pkg/apis/externaldns/types.go
func (cfg *Config) ParseFlags(args []string) error {
	app := kingpin.New("external-dns", "ExternalDNS synchronizes exposed Kubernetes Services and Ingresses with DNS providers.\n\nNote that all flags may be replaced with env vars - `--flag` -> `EXTERNAL_DNS_FLAG=1` or `--flag value` -> `EXTERNAL_DNS_FLAG=value`")
	app.Version(Version)
	app.DefaultEnvars()

	// Flags related to Kubernetes
	app.Flag("master", "The Kubernetes API server to connect to (default: auto-detect)").Default(defaultConfig.Master).StringVar(&cfg.Master)
	app.Flag("kubeconfig", "Retrieve target cluster configuration from a Kubernetes configuration file (default: auto-detect)").Default(defaultConfig.KubeConfig).StringVar(&cfg.KubeConfig)
	app.Flag("request-timeout", "Request timeout when calling Kubernetes APIs. 0s means no timeout").Default(defaultConfig.RequestTimeout.String()).DurationVar(&cfg.RequestTimeout)

	// Flags related to Istio
	app.Flag("istio-ingress-gateway", "The fully-qualified name of the Istio ingress gateway service. Flag can be specified multiple times (default: istio-system/istio-ingressgateway)").Default("istio-system/istio-ingressgateway").StringsVar(&cfg.IstioIngressGatewayServices)

	// Flags related to processing sources
	app.Flag("source", "The resource types that are queried for endpoints; specify multiple times for multiple sources (required, options: service, ingress, fake, connector, istio-gateway, crd").Required().PlaceHolder("source").EnumsVar(&cfg.Sources, "service", "ingress", "istio-gateway", "fake", "connector", "crd")
	app.Flag("namespace", "Limit sources of endpoints to a specific namespace (default: all namespaces)").Default(defaultConfig.Namespace).StringVar(&cfg.Namespace)
	app.Flag("annotation-filter", "Filter sources managed by external-dns via annotation using label selector semantics (default: all sources)").Default(defaultConfig.AnnotationFilter).StringVar(&cfg.AnnotationFilter)
	app.Flag("fqdn-template", "A templated string that's used to generate DNS names from sources that don't define a hostname themselves, or to add a hostname suffix when paired with the fake source (optional). Accepts comma separated list for multiple global FQDN.").Default(defaultConfig.FQDNTemplate).StringVar(&cfg.FQDNTemplate)
	app.Flag("combine-fqdn-annotation", "Combine FQDN template and Annotations instead of overwriting").BoolVar(&cfg.CombineFQDNAndAnnotation)
	app.Flag("ignore-hostname-annotation", "Ignore hostname annotation when generating DNS names, valid only when using fqdn-template is set (optional, default: false)").BoolVar(&cfg.IgnoreHostnameAnnotation)
	app.Flag("compatibility", "Process annotation semantics from legacy implementations (optional, options: mate, molecule)").Default(defaultConfig.Compatibility).EnumVar(&cfg.Compatibility, "", "mate", "molecule")
	app.Flag("publish-internal-services", "Allow external-dns to publish DNS records for ClusterIP services (optional)").BoolVar(&cfg.PublishInternal)
	app.Flag("publish-host-ip", "Allow external-dns to publish host-ip for headless services (optional)").BoolVar(&cfg.PublishHostIP)
	app.Flag("connector-source-server", "The server to connect for connector source, valid only when using connector source").Default(defaultConfig.ConnectorSourceServer).StringVar(&cfg.ConnectorSourceServer)
	app.Flag("crd-source-apiversion", "API version of the CRD for crd source, e.g. `externaldns.k8s.io/v1alpha1`, valid only when using crd source").Default(defaultConfig.CRDSourceAPIVersion).StringVar(&cfg.CRDSourceAPIVersion)
	app.Flag("crd-source-kind", "Kind of the CRD for the crd source in API group and version specified by crd-source-apiversion").Default(defaultConfig.CRDSourceKind).StringVar(&cfg.CRDSourceKind)
	app.Flag("service-type-filter", "The service types to take care about (default: all, expected: ClusterIP, NodePort, LoadBalancer or ExternalName)").StringsVar(&cfg.ServiceTypeFilter)

