apps: Use GitHub API for generating the web app download link.

static/js/portico/landing-page.js

@@ -22,33 +22,13 @@ const hello_events = function () {
 };
 
 const apps_events = function () {
-    const ELECTRON_APP_VERSION = page_params.electron_app_version;
-    const ELECTRON_APP_URL_LINUX =
-        "https://github.com/zulip/zulip-desktop/releases/download/v" +
-        ELECTRON_APP_VERSION +
-        "/Zulip-" +
-        ELECTRON_APP_VERSION +
-        "-x86_64.AppImage";
-    const ELECTRON_APP_URL_MAC =
-        "https://github.com/zulip/zulip-desktop/releases/download/v" +
-        ELECTRON_APP_VERSION +
-        "/Zulip-" +
-        ELECTRON_APP_VERSION +
-        ".dmg";
-    const ELECTRON_APP_URL_WINDOWS =
-        "https://github.com/zulip/zulip-desktop/releases/download/v" +
-        ELECTRON_APP_VERSION +
-        "/Zulip-Web-Setup-" +
-        ELECTRON_APP_VERSION +
-        ".exe";
-
     const info = {
         windows: {
             image: "/static/images/landing-page/microsoft.png",
             alt: "Windows",
             description:
                 "Zulip for Windows is even better than Zulip on the web, with a cleaner look, tray integration, native notifications, and support for multiple Zulip accounts.",
-            link: ELECTRON_APP_URL_WINDOWS,
+            download_link: "/apps/download/windows",
             show_instructions: true,
             install_guide: "/help/desktop-app-install-guide",
             app_type: "desktop",
@@ -58,7 +38,7 @@ const apps_events = function () {
             alt: "macOS",
             description:
                 "Zulip on macOS is even better than Zulip on the web, with a cleaner look, tray integration, native notifications, and support for multiple Zulip accounts.",
-            link: ELECTRON_APP_URL_MAC,
+            download_link: "/apps/download/mac",
             show_instructions: true,
             install_guide: "/help/desktop-app-install-guide",
             app_type: "desktop",
@@ -84,7 +64,7 @@ const apps_events = function () {
             alt: "Linux",
             description:
                 "Zulip on the Linux desktop is even better than Zulip on the web, with a cleaner look, tray integration, native notifications, and support for multiple Zulip accounts.",
-            link: ELECTRON_APP_URL_LINUX,
+            download_link: "/apps/download/linux",
             show_instructions: true,
             install_guide: "/help/desktop-app-install-guide",
             app_type: "desktop",
@@ -127,7 +107,7 @@ const apps_events = function () {
 
         $(".info .platform").text(version_info.alt);
         $(".info .description").text(version_info.description);
-        $(".info .desktop-download-link").attr("href", version_info.link);
+        $(".info .desktop-download-link").attr("href", version_info.download_link);
         $(".download-from-google-play-store").attr("href", version_info.link);
         $(".download-from-apple-app-store").attr("href", version_info.link);
         $(".image img").attr("src", version_info.image);

version.py

@@ -12,7 +12,6 @@ if os.path.exists(zulip_git_version_file):
 LATEST_MAJOR_VERSION = "3.0"
 LATEST_RELEASE_VERSION = "3.0"
 LATEST_RELEASE_ANNOUNCEMENT = "https://blog.zulip.org/2020/07/16/zulip-3-0-released/"
-LATEST_DESKTOP_VERSION = "5.4.3"
 
