feat(dns): add CLI commands to reserve, show, delete cluster domain

internal/dns/client.go

@@ -0,0 +1,118 @@
+package dns
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"strings"
+)
+
+// The dns package code is based on https://github.com/acorn-io/runtime/blob/main/pkg/dns.
+
+// Client handles interactions with the Uncloud DNS API service.
+type Client interface {
+	// ReserveDomain calls Uncloud DNS to reserve a new domain. It returns the domain, a token for authentication,
+	// and an error.
+	ReserveDomain(endpoint string) (string, string, error)
+}
+
+// ErrAuthNoDomain indicates that a request failed authentication because the domain was not found.
+// If encountered, a new domain needs to be reserved.
+var ErrAuthNoDomain = errors.New("the supplied domain failed authentication")
+
+// NewClient creates a new AcornDNS client
+func NewClient() Client {
+	return &client{
+		c: http.DefaultClient,
+	}
+}
+
+type client struct {
+	c *http.Client
+}
+
+func (c *client) ReserveDomain(endpoint string) (string, string, error) {
+	url := fmt.Sprintf("%s/%s", endpoint, "domains")
+
+	req, err := c.request(http.MethodPost, url, nil, "")
+	if err != nil {
+		return "", "", err
+	}
+
+	resp := &DomainResponse{}
+	err = c.do(req, resp)
+	if err != nil {
+		return "", "", err
+	}
+
+	domain := resp.Name
+	if strings.HasPrefix(domain, ".") {
+		domain = domain[1:]
+	}
+	return domain, resp.Token, nil
+}
+
+func (c *client) request(method string, url string, body io.Reader, token string) (*http.Request, error) {
+	req, err := http.NewRequest(method, url, body)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Add("Content-Type", "application/json")
+
+	if token != "" {
+		bearer := "Bearer " + token
+		req.Header.Add("Authorization", bearer)
+	}
+
+	return req, nil
+}
+
+func (c *client) do(req *http.Request, responseBody any) error {
+	slog.Debug("Making request to DNS service.", "method", req.Method, "url", req.URL)
+
+	resp, err := c.c.Do(req)
+	if err != nil {
+		return err
+	}
+
+	slog.Debug("Response code for request to DNS service.",
+		"method", req.Method, "url", req.URL, "code", resp.StatusCode)
+	// When err is nil, resp contains a non-nil resp.Body which must be closed.
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("read response body: %w", err)
+	}
+
+	if resp.StatusCode == http.StatusUnauthorized {
+		var authError AuthErrorResponse
+
+		err = json.Unmarshal(body, &authError)
+		if err != nil {
+			return fmt.Errorf("unmarshal auth error response: %w", err)
+		}
+
+		if authError.Data.NoDomain {
+			return ErrAuthNoDomain
+		}
+
+		return errors.New("authentication failed")
+	}
+
+	if code := resp.StatusCode; code < 200 || code > 300 {
+		return fmt.Errorf("unexpected response status code: %d", code)
+	}
+
+	if responseBody != nil {
+		err = json.Unmarshal(body, responseBody)
+		if err != nil {
+			return fmt.Errorf("unmarshal response body (%s): %w", string(body), err)
+		}
+	}
+
+	return nil
+}