	// Flags related to providers
	app.Flag("provider", "The DNS provider where the DNS records will be created (required, options: aws, aws-sd, google, azure, cloudflare, rcodezero, digitalocean, dnsimple, infoblox, dyn, designate, coredns, skydns, inmemory, pdns, oci, exoscale, linode, rfc2136, ns1)").Required().PlaceHolder("provider").EnumVar(&cfg.Provider, "aws", "aws-sd", "google", "azure", "alibabacloud", "cloudflare", "rcodezero", "digitalocean", "dnsimple", "infoblox", "dyn", "designate", "coredns", "skydns", "inmemory", "pdns", "oci", "exoscale", "linode", "rfc2136", "ns1")
	app.Flag("domain-filter", "Limit possible target zones by a domain suffix; specify multiple times for multiple domains (optional)").Default("").StringsVar(&cfg.DomainFilter)
	app.Flag("zone-id-filter", "Filter target zones by hosted zone id; specify multiple times for multiple zones (optional)").Default("").StringsVar(&cfg.ZoneIDFilter)
	app.Flag("google-project", "When using the Google provider, current project is auto-detected, when running on GCP. Specify other project with this. Must be specified when running outside GCP.").Default(defaultConfig.GoogleProject).StringVar(&cfg.GoogleProject)
	app.Flag("alibaba-cloud-config-file", "When using the Alibaba Cloud provider, specify the Alibaba Cloud configuration file (required when --provider=alibabacloud").Default(defaultConfig.AlibabaCloudConfigFile).StringVar(&cfg.AlibabaCloudConfigFile)
	app.Flag("alibaba-cloud-zone-type", "When using the Alibaba Cloud provider, filter for zones of this type (optional, options: public, private)").Default(defaultConfig.AlibabaCloudZoneType).EnumVar(&cfg.AlibabaCloudZoneType, "", "public", "private")
	app.Flag("aws-zone-type", "When using the AWS provider, filter for zones of this type (optional, options: public, private)").Default(defaultConfig.AWSZoneType).EnumVar(&cfg.AWSZoneType, "", "public", "private")
	app.Flag("aws-zone-tags", "When using the AWS provider, filter for zones with these tags").Default("").StringsVar(&cfg.AWSZoneTagFilter)
	app.Flag("aws-assume-role", "When using the AWS provider, assume this IAM role. Useful for hosted zones in another AWS account. Specify the full ARN, e.g. `arn:aws:iam::123455567:role/external-dns` (optional)").Default(defaultConfig.AWSAssumeRole).StringVar(&cfg.AWSAssumeRole)
	app.Flag("aws-batch-change-size", "When using the AWS provider, set the maximum number of changes that will be applied in each batch.").Default(strconv.Itoa(defaultConfig.AWSBatchChangeSize)).IntVar(&cfg.AWSBatchChangeSize)
	app.Flag("aws-batch-change-interval", "When using the AWS provider, set the interval between batch changes.").Default(defaultConfig.AWSBatchChangeInterval.String()).DurationVar(&cfg.AWSBatchChangeInterval)
	app.Flag("aws-evaluate-target-health", "When using the AWS provider, set whether to evaluate the health of a DNS target (default: enabled, disable with --no-aws-evaluate-target-health)").Default(strconv.FormatBool(defaultConfig.AWSEvaluateTargetHealth)).BoolVar(&cfg.AWSEvaluateTargetHealth)
	app.Flag("aws-api-retries", "When using the AWS provider, set the maximum number of retries for API calls before giving up.").Default(strconv.Itoa(defaultConfig.AWSAPIRetries)).IntVar(&cfg.AWSAPIRetries)
	app.Flag("azure-config-file", "When using the Azure provider, specify the Azure configuration file (required when --provider=azure").Default(defaultConfig.AzureConfigFile).StringVar(&cfg.AzureConfigFile)
	app.Flag("azure-resource-group", "When using the Azure provider, override the Azure resource group to use (optional)").Default(defaultConfig.AzureResourceGroup).StringVar(&cfg.AzureResourceGroup)
	app.Flag("cloudflare-proxied", "When using the Cloudflare provider, specify if the proxy mode must be enabled (default: disabled)").BoolVar(&cfg.CloudflareProxied)
	app.Flag("cloudflare-zones-per-page", "When using the Cloudflare provider, specify how many zones per page listed, max. possible 50 (default: 50)").Default(strconv.Itoa(defaultConfig.CloudflareZonesPerPage)).IntVar(&cfg.CloudflareZonesPerPage)
	app.Flag("infoblox-grid-host", "When using the Infoblox provider, specify the Grid Manager host (required when --provider=infoblox)").Default(defaultConfig.InfobloxGridHost).StringVar(&cfg.InfobloxGridHost)
	app.Flag("infoblox-wapi-port", "When using the Infoblox provider, specify the WAPI port (default: 443)").Default(strconv.Itoa(defaultConfig.InfobloxWapiPort)).IntVar(&cfg.InfobloxWapiPort)
	app.Flag("infoblox-wapi-username", "When using the Infoblox provider, specify the WAPI username (default: admin)").Default(defaultConfig.InfobloxWapiUsername).StringVar(&cfg.InfobloxWapiUsername)
	app.Flag("infoblox-wapi-password", "When using the Infoblox provider, specify the WAPI password (required when --provider=infoblox)").Default(defaultConfig.InfobloxWapiPassword).StringVar(&cfg.InfobloxWapiPassword)
	app.Flag("infoblox-wapi-version", "When using the Infoblox provider, specify the WAPI version (default: 2.3.1)").Default(defaultConfig.InfobloxWapiVersion).StringVar(&cfg.InfobloxWapiVersion)
	app.Flag("infoblox-ssl-verify", "When using the Infoblox provider, specify whether to verify the SSL certificate (default: true, disable with --no-infoblox-ssl-verify)").Default(strconv.FormatBool(defaultConfig.InfobloxSSLVerify)).BoolVar(&cfg.InfobloxSSLVerify)
	app.Flag("infoblox-view", "DNS view (default: \"\")").Default(defaultConfig.InfobloxView).StringVar(&cfg.InfobloxView)
	app.Flag("dyn-customer-name", "When using the Dyn provider, specify the Customer Name").Default("").StringVar(&cfg.DynCustomerName)
	app.Flag("dyn-username", "When using the Dyn provider, specify the Username").Default("").StringVar(&cfg.DynUsername)
	app.Flag("dyn-password", "When using the Dyn provider, specify the pasword").Default("").StringVar(&cfg.DynPassword)
	app.Flag("dyn-min-ttl", "Minimal TTL (in seconds) for records. This value will be used if the provided TTL for a service/ingress is lower than this.").IntVar(&cfg.DynMinTTLSeconds)
	app.Flag("oci-config-file", "When using the OCI provider, specify the OCI configuration file (required when --provider=oci").Default(defaultConfig.OCIConfigFile).StringVar(&cfg.OCIConfigFile)
	app.Flag("rcodezero-txt-encrypt", "When using the Rcodezero provider with txt registry option, set if TXT rrs are encrypted (default: false)").Default(strconv.FormatBool(defaultConfig.RcodezeroTXTEncrypt)).BoolVar(&cfg.RcodezeroTXTEncrypt)

