Move to PatternFly Elements and lit

PFE uses lit, so it makes sense to just use that for the main
application as well. Web components are pretty much React built into the
web platform, and lit adds some convenience around that.

This is mostly a demo -- for real Cockpit pages, PF Elements is still
missing too many components.

Install query-selector-shadow-dom to enable testlib's shiny new support
for traversing selectors through shadow DOMs from
cockpit-project/cockpit#21233

.eslintrc.json

@@ -4,12 +4,11 @@
         "browser": true,
         "es6": true
     },
-    "extends": ["eslint:recommended", "standard", "standard-jsx", "standard-react"],
+    "extends": ["eslint:recommended", "standard"],
     "parserOptions": {
         "ecmaVersion": "2022",
         "sourceType": "module"
     },
-    "plugins": ["react", "react-hooks"],
     "rules": {
         "indent": ["error", 4,
             {
@@ -22,23 +21,15 @@
         "no-var": "error",
         "lines-between-class-members": ["error", "always", { "exceptAfterSingleLine": true }],
         "prefer-promise-reject-errors": ["error", { "allowEmptyReject": true }],
-        "react/jsx-indent": ["error", 4],
         "semi": ["error", "always", { "omitLastInOneLineBlock": true }],
 
-        "react-hooks/rules-of-hooks": "error",
-        "react-hooks/exhaustive-deps": "error",
-
         "camelcase": "off",
         "comma-dangle": "off",
         "curly": "off",
         "jsx-quotes": "off",
         "key-spacing": "off",
         "no-console": "off",
         "quotes": "off",
-        "react/jsx-curly-spacing": "off",
-        "react/jsx-indent-props": "off",
-        "react/jsx-no-useless-fragment": "error",
-        "react/prop-types": "off",
         "space-before-function-paren": "off",
         "standard/no-callback-literal": "off"
     },

Makefile

@@ -114,6 +114,12 @@ devel-uninstall:
 print-version:
 	@echo "$(VERSION)"
 
+# required for running integration tests
+TEST_NPMS = \
+	node_modules/query-selector-shadow-dom \
+	$(NULL)
+
+
 dist: $(TARFILE)
 	@ls -1 $(TARFILE)
 
@@ -125,8 +131,8 @@ $(TARFILE): export NODE_ENV=production
 $(TARFILE): $(DIST_TEST) $(SPEC)
 	if type appstream-util >/dev/null 2>&1; then appstream-util validate-relax --nonet *.metainfo.xml; fi
 	tar --xz $(TAR_ARGS) -cf $(TARFILE) --transform 's,^,$(RPM_NAME)/,' \
-		--exclude packaging/$(SPEC).in --exclude node_modules \
-		$$(git ls-files) $(COCKPIT_REPO_FILES) $(NODE_MODULES_TEST) $(SPEC) dist/
+		--exclude packaging/$(SPEC).in \
+		$$(git ls-files) $(COCKPIT_REPO_FILES) $(NODE_MODULES_TEST) $(SPEC) $(TEST_NPMS) dist/
 
 $(NODE_CACHE): $(NODE_MODULES_TEST)
 	tar --xz $(TAR_ARGS) -cf $@ node_modules

package.json

@@ -18,8 +18,6 @@
     "stylelint:fix": "stylelint --fix src/*{.css,scss}"
   },
   "devDependencies": {
-    "@types/react": "18.3.12",
-    "@types/react-dom": "18.3.1",
     "@typescript-eslint/eslint-plugin": "8.13.0",
     "argparse": "2.0.1",
     "esbuild": "0.24.0",
@@ -30,16 +28,14 @@
     "eslint": "8.57.1",
     "eslint-config-standard": "17.1.0",
     "eslint-config-standard-jsx": "11.0.0",
-    "eslint-config-standard-react": "13.0.0",
     "eslint-plugin-import": "2.31.0",
     "eslint-plugin-node": "11.1.0",
     "eslint-plugin-promise": "6.6.0",
-    "eslint-plugin-react": "7.37.2",
-    "eslint-plugin-react-hooks": "4.6.2",
     "gettext-parser": "8.0.0",
     "glob": "11.0.0",
     "htmlparser": "1.7.7",
     "jed": "1.1.1",
+    "query-selector-shadow-dom": "1.0.1",
     "qunit": "2.22.0",
     "sass": "1.80.3",
     "stylelint": "16.10.0",
@@ -50,11 +46,7 @@
     "typescript": "5.6.3"
   },
   "dependencies": {
-    "@patternfly/patternfly": "5.4.2",
-    "@patternfly/react-core": "5.4.8",
-    "@patternfly/react-icons": "5.4.2",
-    "@patternfly/react-styles": "5.4.1",
-    "react": "18.3.1",
-    "react-dom": "18.3.1"
+    "@patternfly/elements": "4.0.2",
+    "lit": "3.2.1"
   }
 }

src/app.scss

@@ -1,5 +1,6 @@
-@use "page.scss";
+// requires PF5, needs counterpart for PFE
+// @use "page.scss";
 
