add cloudflare and documentation

internal/app/config/DNSProvider.go

@@ -7,6 +7,7 @@ type DNSProviderConfig struct {
 	HuaweiCloud  `json:"HuaweiCloud,omitempty"`
 	WestCN       `json:"WestCN,omitempty"`
 	RainYun      `json:"RainYun,omitempty"`
+	Cloudflare   `json:"Cloudflare,omitempty"`
 	Dode         `json:"Dode,omitempty"`
 }
 
@@ -40,3 +41,9 @@ type RainYun struct {
 type Dode struct {
 	Token string `json:"Token,omitempty"`
 }
+
+type Cloudflare struct {
+	APIToken string `json:"APIToken,omitempty"`
+	APIKey   string `json:"APIKey,omitempty"`
+	Email    string `json:"Email,omitempty"`
+}

internal/app/config/DNSProviderMethod.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"github.com/go-acme/lego/v4/challenge"
+	"github.com/go-acme/lego/v4/providers/dns/cloudflare"
 	"github.com/go-acme/lego/v4/providers/dns/alidns"
 	"github.com/go-acme/lego/v4/providers/dns/dode"
 	"github.com/go-acme/lego/v4/providers/dns/huaweicloud"
@@ -52,6 +53,24 @@ func (rain RainYun) Provider() (challenge.Provider, error) {
 	return p, err
 }
 
+func (cloud Cloudflare) Provider() (challenge.Provider, error) {
+	cfg := cloudflare.NewDefaultConfig()
+	// lego's cloudflare.Config uses AuthToken / AuthKey / AuthEmail / ZoneToken
+	if cloud.APIToken != "" {
+		cfg.AuthToken = cloud.APIToken
+	}
+	if cloud.APIKey != "" {
+		cfg.AuthKey = cloud.APIKey
+	}
+	if cloud.Email != "" {
+		cfg.AuthEmail = cloud.Email
+	}
+	// support ZoneToken if provided in future (keep empty if not set)
+	// if you add ZoneToken to the config struct, map it here: cfg.ZoneToken = cloud.ZoneToken
+	p, err := cloudflare.NewDNSProviderConfig(cfg)
+	return p, err
+}
+
 func (Dode Dode) Provider() (challenge.Provider, error) {
 	cfg := dode.NewDefaultConfig()
 	cfg.Token = Dode.Token