acme-dns: allow the HTTP storage server to create the CNAME (#2437)

providers/dns/acmedns/acmedns.go

@@ -178,16 +178,26 @@ func (d *DNSProvider) register(ctx context.Context, domain, fqdn string) error {
 		return err
 	}
 
+	var cnameCreated bool
+
 	// Store the new account in the storage and call save to persist the data.
 	err = d.storage.Put(ctx, domain, newAcct)
 	if err != nil {
-		return err
+		cnameCreated = errors.Is(err, internal.ErrCNAMEAlreadyCreated)
+		if !cnameCreated {
+			return err
+		}
 	}
+
 	err = d.storage.Save(ctx)
 	if err != nil {
 		return err
 	}
 
+	if cnameCreated {
+		return nil
+	}
+
 	// Stop issuance by returning an error.
 	// The user needs to perform a manual one-time CNAME setup in their DNS zone
 	// to complete the setup of the new account we created.

providers/dns/acmedns/internal/http_storage.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -17,6 +18,8 @@ import (
 
 var _ goacmedns.Storage = (*HTTPStorage)(nil)
 
+var ErrCNAMEAlreadyCreated = errors.New("the CNAME has already been created")
+
 // HTTPStorage is an implementation of [acmedns.Storage] over HTTP.
 type HTTPStorage struct {
 	client  *http.Client
@@ -98,6 +101,11 @@ func (s *HTTPStorage) do(req *http.Request, result any) error {
 	}
 
 	if result == nil {
+		// Hack related to `Put`.
+		if resp.StatusCode == http.StatusCreated {
+			return ErrCNAMEAlreadyCreated
+		}
+
 		return nil
 	}
 

providers/dns/acmedns/internal/http_storage_test.go

@@ -137,3 +137,18 @@ func TestHTTPStorage_Put_error(t *testing.T) {
 	err := storage.Put(context.Background(), "example.com", account)
 	require.Error(t, err)
 }
+
+func TestHTTPStorage_Put_CNAME_created(t *testing.T) {
+	storage := setupTest(t, "POST /example.com", "", http.StatusCreated)
+
+	account := goacmedns.Account{
+		FullDomain: "foo.example.com",
+		SubDomain:  "foo",
+		Username:   "user",
+		Password:   "secret",
+		ServerURL:  "https://example.com",
+	}
+
+	err := storage.Put(context.Background(), "example.com", account)
+	require.ErrorIs(t, err, ErrCNAMEAlreadyCreated)
+}

providers/dns/acmedns/internal/readme.md

@@ -61,7 +61,9 @@ Endpoint: `POST <BaseURL>/<domain>`
 
 ### Response
 
-Response status code 200.
+Response status code:
+- 200: the process will be stopped to allow the user to create the CNAME.
+- 201: the process will continue without error (the CNAME should be created by the server)
 
 No expected body.