-p {
-    font-weight: bold;
+.running-on {
+    color: green;
 }

src/app.tsx

@@ -1,7 +1,7 @@
 /*
  * This file is part of Cockpit.
  *
- * Copyright (C) 2017 Red Hat, Inc.
+ * Copyright (C) 2024 Red Hat, Inc.
  *
  * Cockpit is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as published by
@@ -17,32 +17,30 @@
  * along with Cockpit; If not, see <http://www.gnu.org/licenses/>.
  */
 
-import React, { useEffect, useState } from 'react';
-import { Alert } from "@patternfly/react-core/dist/esm/components/Alert/index.js";
-import { Card, CardBody, CardTitle } from "@patternfly/react-core/dist/esm/components/Card/index.js";
+import { html, LitElement } from 'lit';
+import { customElement, state } from 'lit/decorators.js';
+
+import '@patternfly/elements/pf-card/pf-card.js';
 
 import cockpit from 'cockpit';
 
 const _ = cockpit.gettext;
 
-export const Application = () => {
-    const [hostname, setHostname] = useState(_("Unknown"));
+@customElement('ct-application')
+export class Application extends LitElement {
+    @state() private accessor hostname = _("Unknown");
 
-    useEffect(() => {
+    connectedCallback() {
+        super.connectedCallback();
         const hostname = cockpit.file('/etc/hostname');
-        hostname.watch(content => setHostname(content?.trim() ?? ""));
-        return hostname.close;
-    }, []);
+        hostname.watch(content => { this.hostname = content?.trim() ?? "" });
+    }
 
-    return (
-        <Card>
-            <CardTitle>Starter Kit</CardTitle>
-            <CardBody>
-                <Alert
-                    variant="info"
-                    title={ cockpit.format(_("Running on $0"), hostname) }
-                />
-            </CardBody>
-        </Card>
-    );
-};
+    render() {
+        return html`
+            <pf-card>
+                <h1 slot="header">Starter Kit</h1>
+                <p class="running-on">${cockpit.format(_("Running on $0"), this.hostname)}</p>
+            </pf-card>`;
+    }
+}

src/index.html

@@ -29,6 +29,6 @@
 </head>
 
 <body>
-    <div id="app"></div>
+    <ct-application />
 </body>
 </html>

src/index.tsx

@@ -1,7 +1,7 @@
 /*
  * This file is part of Cockpit.
  *
- * Copyright (C) 2017 Red Hat, Inc.
+ * Copyright (C) 2024 Red Hat, Inc.
  *
  * Cockpit is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as published by
@@ -17,16 +17,9 @@
  * along with Cockpit; If not, see <http://www.gnu.org/licenses/>.
  */
 
-import React from 'react';
-import { createRoot } from 'react-dom/client';
+// import "cockpit-dark-theme"; // doesn't work for PFE
 
-import "cockpit-dark-theme";
+import './app.jsx';
 
-import { Application } from './app.jsx';
-
-import "patternfly/patternfly-5-cockpit.scss";
+// import "patternfly/patternfly-5-cockpit.scss"; // does not apply to PFE
 import './app.scss';
-
-document.addEventListener("DOMContentLoaded", () => {
-    createRoot(document.getElementById("app")!).render(<Application />);
-});

test/check-application

@@ -18,16 +18,16 @@ class TestApplication(testlib.MachineCase):
 
         self.login_and_go("/starter-kit")
         # verify expected heading
-        b.wait_text(".pf-v5-c-card__title", "Starter Kit")
+        b.wait_text("pf-card [slot='header']", "Starter Kit")
 
         # verify expected host name
         hostname = m.execute("cat /etc/hostname").strip()
-        b.wait_in_text(".pf-v5-c-alert__title", "Running on " + hostname)
+        b.wait_in_text("pf-card .running-on", "Running on " + hostname)
 
         # change current hostname
         self.write_file("/etc/hostname", "new-" + hostname)
         # verify new hostname name
-        b.wait_in_text(".pf-v5-c-alert__title", "Running on new-" + hostname)
+        b.wait_in_text("pf-card .running-on", "Running on new-" + hostname)
 
         # change language to German
         b.switch_to_top()
@@ -46,7 +46,7 @@ class TestApplication(testlib.MachineCase):
         b.go("/starter-kit")
         b.enter_page("/starter-kit")
         # page label (from js) should be translated
-        b.wait_in_text(".pf-v5-c-alert__title", "Läuft auf")
+        b.wait_in_text("pf-card .running-on", "Läuft auf")
 
 
 if __name__ == '__main__':

tsconfig.json

@@ -3,7 +3,6 @@
     "allowJs": true,
     "checkJs": true,
     "exactOptionalPropertyTypes": true,
-    "jsx": "react",
     "lib": [
       "dom",
       "es2020"