	app.Flag("inmemory-zone", "Provide a list of pre-configured zones for the inmemory provider; specify multiple times for multiple zones (optional)").Default("").StringsVar(&cfg.InMemoryZones)
	app.Flag("pdns-server", "When using the PowerDNS/PDNS provider, specify the URL to the pdns server (required when --provider=pdns)").Default(defaultConfig.PDNSServer).StringVar(&cfg.PDNSServer)
	app.Flag("pdns-api-key", "When using the PowerDNS/PDNS provider, specify the API key to use to authorize requests (required when --provider=pdns)").Default(defaultConfig.PDNSAPIKey).StringVar(&cfg.PDNSAPIKey)
	app.Flag("pdns-tls-enabled", "When using the PowerDNS/PDNS provider, specify whether to use TLS (default: false, requires --tls-ca, optionally specify --tls-client-cert and --tls-client-cert-key)").Default(strconv.FormatBool(defaultConfig.PDNSTLSEnabled)).BoolVar(&cfg.PDNSTLSEnabled)

	// Flags related to TLS communication
	app.Flag("tls-ca", "When using TLS communication, the path to the certificate authority to verify server communications (optionally specify --tls-client-cert for two-way TLS)").Default(defaultConfig.TLSCA).StringVar(&cfg.TLSCA)
	app.Flag("tls-client-cert", "When using TLS communication, the path to the certificate to present as a client (not required for TLS)").Default(defaultConfig.TLSClientCert).StringVar(&cfg.TLSClientCert)
	app.Flag("tls-client-cert-key", "When using TLS communication, the path to the certificate key to use with the client certificate (not required for TLS)").Default(defaultConfig.TLSClientCertKey).StringVar(&cfg.TLSClientCertKey)

	app.Flag("exoscale-endpoint", "Provide the endpoint for the Exoscale provider").Default(defaultConfig.ExoscaleEndpoint).StringVar(&cfg.ExoscaleEndpoint)
	app.Flag("exoscale-apikey", "Provide your API Key for the Exoscale provider").Default(defaultConfig.ExoscaleAPIKey).StringVar(&cfg.ExoscaleAPIKey)
	app.Flag("exoscale-apisecret", "Provide your API Secret for the Exoscale provider").Default(defaultConfig.ExoscaleAPISecret).StringVar(&cfg.ExoscaleAPISecret)

