Add support for configuring the K8s resources for injected collectors

[jfiedler]

It would be nice if K8s resources of the injected collectors (for sidecar mode) could be configured via the operator CRD. This is an important requirement when using horizontal pod autoscalers later on. Containers in a pod that have no resource requests can cause issues with HPA.

[jpkrohling]

Would you like to contribute with a PR? Should be relatively easy to do it: add a Resources node here, similar to what v1.Container has:

opentelemetry-operator/api/v1alpha1/opentelemetrycollector_types.go

Lines 23 to 79 in 33f21cc

	type OpenTelemetryCollectorSpec struct {
	// Config is the raw JSON to be used as the collector's configuration. Refer to the OpenTelemetry Collector documentation for details.
	// +required
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Config string `json:"config,omitempty"`
	// Args is the set of arguments to pass to the OpenTelemetry Collector binary
	// +optional
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Args map[string]string `json:"args,omitempty"`
	// Replicas is the number of pod instances for the underlying OpenTelemetry Collector
	// +optional
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Replicas *int32 `json:"replicas,omitempty"`
	// Image indicates the container image to use for the OpenTelemetry Collector.
	// +optional
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Image string `json:"image,omitempty"`
	// Mode represents how the collector should be deployed (deployment, daemonset or sidecar)
	// +optional
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Mode Mode `json:"mode,omitempty"`
	// ServiceAccount indicates the name of an existing service account to use with this instance.
	// +optional
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	ServiceAccount string `json:"serviceAccount,omitempty"`
	// VolumeMounts represents the mount points to use in the underlying collector deployment(s)
	// +optional
	// +listType=atomic
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	VolumeMounts []v1.VolumeMount `json:"volumeMounts,omitempty"`
	// Volumes represents which volumes to use in the underlying collector deployment(s).
	// +optional
	// +listType=atomic
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Volumes []v1.Volume `json:"volumes,omitempty"`
	// Ports allows a set of ports to be exposed by the underlying v1.Service. By default, the operator
	// will attempt to infer the required ports by parsing the .Spec.Config property but this property can be
	// used to open aditional ports that can't be inferred by the operator, like for custom receivers.
	// +optional
	// +listType=atomic
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Ports []v1.ServicePort `json:"ports,omitempty"`
	// ENV vars to set on the OpenTelemetry Collector's Pods. These can then in certain cases be
	// consumed in the config file for the Collector.
	// +optional
	// +operator-sdk:gen-csv:customresourcedefinitions.specDescriptors=true
	Env []v1.EnvVar `json:"env,omitempty"`
	}

Then apply it here:

opentelemetry-operator/pkg/collector/container.go

Lines 66 to 72 in 33f21cc

	return corev1.Container{
	Name: naming.Container(),
	Image: image,
	VolumeMounts: volumeMounts,
	Args: args,
	Env: envVars,
	}

[jfiedler]

Sure. I will give it a shot.