fix: Testing of chromium distributed by grafana-image-renderer

* We need to do some basic test using chromium shipped by Grafana image renderer before using it. We were testing it using `--help` flag which does not exist on the application. If it works, it hangs which is not what we want.

* This commit fixes this test by using a command that returns upon successful execution. We also use a timeout just in case to avoid the command hanging in there forever.

* We also setup a special home directory for chromium and inject `XDG_CONFIG_HOME` and `XDG_CONFIG_HOME` env vars in chromium process. This avoids chromium attempting to create directories in read-only folders.

Signed-off-by: Mahendra Paipuri <mahendra.paipuri@gmail.com>

pkg/plugin/chrome/local.go

@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"slices"
+	"time"
 
 	"github.com/chromedp/chromedp"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/log"
@@ -15,7 +16,10 @@ import (
 )
 
 // Path to chrome executable.
-var chromeExec string
+var (
+	chromeExec    string
+	chromeHomeDir string
+)
 
 func init() {
 	// Get Grafana data path based on path of current executable
@@ -28,6 +32,12 @@ func init() {
 	// Now we attempt to get install_dir directory which is Grafana data path
 	dataPath := filepath.Dir(filepath.Dir(filepath.Dir(pluginExe)))
 
+	// Create a folder to use it as HOME for chrome process
+	homeDir := filepath.Join(dataPath, ".chrome")
+	if err := os.MkdirAll(homeDir, 0o750); err == nil {
+		chromeHomeDir = homeDir
+	}
+
 	// Walk through grafana-image-renderer plugin dir to find chrome executable
 	_ = filepath.Walk(filepath.Join(dataPath, "plugins", "grafana-image-renderer"),
 		func(path string, info fs.FileInfo, err error) error {
@@ -43,7 +53,13 @@ func init() {
 				// even a "usable" chrome (for instance chromium installed using snap on Ubuntu)
 				// exists.
 				// So, test the chromium before using it
-				if _, err := exec.Command(path, "--help").Output(); err == nil {
+				//
+				// Use a timeout to avoid indefinite hanging
+				ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+				defer cancel()
+
+				// This command should print an empty DOM and exit
+				if _, err := exec.CommandContext(ctx, path, "--headless", "--no-sandbox", "--disable-gpu", "--dump-dom").Output(); err == nil {
 					chromeExec = path
 				}
 
@@ -71,6 +87,12 @@ func NewLocalBrowserInstance(ctx context.Context, logger log.Logger, insecureSki
 		chromedp.DisableGPU,
 	)
 
+	// If we managed to create a home for chrome in a "writable" location, set it to chrome options
+	if chromeHomeDir != "" {
+		logger.Debug("created home directory for chromium process", "home", chromeHomeDir)
+		chromeOptions = append(chromeOptions, chromedp.Env("XDG_CONFIG_HOME="+chromeHomeDir, "XDG_CACHE_HOME="+chromeHomeDir))
+	}
+
 	// If chromExec is not empty we found chrome binary shipped by grafana-image-renderer
 	if chromeExec != "" {
 		logger.Info("chrome executable provided by grafana-image-renderer will be used", "chrome", chromeExec)

pkg/plugin/dashboard/panels_test.go

@@ -50,20 +50,6 @@ func TestDashboardFetchWithLocalChrome(t *testing.T) {
 	}
 
 	Convey("When fetching a Dashboard", t, func() {
-		// Get CWD
-		cwd, err := os.Getwd()
-
-		Convey("getting CWD should not error", func() {
-			So(err, ShouldBeNil)
-		})
-
-		// Read sample HTML file
-		data, err := os.ReadFile(filepath.Join(cwd, "testdata/dashboard.html"))
-
-		Convey("setup a dashboard HTML page should not error", func() {
-			So(err, ShouldBeNil)
-		})
-
 		chromeInstance, err := chrome.NewLocalBrowserInstance(context.Background(), log.NewNullLogger(), true)
 		defer chromeInstance.Close(log.NewNullLogger()) //nolint:staticcheck
 
@@ -76,6 +62,22 @@ func TestDashboardFetchWithLocalChrome(t *testing.T) {
 		requestCookie := ""
 
 		ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Get CWD
+			cwd, err := os.Getwd()
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+
+				return
+			}
+
+			// Read sample HTML file
+			data, err := os.ReadFile(filepath.Join(cwd, "testdata/dashboard.html"))
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+
+				return
+			}
+
 			muLock.Lock()
 			requestURI = append(requestURI, r.RequestURI)
 			requestCookie = r.Header.Get(backend.CookiesHeaderName)
@@ -149,20 +151,6 @@ func TestDashboardFetchWithRemoteChrome(t *testing.T) {
 	}
 
 	Convey("When fetching a Dashboard", t, func() {
-		// Get CWD
-		cwd, err := os.Getwd()
-
-		Convey("getting CWD should not error", func() {
-			So(err, ShouldBeNil)
-		})
-
-		// Read sample HTML file
-		data, err := os.ReadFile(filepath.Join(cwd, "testdata/dashboard.html"))
-
-		Convey("setup a dashboard HTML page should not error", func() {
-			So(err, ShouldBeNil)
-		})
-
 		chromeInstance, err := chrome.NewRemoteBrowserInstance(
 			context.Background(),
 			log.NewNullLogger(),
@@ -178,6 +166,22 @@ func TestDashboardFetchWithRemoteChrome(t *testing.T) {
 		requestCookie := ""
 
 		ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Get CWD
+			cwd, err := os.Getwd()
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+
+				return
+			}
+
+			// Read sample HTML file
+			data, err := os.ReadFile(filepath.Join(cwd, "testdata/dashboard.html"))
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+
+				return
+			}
+
 			muLock.Lock()
 			requestURI = append(requestURI, r.RequestURI)
 			requestCookie = r.Header.Get(backend.CookiesHeaderName)