	// Flags related to RFC2136 provider
	app.Flag("rfc2136-host", "When using the RFC2136 provider, specify the host of the DNS server").Default(defaultConfig.RFC2136Host).StringVar(&cfg.RFC2136Host)
	app.Flag("rfc2136-port", "When using the RFC2136 provider, specify the port of the DNS server").Default(strconv.Itoa(defaultConfig.RFC2136Port)).IntVar(&cfg.RFC2136Port)
	app.Flag("rfc2136-zone", "When using the RFC2136 provider, specify the zone entry of the DNS server to use").Default(defaultConfig.RFC2136Zone).StringVar(&cfg.RFC2136Zone)
	app.Flag("rfc2136-insecure", "When using the RFC2136 provider, specify whether to attach TSIG or not (default: false, requires --rfc2136-tsig-keyname and rfc2136-tsig-secret)").Default(strconv.FormatBool(defaultConfig.RFC2136Insecure)).BoolVar(&cfg.RFC2136Insecure)
	app.Flag("rfc2136-tsig-keyname", "When using the RFC2136 provider, specify the TSIG key to attached to DNS messages (required when --rfc2136-insecure=false)").Default(defaultConfig.RFC2136TSIGKeyName).StringVar(&cfg.RFC2136TSIGKeyName)
	app.Flag("rfc2136-tsig-secret", "When using the RFC2136 provider, specify the TSIG (base64) value to attached to DNS messages (required when --rfc2136-insecure=false)").Default(defaultConfig.RFC2136TSIGSecret).StringVar(&cfg.RFC2136TSIGSecret)
	app.Flag("rfc2136-tsig-secret-alg", "When using the RFC2136 provider, specify the TSIG (base64) value to attached to DNS messages (required when --rfc2136-insecure=false)").Default(defaultConfig.RFC2136TSIGSecretAlg).StringVar(&cfg.RFC2136TSIGSecretAlg)
	app.Flag("rfc2136-tsig-axfr", "When using the RFC2136 provider, specify the TSIG (base64) value to attached to DNS messages (required when --rfc2136-insecure=false)").BoolVar(&cfg.RFC2136TAXFR)

	// Flags related to policies
	app.Flag("policy", "Modify how DNS records are synchronized between sources and providers (default: sync, options: sync, upsert-only)").Default(defaultConfig.Policy).EnumVar(&cfg.Policy, "sync", "upsert-only")

	// Flags related to the registry
	app.Flag("registry", "The registry implementation to use to keep track of DNS record ownership (default: txt, options: txt, noop, aws-sd)").Default(defaultConfig.Registry).EnumVar(&cfg.Registry, "txt", "noop", "aws-sd")
	app.Flag("txt-owner-id", "When using the TXT registry, a name that identifies this instance of ExternalDNS (default: default)").Default(defaultConfig.TXTOwnerID).StringVar(&cfg.TXTOwnerID)
	app.Flag("txt-prefix", "When using the TXT registry, a custom string that's prefixed to each ownership DNS record (optional)").Default(defaultConfig.TXTPrefix).StringVar(&cfg.TXTPrefix)

	// Flags related to the main control loop
	app.Flag("txt-cache-interval", "The interval between cache synchronizations in duration format (default: disabled)").Default(defaultConfig.TXTCacheInterval.String()).DurationVar(&cfg.TXTCacheInterval)
	app.Flag("interval", "The interval between two consecutive synchronizations in duration format (default: 1m)").Default(defaultConfig.Interval.String()).DurationVar(&cfg.Interval)
	app.Flag("once", "When enabled, exits the synchronization loop after the first iteration (default: disabled)").BoolVar(&cfg.Once)
	app.Flag("dry-run", "When enabled, prints DNS record changes rather than actually performing them (default: disabled)").BoolVar(&cfg.DryRun)

	// Miscellaneous flags
	app.Flag("log-format", "The format in which log messages are printed (default: text, options: text, json)").Default(defaultConfig.LogFormat).EnumVar(&cfg.LogFormat, "text", "json")
	app.Flag("metrics-address", "Specify where to serve the metrics and health check endpoint (default: :7979)").Default(defaultConfig.MetricsAddress).StringVar(&cfg.MetricsAddress)
	app.Flag("log-level", "Set the level of logging. (default: info, options: panic, debug, info, warning, error, fatal").Default(defaultConfig.LogLevel).EnumVar(&cfg.LogLevel, allLogLevelsAsStrings()...)