 # Versions of the desktop app below DESKTOP_MINIMUM_VERSION will be
 # prevented from connecting to the Zulip server.  Versions above

zerver/lib/github.py

@@ -0,0 +1,48 @@
+import json
+import logging
+
+import requests
+
+from zerver.lib.cache import cache_with_key
+
+logger = logging.getLogger(__name__)
+
+def get_latest_github_release_version_for_repo(repo: str) -> str:
+    api_url = f"https://api.github.com/repos/zulip/{repo}/releases/latest"
+    try:
+        return requests.get(api_url).json()["tag_name"]
+    except (requests.RequestException, json.JSONDecodeError, KeyError):
+        logger.error("Unable to fetch the latest release version from GitHub %s", api_url)
+        return ""
+
+def verify_release_download_link(link: str) -> bool:
+    try:
+        requests.head(link).raise_for_status()
+        return True
+    except requests.RequestException:
+        logger.error("App download link is broken %s", link)
+        return False
+
+PLATFORM_TO_SETUP_FILE = {
+    "linux": "Zulip-{version}-x86_64.AppImage",
+    "mac": "Zulip-{version}.dmg",
+    "windows": "Zulip-Web-Setup-{version}.exe",
+}
+
+class InvalidPlatform(Exception):
+    pass
+
+@cache_with_key(lambda platform: f"download_link:{platform}", timeout=60*30)
+def get_latest_github_release_download_link_for_platform(platform: str) -> str:
+    if platform not in PLATFORM_TO_SETUP_FILE:
+        raise InvalidPlatform()
+
+    latest_version = get_latest_github_release_version_for_repo("zulip-desktop")
+    if latest_version:
+        if latest_version[0] in ["v", "V"]:
+            latest_version = latest_version[1:]
+        setup_file = PLATFORM_TO_SETUP_FILE[platform].format(version=latest_version)
+        link = f"https://github.com/zulip/zulip-desktop/releases/download/v{latest_version}/{setup_file}"
+        if verify_release_download_link(link):
+            return link
+    return "https://github.com/zulip/zulip-desktop/releases/latest"

zerver/tests/test_docs.py

@@ -471,6 +471,17 @@ class AppsPageTest(ZulipTestCase):
         html = result.content.decode('utf-8')
         self.assertIn('Apps for every platform.', html)
 
+    def test_app_download_link_view(self) -> None:
+        return_value = "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-Web-Setup-5.4.3.exe"
+        with mock.patch("zerver.views.portico.get_latest_github_release_download_link_for_platform", return_value=return_value) as m:
+            result = self.client_get("/apps/download/windows")
+            m.assert_called_once_with("windows")
+            self.assertEqual(result.status_code, 302)
+            self.assertTrue(result['Location'] == return_value)
+
+        result = self.client_get("/apps/download/plan9")
+        self.assertEqual(result.status_code, 404)
+
 class PrivacyTermsTest(ZulipTestCase):
     def test_custom_tos_template(self) -> None:
         response = self.client_get("/terms/")

