feat(client): add timeout to fetchResource to prevent hangs (#2322)

client/go/outline/fetch.go

@@ -17,16 +17,22 @@ package outline
 import (
 	"io"
 	"net/http"
+	"time"
 
 	"github.com/Jigsaw-Code/outline-apps/client/go/outline/platerrors"
 )
 
+const fetchTimeout = 10 * time.Second
+
 // fetchResource fetches a resource from the given URL.
 //
 // The function makes an HTTP GET request to the specified URL and returns the response body as a
 // string. If the request fails or the server returns a non-2xx status code, an error is returned.
 func fetchResource(url string) (string, error) {
-	resp, err := http.Get(url)
+	client := &http.Client{
+		Timeout: fetchTimeout,
+	}
+	resp, err := client.Get(url)
 	if err != nil {
 		return "", platerrors.PlatformError{
 			Code:    platerrors.FetchConfigFailed,

client/go/outline/fetch_test.go

@@ -19,6 +19,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 
 	"github.com/Jigsaw-Code/outline-apps/client/go/outline/platerrors"
 	"github.com/stretchr/testify/require"
@@ -100,3 +101,29 @@ func TestFetchResource_BodyReadError(t *testing.T) {
 	require.Equal(t, platerrors.FetchConfigFailed, perr.Code)
 	require.Error(t, perr.Cause)
 }
+
+func TestFetchResource_Timeout(t *testing.T) {
+	const (
+		MaxFetchWaitTime = 12 * time.Second
+		ServerDelay      = 20 * time.Second
+	)
+
+	testDone := make(chan bool)
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		select {
+		case <-time.After(ServerDelay):
+			w.WriteHeader(http.StatusNoContent)
+		case <-testDone:
+		}
+	}))
+	defer server.Close()
+
+	start := time.Now()
+	content, err := fetchResource(server.URL)
+	duration := time.Since(start)
+	testDone <- true
+
+	require.LessOrEqual(t, duration, MaxFetchWaitTime, "fetchResource should time out in 10s")
+	require.Error(t, err, "fetchResource should return a non-nil timeout error")
+	require.Empty(t, content)
+}