	_, err := app.Parse(args)
	if err != nil {
		return err
	}

	return nil
}
func (cfg *Config) ParseFlags(args []string) error {
	app := kingpin.New("external-dns", "ExternalDNS synchronizes exposed Kubernetes Services and Ingresses with DNS providers.\n\nNote that all flags may be replaced with env vars - `--flag` -> `EXTERNAL_DNS_FLAG=1` or `--flag value` -> `EXTERNAL_DNS_FLAG=value`")
	app.Version(Version)
	app.DefaultEnvars()

	// Flags related to Kubernetes
	app.Flag("master", "The Kubernetes API server to connect to (default: auto-detect)").Default(defaultConfig.Master).StringVar(&cfg.Master)
	app.Flag("kubeconfig", "Retrieve target cluster configuration from a Kubernetes configuration file (default: auto-detect)").Default(defaultConfig.KubeConfig).StringVar(&cfg.KubeConfig)
	app.Flag("request-timeout", "Request timeout when calling Kubernetes APIs. 0s means no timeout").Default(defaultConfig.RequestTimeout.String()).DurationVar(&cfg.RequestTimeout)

	// Flags related to Istio
	app.Flag("istio-ingress-gateway", "The fully-qualified name of the Istio ingress gateway service. Flag can be specified multiple times (default: istio-system/istio-ingressgateway)").Default("istio-system/istio-ingressgateway").StringsVar(&cfg.IstioIngressGatewayServices)

	// Flags related to processing sources
	app.Flag("source", "The resource types that are queried for endpoints; specify multiple times for multiple sources (required, options: service, ingress, fake, connector, istio-gateway, crd").Required().PlaceHolder("source").EnumsVar(&cfg.Sources, "service", "ingress", "istio-gateway", "fake", "connector", "crd")
	app.Flag("namespace", "Limit sources of endpoints to a specific namespace (default: all namespaces)").Default(defaultConfig.Namespace).StringVar(&cfg.Namespace)
	app.Flag("annotation-filter", "Filter sources managed by external-dns via annotation using label selector semantics (default: all sources)").Default(defaultConfig.AnnotationFilter).StringVar(&cfg.AnnotationFilter)
	app.Flag("fqdn-template", "A templated string that's used to generate DNS names from sources that don't define a hostname themselves, or to add a hostname suffix when paired with the fake source (optional). Accepts comma separated list for multiple global FQDN.").Default(defaultConfig.FQDNTemplate).StringVar(&cfg.FQDNTemplate)
	app.Flag("combine-fqdn-annotation", "Combine FQDN template and Annotations instead of overwriting").BoolVar(&cfg.CombineFQDNAndAnnotation)
	app.Flag("ignore-hostname-annotation", "Ignore hostname annotation when generating DNS names, valid only when using fqdn-template is set (optional, default: false)").BoolVar(&cfg.IgnoreHostnameAnnotation)
	app.Flag("compatibility", "Process annotation semantics from legacy implementations (optional, options: mate, molecule)").Default(defaultConfig.Compatibility).EnumVar(&cfg.Compatibility, "", "mate", "molecule")
	app.Flag("publish-internal-services", "Allow external-dns to publish DNS records for ClusterIP services (optional)").BoolVar(&cfg.PublishInternal)
	app.Flag("publish-host-ip", "Allow external-dns to publish host-ip for headless services (optional)").BoolVar(&cfg.PublishHostIP)
	app.Flag("connector-source-server", "The server to connect for connector source, valid only when using connector source").Default(defaultConfig.ConnectorSourceServer).StringVar(&cfg.ConnectorSourceServer)
	app.Flag("crd-source-apiversion", "API version of the CRD for crd source, e.g. `externaldns.k8s.io/v1alpha1`, valid only when using crd source").Default(defaultConfig.CRDSourceAPIVersion).StringVar(&cfg.CRDSourceAPIVersion)
	app.Flag("crd-source-kind", "Kind of the CRD for the crd source in API group and version specified by crd-source-apiversion").Default(defaultConfig.CRDSourceKind).StringVar(&cfg.CRDSourceKind)
	app.Flag("service-type-filter", "The service types to take care about (default: all, expected: ClusterIP, NodePort, LoadBalancer or ExternalName)").StringsVar(&cfg.ServiceTypeFilter)