zerver/tests/test_github.py

@@ -0,0 +1,64 @@
+import requests
+import responses
+
+from zerver.lib.cache import cache_delete
+from zerver.lib.github import InvalidPlatform, get_latest_github_release_download_link_for_platform
+from zerver.lib.test_classes import ZulipTestCase
+
+logger_string = "zerver.lib.github"
+
+class GitHubTestCase(ZulipTestCase):
+    @responses.activate
+    def test_get_latest_github_release_download_link_for_platform(self) -> None:
+        responses.add(responses.GET, "https://api.github.com/repos/zulip/zulip-desktop/releases/latest",
+                      json={"tag_name": "v5.4.3"}, status=200)
+
+        responses.add(responses.HEAD, "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-Web-Setup-5.4.3.exe",
+                      status=302)
+        self.assertEqual(
+            get_latest_github_release_download_link_for_platform("windows"),
+            "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-Web-Setup-5.4.3.exe"
+        )
+
+        responses.add(responses.HEAD, "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-5.4.3-x86_64.AppImage",
+                      status=302)
+        self.assertEqual(
+            get_latest_github_release_download_link_for_platform("linux"),
+            "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-5.4.3-x86_64.AppImage"
+        )
+
+        responses.add(responses.HEAD, "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-5.4.3.dmg", status=302)
+        self.assertEqual(
+            get_latest_github_release_download_link_for_platform("mac"),
+            "https://github.com/zulip/zulip-desktop/releases/download/v5.4.3/Zulip-5.4.3.dmg"
+        )
+
+        api_url = "https://api.github.com/repos/zulip/zulip-desktop/releases/latest"
+        responses.replace(responses.GET, api_url, body=requests.RequestException())
+        cache_delete("download_link:windows")
+        with self.assertLogs(logger_string, level='ERROR') as error_log:
+            self.assertEqual(
+                get_latest_github_release_download_link_for_platform("windows"),
+                "https://github.com/zulip/zulip-desktop/releases/latest"
+            )
+            self.assertEqual(error_log.output, [
+                f'ERROR:{logger_string}:Unable to fetch the latest release version from GitHub {api_url}'
+            ])
+
+        responses.replace(responses.GET, "https://api.github.com/repos/zulip/zulip-desktop/releases/latest",
+                          json={"tag_name": "5.4.4"}, status=200)
+        download_link = "https://github.com/zulip/zulip-desktop/releases/download/v5.4.4/Zulip-5.4.4-x86_64.AppImage"
+        responses.add(responses.HEAD, download_link, status=404)
+        cache_delete("download_link:linux")
+        with self.assertLogs(logger_string, level='ERROR') as error_log:
+            self.assertEqual(
+                get_latest_github_release_download_link_for_platform("linux"),
+                "https://github.com/zulip/zulip-desktop/releases/latest"
+            )
+
+            self.assertEqual(error_log.output, [
+                f'ERROR:{logger_string}:App download link is broken {download_link}'
+            ])
+
+        with self.assertRaises(InvalidPlatform):
+            get_latest_github_release_download_link_for_platform("plan9")

zerver/views/portico.py

@@ -6,9 +6,9 @@ from django.contrib.auth.views import redirect_to_login
 from django.http import HttpRequest, HttpResponse, HttpResponseRedirect
 from django.template.response import TemplateResponse
 
-from version import LATEST_DESKTOP_VERSION
 from zerver.context_processors import get_realm_from_request, latest_info_context
 from zerver.decorator import add_google_analytics
+from zerver.lib.github import InvalidPlatform, get_latest_github_release_download_link_for_platform
 from zerver.models import Realm
 
 
@@ -18,14 +18,16 @@ def apps_view(request: HttpRequest, platform: Optional[str] = None) -> HttpRespo
         return TemplateResponse(
             request,
             'zerver/apps.html',
-            context={
-                "page_params": {
-                    'electron_app_version': LATEST_DESKTOP_VERSION,
-                },
-            },
         )
     return HttpResponseRedirect('https://zulip.com/apps/', status=301)
 
+def app_download_link_redirect(request: HttpRequest, platform: str) -> HttpResponse:
+    try:
+        download_link = get_latest_github_release_download_link_for_platform(platform)
+        return HttpResponseRedirect(download_link, status=302)
+    except InvalidPlatform:
+        return TemplateResponse(request, "404.html", status=404)
+
 @add_google_analytics
 def plans_view(request: HttpRequest) -> HttpResponse:
     realm = get_realm_from_request(request)

zproject/urls.py

@@ -82,6 +82,7 @@ from zerver.views.message_flags import (
 from zerver.views.message_send import render_message_backend, send_message_backend, zcommand_backend
 from zerver.views.muting import update_muted_topic
 from zerver.views.portico import (
+    app_download_link_redirect,
     apps_view,
     hello_view,
     landing_view,
@@ -728,6 +729,7 @@ i18n_urls = [
     path('features/', landing_view, {'template_name': 'zerver/features.html'}),
     path('plans/', plans_view, name='plans'),
     path('apps/', apps_view),
+    path('apps/download/<platform>', app_download_link_redirect),
     path('apps/<platform>', apps_view),
     path('team/', team_view),
     path('history/', landing_view, {'template_name': 'zerver/history.html'}),