feat(oci): oci helm support [r8s-361] (#787)

api/http/proxy/factory/gitlab/client.go

@@ -0,0 +1,130 @@
+package gitlab
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/segmentio/encoding/json"
+	"oras.land/oras-go/v2/registry/remote/retry"
+)
+
+// Repository represents a GitLab registry repository
+type Repository struct {
+	ID        int    `json:"id"`
+	Name      string `json:"name"`
+	Path      string `json:"path"`
+	ProjectID int    `json:"project_id"`
+	Location  string `json:"location"`
+	CreatedAt string `json:"created_at"`
+	Status    string `json:"status"`
+}
+
+// Client represents a GitLab API client
+type Client struct {
+	httpClient *http.Client
+	baseURL    string
+}
+
+// NewClient creates a new GitLab API client
+// it currently is an http client because only GetRegistryRepositoryNames is needed (oras supports other commands).
+// if we need to support other commands, consider using the gitlab client library.
+func NewClient(baseURL, token string) *Client {
+	return &Client{
+		httpClient: NewHTTPClient(token),
+		baseURL:    baseURL,
+	}
+}
+
+// GetRegistryRepositoryNames fetches registry repository names for a given project.
+// It's a small http client wrapper instead of using the gitlab client library because listing repositories is the only known operation that isn't directly supported by oras
+func (c *Client) GetRegistryRepositoryNames(ctx context.Context, projectID int) ([]string, error) {
+	url := fmt.Sprintf("%s/api/v4/projects/%d/registry/repositories", c.baseURL, projectID)
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GitLab API returned status %d: %s", resp.StatusCode, resp.Status)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	var repositories []Repository
+	if err := json.Unmarshal(body, &repositories); err != nil {
+		return nil, fmt.Errorf("failed to parse response: %w", err)
+	}
+
+	// Extract repository names
+	names := make([]string, len(repositories))
+	for i, repo := range repositories {
+		// the full path is required for further repo operations
+		names[i] = repo.Path
+	}
+
+	return names, nil
+}
+
+type Transport struct {
+	httpTransport *http.Transport
+}
+
+// NewTransport returns a pointer to a new instance of Transport that implements the HTTP Transport
+// interface for proxying requests to the Gitlab API.
+func NewTransport() *Transport {
+	return &Transport{
+		httpTransport: &http.Transport{},
+	}
+}
+
+// RoundTrip is the implementation of the http.RoundTripper interface
+func (transport *Transport) RoundTrip(request *http.Request) (*http.Response, error) {
+	token := request.Header.Get("Private-Token")
+	if token == "" {
+		return nil, errors.New("no gitlab token provided")
+	}
+
+	r, err := http.NewRequest(request.Method, request.URL.String(), request.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	r.Header.Set("Private-Token", token)
+	return transport.httpTransport.RoundTrip(r)
+}
+
+// NewHTTPClient creates a new HTTP client configured for GitLab API requests
+func NewHTTPClient(token string) *http.Client {
+	return &http.Client{
+		Transport: &tokenTransport{
+			token:     token,
+			transport: retry.NewTransport(&http.Transport{}), // Use ORAS retry transport for consistent rate limiting and error handling
+		},
+		Timeout: 1 * time.Minute,
+	}
+}
+
+// tokenTransport automatically adds the Private-Token header to requests
+type tokenTransport struct {
+	token     string
+	transport http.RoundTripper
+}
+
+func (t *tokenTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	req.Header.Set("Private-Token", t.token)
+	return t.transport.RoundTrip(req)
+}