetGolangFlags = featuregate.GlobalRegistry().MustRegister(
+		"operator.golang.flags",
+		featuregate.StageAlpha,
+		featuregate.WithRegisterDescription("enables feature to set GOMEMLIMIT and GOMAXPROCS automatically"),
+		featuregate.WithRegisterFromVersion("v0.100.0"),
+	)
 )
 
 // Flags creates a new FlagSet that represents the available featuregate flags using the supplied featuregate registry.