	// Flags related to providers
	app.Flag("provider", "The DNS provider where the DNS records will be created (required, options: aws, aws-sd, google, azure, cloudflare, rcodezero, digitalocean, dnsimple, infoblox, dyn, designate, coredns, skydns, inmemory, pdns, oci, exoscale, linode, rfc2136, ns1)").Required().PlaceHolder("provider").EnumVar(&cfg.Provider, "aws", "aws-sd", "google", "azure", "alibabacloud", "cloudflare", "rcodezero", "digitalocean", "dnsimple", "infoblox", "dyn", "designate", "coredns", "skydns", "inmemory", "pdns", "oci", "exoscale", "linode", "rfc2136", "ns1")
	app.Flag("domain-filter", "Limit possible target zones by a domain suffix; specify multiple times for multiple domains (optional)").Default("").StringsVar(&cfg.DomainFilter)
	app.Flag("zone-id-filter", "Filter target zones by hosted zone id; specify multiple times for multiple zones (optional)").Default("").StringsVar(&cfg.ZoneIDFilter)
	app.Flag("google-project", "When using the Google provider, current project is auto-detected, when running on GCP. Specify other project with this. Must be specified when running outside GCP.").Default(defaultConfig.GoogleProject).StringVar(&cfg.GoogleProject)
	app.Flag("alibaba-cloud-config-file", "When using the Alibaba Cloud provider, specify the Alibaba Cloud configuration file (required when --provider=alibabacloud").Default(defaultConfig.AlibabaCloudConfigFile).StringVar(&cfg.AlibabaCloudConfigFile)
	app.Flag("alibaba-cloud-zone-type", "When using the Alibaba Cloud provider, filter for zones of this type (optional, options: public, private)").Default(defaultConfig.AlibabaCloudZoneType).EnumVar(&cfg.AlibabaCloudZoneType, "", "public", "private")
	app.Flag("aws-zone-type", "When using the AWS provider, filter for zones of this type (optional, options: public, private)").Default(defaultConfig.AWSZoneType).EnumVar(&cfg.AWSZoneType, "", "public", "private")
	app.Flag("aws-zone-tags", "When using the AWS provider, filter for zones with these tags").Default("").StringsVar(&cfg.AWSZoneTagFilter)
	app.Flag("aws-assume-role", "When using the AWS provider, assume this IAM role. Useful for hosted zones in another AWS account. Specify the full ARN, e.g. `arn:aws:iam::123455567:role/external-dns` (optional)").Default(defaultConfig.AWSAssumeRole).StringVar(&cfg.AWSAssumeRole)
	app.Flag("aws-batch-change-size", "When using the AWS provider, set the maximum number of changes that will be applied in each batch.").Default(strconv.Itoa(defaultConfig.AWSBatchChangeSize)).IntVar(&cfg.AWSBatchChangeSize)
	app.Flag("aws-batch-change-interval", "When using the AWS provider, set the interval between batch changes.").Default(defaultConfig.AWSBatchChangeInterval.String()).DurationVar(&cfg.AWSBatchChangeInterval)
	app.Flag("aws-evaluate-target-health", "When using the AWS provider, set whether to evaluate the health of a DNS target (default: enabled, disable with --no-aws-evaluate-target-health)").Default(strconv.FormatBool(defaultConfig.AWSEvaluateTargetHealth)).BoolVar(&cfg.AWSEvaluateTargetHealth)
	app.Flag("aws-api-retries", "When using the AWS provider, set the maximum number of retries for API calls before giving up.").Default(strconv.Itoa(defaultConfig.AWSAPIRetries)).IntVar(&cfg.AWSAPIRetries)
	app.Flag("azure-config-file", "When using the Azure provider, specify the Azure configuration file (required when --provider=azure").Default(defaultConfig.AzureConfigFile).StringVar(&cfg.AzureConfigFile)
	app.Flag("azure-resource-group", "When using the Azure provider, override the Azure resource group to use (optional)").Default(defaultConfig.AzureResourceGroup).StringVar(&cfg.AzureResourceGroup)
	app.Flag("cloudflare-proxied", "When using the Cloudflare provider, specify if the proxy mode must be enabled (default: disabled)").BoolVar(&cfg.CloudflareProxied)
	app.Flag("cloudflare-zones-per-page", "When using the Cloudflare provider, specify how many zones per page listed, max. possible 50 (default: 50)").Default(strconv.Itoa(defaultConfig.CloudflareZonesPerPage)).IntVar(&cfg.CloudflareZonesPerPage)
	app.Flag("infoblox-grid-host", "When using the Infoblox provider, specify the Grid Manager host (required when --provider=infoblox)").Default(defaultConfig.InfobloxGridHost).StringVar(&cfg.InfobloxGridHost)
	app.Flag("infoblox-wapi-port", "When using the Infoblox provider, specify the WAPI port (default: 443)").Default(strconv.Itoa(defaultConfig.InfobloxWapiPort)).IntVar(&cfg.InfobloxWapiPort)
	app.Flag("infoblox-wapi-username", "When using the Infoblox provider, specify the WAPI username (default: admin)").Default(defaultConfig.InfobloxWapiUsername).StringVar(&cfg.InfobloxWapiUsername)
	app.Flag("infoblox-wapi-password", "When using the Infoblox provider, specify the WAPI password (required when --provider=infoblox)").Default(defaultConfig.InfobloxWapiPassword).StringVar(&cfg.InfobloxWapiPassword)
	app.Flag("infoblox-wapi-version", "When using the Infoblox provider, specify the WAPI version (default: 2.3.1)").Default(defaultConfig.InfobloxWapiVersion).StringVar(&cfg.InfobloxWapiVersion)
	app.Flag("infoblox-ssl-verify", "When using the Infoblox provider, specify whether to verify the SSL certificate (default: true, disable with --no-infoblox-ssl-verify)").Default(strconv.FormatBool(defaultConfig.InfobloxSSLVerify)).BoolVar(&cfg.InfobloxSSLVerify)
	app.Flag("infoblox-view", "DNS view (default: \"\")").Default(defaultConfig.InfobloxView).StringVar(&cfg.InfobloxView)
	app.Flag("dyn-customer-name", "When using the Dyn provider, specify the Customer Name").Default("").StringVar(&cfg.DynCustomerName)
	app.Flag("dyn-username", "When using the Dyn provider, specify the Username").Default("").StringVar(&cfg.DynUsername)
	app.Flag("dyn-password", "When using the Dyn provider, specify the pasword").Default("").StringVar(&cfg.DynPassword)
	app.Flag("dyn-min-ttl", "Minimal TTL (in seconds) for records. This value will be used if the provided TTL for a service/ingress is lower than this.").IntVar(&cfg.DynMinTTLSeconds)
	app.Flag("oci-config-file", "When using the OCI provider, specify the OCI configuration file (required when --provider=oci").Default(defaultConfig.OCIConfigFile).StringVar(&cfg.OCIConfigFile)
	app.Flag("rcodezero-txt-encrypt", "When using the Rcodezero provider with txt registry option, set if TXT rrs are encrypted (default: false)").Default(strconv.FormatBool(defaultConfig.RcodezeroTXTEncrypt)).BoolVar(&cfg.RcodezeroTXTEncrypt)

