[chore] remove init function from prehook package (#3625)

* [chore] remove init function from prehook package

* remove Register

Author: atoulme

cmd/otel-allocator/prehook/prehook.go

@@ -15,18 +15,12 @@
 package prehook
 
 import (
-	"errors"
-
 	"github.com/go-logr/logr"
 	"github.com/prometheus/prometheus/model/relabel"
 
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
 )
 
-const (
-	relabelConfigTargetFilterName = "relabel-config"
-)
-
 type Hook interface {
 	Apply(map[string]*target.Item) map[string]*target.Item
 	SetConfig(map[string][]*relabel.Config)
@@ -36,7 +30,9 @@ type Hook interface {
 type HookProvider func(log logr.Logger) Hook
 
 var (
-	registry = map[string]HookProvider{}
+	registry = map[string]HookProvider{
+		relabelConfigTargetFilterName: newRelabelConfigTargetFilter,
+	}
 )
 
 func New(name string, log logr.Logger) Hook {
@@ -47,18 +43,3 @@ func New(name string, log logr.Logger) Hook {
 	log.Info("Unrecognized filter strategy; filtering disabled")
 	return nil
 }
-
-func Register(name string, provider HookProvider) error {
-	if _, ok := registry[name]; ok {
-		return errors.New("already registered")
-	}
-	registry[name] = provider
-	return nil
-}
-
-func init() {
-	err := Register(relabelConfigTargetFilterName, NewRelabelConfigTargetFilter)
-	if err != nil {
-		panic(err)
-	}
-}

cmd/otel-allocator/prehook/relabel.go

@@ -21,19 +21,23 @@ import (
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
 )
 
-type RelabelConfigTargetFilter struct {
+const (
+	relabelConfigTargetFilterName = "relabel-config"
+)
+
+type relabelConfigTargetFilter struct {
 	log        logr.Logger
 	relabelCfg map[string][]*relabel.Config
 }
 
-func NewRelabelConfigTargetFilter(log logr.Logger) Hook {
-	return &RelabelConfigTargetFilter{
+func newRelabelConfigTargetFilter(log logr.Logger) Hook {
+	return &relabelConfigTargetFilter{
 		log:        log,
 		relabelCfg: make(map[string][]*relabel.Config),
 	}
 }
 
-func (tf *RelabelConfigTargetFilter) Apply(targets map[string]*target.Item) map[string]*target.Item {
+func (tf *relabelConfigTargetFilter) Apply(targets map[string]*target.Item) map[string]*target.Item {
 	numTargets := len(targets)
 
 	// need to wait until relabelCfg is set
@@ -58,7 +62,7 @@ func (tf *RelabelConfigTargetFilter) Apply(targets map[string]*target.Item) map[
 	return targets
 }
 
-func (tf *RelabelConfigTargetFilter) SetConfig(cfgs map[string][]*relabel.Config) {
+func (tf *relabelConfigTargetFilter) SetConfig(cfgs map[string][]*relabel.Config) {
 	relabelCfgCopy := make(map[string][]*relabel.Config)
 	for key, val := range cfgs {
 		relabelCfgCopy[key] = tf.replaceRelabelConfig(val)
@@ -71,7 +75,7 @@ func (tf *RelabelConfigTargetFilter) SetConfig(cfgs map[string][]*relabel.Config
 // for why SHARD == 0 is a necessary substitution. Otherwise the keep action that uses this env variable,
 // would not match the regex and all targets end up dropped. Also note, $(SHARD) will always be 0 and it
 // does not make sense to read from the environment because it is never set in the allocator.
-func (tf *RelabelConfigTargetFilter) replaceRelabelConfig(cfg []*relabel.Config) []*relabel.Config {
+func (tf *relabelConfigTargetFilter) replaceRelabelConfig(cfg []*relabel.Config) []*relabel.Config {
 	for i := range cfg {
 		str := cfg[i].Regex.String()
 		if str == "$(SHARD)" {
@@ -82,7 +86,7 @@ func (tf *RelabelConfigTargetFilter) replaceRelabelConfig(cfg []*relabel.Config)
 	return cfg
 }
 
-func (tf *RelabelConfigTargetFilter) GetConfig() map[string][]*relabel.Config {
+func (tf *relabelConfigTargetFilter) GetConfig() map[string][]*relabel.Config {
 	relabelCfgCopy := make(map[string][]*relabel.Config)
 	for k, v := range tf.relabelCfg {
 		relabelCfgCopy[k] = v