Allow defining custom resource flags multiple times

docs/customresourcestate-metrics.md

@@ -9,12 +9,14 @@ A YAML configuration file described below is required to define your custom reso
 
 Two flags can be used:
 
- * `--custom-resource-state-config "inline yaml (see example)"` or
- * `--custom-resource-state-config-file /path/to/config.yaml`
+* `--custom-resource-state-config "inline yaml (see example)"` or
+* `--custom-resource-state-config-file /path/to/config.yaml`
 
-If both flags are provided, the inline configuration will take precedence.
+Both flags can be provided multiple times to load multiple configurations.
+When multiple entries for the same resource exist, kube-state-metrics will refuse to start.
+This includes configuration which refers to a different API version.
 
-In addition to specifying one of `--custom-resource-state-config*` flags, you should also add the custom resource *Kind*s in plural form to the list of exposed resources in the `--resources` flag. If you don't specify `--resources`, then all known custom resources configured in `--custom-resource-state-config-*` and all available default kubernetes objects will be taken into account by kube-state-metrics.
+In addition to specifying one of `--custom-resource-state-config*` flags, you should also add the custom resource *Kind*s in plural form to the list of exposed resources in the `--resources` flag. If you don't specify `--resources`, then all known custom resources configured in `--custom-resource-state-config*` and all available default kubernetes objects will be taken into account by kube-state-metrics.
 
 ```yaml
 apiVersion: apps/v1

main.go

@@ -53,8 +53,8 @@ func main() {
 	}
 
 	var factories []customresource.RegistryFactory
-	if config, set := resolveCustomResourceConfig(opts); set {
-		crf, err := customresourcestate.FromConfig(config)
+	if configs := resolveCustomResourceConfigs(opts); len(configs) > 0 {
+		crf, err := customresourcestate.FromConfigs(configs)
 		if err != nil {
 			klog.ErrorS(err, "Parsing from Custom Resource State Metrics file failed")
 			klog.FlushAndExit(klog.ExitFlushTimeout, 1)
@@ -69,17 +69,18 @@ func main() {
 	}
 }
 
-func resolveCustomResourceConfig(opts *options.Options) (customresourcestate.ConfigDecoder, bool) {
-	if s := opts.CustomResourceConfig; s != "" {
-		return yaml.NewDecoder(strings.NewReader(s)), true
+func resolveCustomResourceConfigs(opts *options.Options) []customresourcestate.ConfigDecoder {
+	decoders := []customresourcestate.ConfigDecoder{}
+	for _, s := range opts.CustomResourceConfigs {
+		decoders = append(decoders, yaml.NewDecoder(strings.NewReader(s)))
 	}
-	if file := opts.CustomResourceConfigFile; file != "" {
+	for _, file := range opts.CustomResourceConfigFiles {
 		f, err := os.Open(file)
 		if err != nil {
-			klog.ErrorS(err, "Custom Resource State Metrics file could not be opened")
+			klog.ErrorS(err, "Custom Resource State Metrics file could not be opened", "file", file)
 			klog.FlushAndExit(klog.ExitFlushTimeout, 1)
 		}
-		return yaml.NewDecoder(f), true
+		decoders = append(decoders, yaml.NewDecoder(f))
 	}
-	return nil, false
+	return decoders
 }

pkg/customresourcestate/config.go

@@ -161,9 +161,30 @@ type ConfigDecoder interface {
 	Decode(v interface{}) (err error)
 }
 
-// FromConfig decodes a configuration source into a slice of customresource.RegistryFactory that are ready to use.
-func FromConfig(decoder ConfigDecoder) (factories []customresource.RegistryFactory, err error) {
+// FromConfigs decodes a configuration source into a slice of customresource.RegistryFactory that are ready to use.
+func FromConfigs(decoders []ConfigDecoder) ([]customresource.RegistryFactory, error) {
+	factoriesIndex := map[string]bool{}
+	var factories []customresource.RegistryFactory
+	for _, decoder := range decoders {
+		fs, err := fromConfig(decoder)
+		if err != nil {
+			return nil, err
+		}
+		for _, f := range fs {
+			if _, ok := factoriesIndex[f.Name()]; ok {
+				return nil, fmt.Errorf("found multiple custom resource configurations for the same resource %s", f.Name())
+			}
+			factoriesIndex[f.Name()] = true
+			factories = append(factories, f)
+		}
+	}
+
+	return factories, nil
+}
+
+func fromConfig(decoder ConfigDecoder) ([]customresource.RegistryFactory, error) {
 	var crconfig Metrics
+	var factories []customresource.RegistryFactory
 	if err := decoder.Decode(&crconfig); err != nil {
 		return nil, fmt.Errorf("failed to parse Custom Resource State metrics: %w", err)
 	}

pkg/options/options.go

@@ -54,8 +54,8 @@ type Options struct {
 
 	UseAPIServerCache bool
 
-	CustomResourceConfig     string
-	CustomResourceConfigFile string
+	CustomResourceConfigs     []string
+	CustomResourceConfigFiles []string
 
 	flags *pflag.FlagSet
 }
@@ -115,8 +115,8 @@ func (o *Options) AddFlags() {
 	o.flags.BoolVarP(&o.Version, "version", "", false, "kube-state-metrics build version information")
 	o.flags.BoolVar(&o.EnableGZIPEncoding, "enable-gzip-encoding", false, "Gzip responses when requested by clients via 'Accept-Encoding: gzip' header.")
 
-	o.flags.StringVar(&o.CustomResourceConfig, "custom-resource-state-config", "", "Inline Custom Resource State Metrics config YAML (experimental)")
-	o.flags.StringVar(&o.CustomResourceConfigFile, "custom-resource-state-config-file", "", "Path to a Custom Resource State Metrics config file (experimental)")
+	o.flags.StringArrayVar(&o.CustomResourceConfigs, "custom-resource-state-config", []string{}, "Inline Custom Resource State Metrics config YAML (experimental)")
+	o.flags.StringArrayVar(&o.CustomResourceConfigFiles, "custom-resource-state-config-file", []string{}, "Path to a Custom Resource State Metrics config file (experimental)")
 }
 
 // Parse parses the flag definitions from the argument list.