	app.Flag("inmemory-zone", "Provide a list of pre-configured zones for the inmemory provider; specify multiple times for multiple zones (optional)").Default("").StringsVar(&cfg.InMemoryZones)
	app.Flag("pdns-server", "When using the PowerDNS/PDNS provider, specify the URL to the pdns server (required when --provider=pdns)").Default(defaultConfig.PDNSServer).StringVar(&cfg.PDNSServer)
	app.Flag("pdns-api-key", "When using the PowerDNS/PDNS provider, specify the API key to use to authorize requests (required when --provider=pdns)").Default(defaultConfig.PDNSAPIKey).StringVar(&cfg.PDNSAPIKey)
	app.Flag("pdns-tls-enabled", "When using the PowerDNS/PDNS provider, specify whether to use TLS (default: false, requires --tls-ca, optionally specify --tls-client-cert and --tls-client-cert-key)").Default(strconv.FormatBool(defaultConfig.PDNSTLSEnabled)).BoolVar(&cfg.PDNSTLSEnabled)

	// Flags related to TLS communication
	app.Flag("tls-ca", "When using TLS communication, the path to the certificate authority to verify server communications (optionally specify --tls-client-cert for two-way TLS)").Default(defaultConfig.TLSCA).StringVar(&cfg.TLSCA)
	app.Flag("tls-client-cert", "When using TLS communication, the path to the certificate to present as a client (not required for TLS)").Default(defaultConfig.TLSClientCert).StringVar(&cfg.TLSClientCert)
	app.Flag("tls-client-cert-key", "When using TLS communication, the path to the certificate key to use with the client certificate (not required for TLS)").Default(defaultConfig.TLSClientCertKey).StringVar(&cfg.TLSClientCertKey)

	app.Flag("exoscale-endpoint", "Provide the endpoint for the Exoscale provider").Default(defaultConfig.ExoscaleEndpoint).StringVar(&cfg.ExoscaleEndpoint)
	app.Flag("exoscale-apikey", "Provide your API Key for the Exoscale provider").Default(defaultConfig.ExoscaleAPIKey).StringVar(&cfg.ExoscaleAPIKey)
	app.Flag("exoscale-apisecret", "Provide your API Secret for the Exoscale provider").Default(defaultConfig.ExoscaleAPISecret).StringVar(&cfg.ExoscaleAPISecret)

