fix(helm-lint): Add HTTP/HTTPS URL support for json schema references

Signed-off-by: Isaiah Lewis <isaiah@roof12.com>

pkg/chart/v2/util/jsonschema.go

@@ -21,13 +21,53 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"net/http"
 	"strings"
+	"time"
 
 	"github.com/santhosh-tekuri/jsonschema/v6"
 
+	"helm.sh/helm/v4/internal/version"
+
 	chart "helm.sh/helm/v4/pkg/chart/v2"
 )
 
+// HTTPURLLoader implements a loader for HTTP/HTTPS URLs
+type HTTPURLLoader http.Client
+
+func (l *HTTPURLLoader) Load(urlStr string) (any, error) {
+	client := (*http.Client)(l)
+
+	req, err := http.NewRequest(http.MethodGet, urlStr, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create HTTP request for %s: %w", urlStr, err)
+	}
+	req.Header.Set("User-Agent", version.GetUserAgent())
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("HTTP request failed for %s: %w", urlStr, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("HTTP request to %s returned status %d (%s)", urlStr, resp.StatusCode, http.StatusText(resp.StatusCode))
+	}
+
+	return jsonschema.UnmarshalJSON(resp.Body)
+}
+
+// newHTTPURLLoader creates a HTTP URL loader with proxy support.
+func newHTTPURLLoader() *HTTPURLLoader {
+	httpLoader := HTTPURLLoader(http.Client{
+		Timeout: 15 * time.Second,
+		Transport: &http.Transport{
+			Proxy: http.ProxyFromEnvironment,
+		},
+	})
+	return &httpLoader
+}
+
 // ValidateAgainstSchema checks that values does not violate the structure laid out in schema
 func ValidateAgainstSchema(chrt *chart.Chart, values map[string]interface{}) error {
 	var sb strings.Builder
@@ -71,7 +111,15 @@ func ValidateAgainstSingleSchema(values Values, schemaJSON []byte) (reterr error
 	}
 	slog.Debug("unmarshalled JSON schema", "schema", schemaJSON)
 
+	// Configure compiler with loaders for different URL schemes
+	loader := jsonschema.SchemeURLLoader{
+		"file":  jsonschema.FileLoader{},
+		"http":  newHTTPURLLoader(),
+		"https": newHTTPURLLoader(),
+	}
+
 	compiler := jsonschema.NewCompiler()
+	compiler.UseLoader(loader)
 	err = compiler.AddResource("file:///values.schema.json", schema)
 	if err != nil {
 		return err

pkg/chart/v2/util/jsonschema_test.go

@@ -17,7 +17,10 @@ limitations under the License.
 package util
 
 import (
+	"net/http"
+	"net/http/httptest"
 	"os"
+	"strings"
 	"testing"
 
 	chart "helm.sh/helm/v4/pkg/chart/v2"
@@ -245,3 +248,40 @@ func TestValidateAgainstSchema2020Negative(t *testing.T) {
 		t.Errorf("Error string :\n`%s`\ndoes not match expected\n`%s`", errString, expectedErrString)
 	}
 }
+
+func TestHTTPURLLoader_Load(t *testing.T) {
+	// Test successful JSON schema loading
+	t.Run("successful load", func(t *testing.T) {
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(`{"type": "object", "properties": {"name": {"type": "string"}}}`))
+		}))
+		defer server.Close()
+
+		loader := newHTTPURLLoader()
+		result, err := loader.Load(server.URL)
+		if err != nil {
+			t.Fatalf("Expected no error, got: %v", err)
+		}
+		if result == nil {
+			t.Fatal("Expected result to be non-nil")
+		}
+	})
+
+	t.Run("HTTP error status", func(t *testing.T) {
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusNotFound)
+		}))
+		defer server.Close()
+
+		loader := newHTTPURLLoader()
+		_, err := loader.Load(server.URL)
+		if err == nil {
+			t.Fatal("Expected error for HTTP 404")
+		}
+		if !strings.Contains(err.Error(), "404") {
+			t.Errorf("Expected error message to contain '404', got: %v", err)
+		}
+	})
+}