	// Flags related to RFC2136 provider
	app.Flag("rfc2136-host", "When using the RFC2136 provider, specify the host of the DNS server").Default(defaultConfig.RFC2136Host).StringVar(&cfg.RFC2136Host)
	app.Flag("rfc2136-port", "When using the RFC2136 provider, specify the port of the DNS server").Default(strconv.Itoa(defaultConfig.RFC2136Port)).IntVar(&cfg.RFC2136Port)
	app.Flag("rfc2136-zone", "When using the RFC2136 provider, specify the zone entry of the DNS server to use").Default(defaultConfig.RFC2136Zone).StringVar(&cfg.RFC2136Zone)
	app.Flag("rfc2136-insecure", "When using the RFC2136 provider, specify whether to attach TSIG or not (default: false, requires --rfc2136-tsig-keyname and rfc2136-tsig-secret)").Default(strconv.FormatBool(defaultConfig.RFC2136Insecure)).BoolVar(&cfg.RFC2136Insecure)
	app.Flag("rfc2136-tsig-keyname", "When using the RFC2136 provider, specify the TSIG key to attached to DNS messages (required when --rfc2136-insecure=false)").Default(defaultConfig.RFC2136TSIGKeyName).StringVar(&cfg.RFC2136TSIGKeyName)
	app.Flag("rfc2136-tsig-secret", "When using the RFC2136 provider, specify the TSIG (base64) value to attached to DNS messages (required when --rfc2136-insecure=false)").Default(defaultConfig.RFC2136TSIGSecret).StringVar(&cfg.RFC2136TSIGSecret)
	app.Flag("rfc2136-tsig-secret-alg", "When using the RFC2136 provider, specify the TSIG (base64) value to attached to DNS messages (required when --rfc2136-insecure=false)").Default(defaultConfig.RFC2136TSIGSecretAlg).StringVar(&cfg.RFC2136TSIGSecretAlg)
	app.Flag("rfc2136-tsig-axfr", "When using the RFC2136 provider, specify the TSIG (base64) value to attached to DNS messages (required when --rfc2136-insecure=false)").BoolVar(&cfg.RFC2136TAXFR)

	// Flags related to policies
	app.Flag("policy", "Modify how DNS records are synchronized between sources and providers (default: sync, options: sync, upsert-only)").Default(defaultConfig.Policy).EnumVar(&cfg.Policy, "sync", "upsert-only")

	// Flags related to the registry
	app.Flag("registry", "The registry implementation to use to keep track of DNS record ownership (default: txt, options: txt, noop, aws-sd)").Default(defaultConfig.Registry).EnumVar(&cfg.Registry, "txt", "noop", "aws-sd")
	app.Flag("txt-owner-id", "When using the TXT registry, a name that identifies this instance of ExternalDNS (default: default)").Default(defaultConfig.TXTOwnerID).StringVar(&cfg.TXTOwnerID)
	app.Flag("txt-prefix", "When using the TXT registry, a custom string that's prefixed to each ownership DNS record (optional)").Default(defaultConfig.TXTPrefix).StringVar(&cfg.TXTPrefix)

	// Flags related to the main control loop
	app.Flag("txt-cache-interval", "The interval between cache synchronizations in duration format (default: disabled)").Default(defaultConfig.TXTCacheInterval.String()).DurationVar(&cfg.TXTCacheInterval)
	app.Flag("interval", "The interval between two consecutive synchronizations in duration format (default: 1m)").Default(defaultConfig.Interval.String()).DurationVar(&cfg.Interval)
	app.Flag("once", "When enabled, exits the synchronization loop after the first iteration (default: disabled)").BoolVar(&cfg.Once)
	app.Flag("dry-run", "When enabled, prints DNS record changes rather than actually performing them (default: disabled)").BoolVar(&cfg.DryRun)

	// Miscellaneous flags
	app.Flag("log-format", "The format in which log messages are printed (default: text, options: text, json)").Default(defaultConfig.LogFormat).EnumVar(&cfg.LogFormat, "text", "json")
	app.Flag("metrics-address", "Specify where to serve the metrics and health check endpoint (default: :7979)").Default(defaultConfig.MetricsAddress).StringVar(&cfg.MetricsAddress)
	app.Flag("log-level", "Set the level of logging. (default: info, options: panic, debug, info, warning, error, fatal").Default(defaultConfig.LogLevel).EnumVar(&cfg.LogLevel, allLogLevelsAsStrings()...)

	_, err := app.Parse(args)
	if err != nil {
		return err
	}

	return nil
}
// ParseFlags adds and parses flags from command line