Use celery app timezone

docs/config.rst

@@ -331,6 +331,16 @@ Enables showing time relative to the page refresh time in a more human-readable
 
 When enabled, timestamps will be shown as relative time such as "2 minutes ago" or "1 hour ago" instead of the exact timestamp.
 
+
+.. _browser_local_time:
+
+browser_local_time
+~~~~~~~~~~~~~~~~~~
+
+Default: False
+
+Show time in the browser's local timezone. If not specified, or set to `False`, the timezone of the Celery app is used.
+
 .. _persistent:
 
 persistent

docs/man.rst

@@ -55,6 +55,7 @@ OPTIONS
                                    basic auth
   --broker-api                     inspect broker e.g.
                                    http://guest:guest@localhost:15672/api/
+  --browser-local-time             show time in the browser's local TZ (default *False*)
   --ca-certs                       path to SSL certificate authority (CA) file
   --certfile                       path to SSL certificate file
   --conf                           flower configuration file path (default *flowerconfig.py*)

flower/options.py

@@ -61,6 +61,8 @@
        help="use custom task formatter")
 define("natural_time", type=bool, default=False,
        help="show time in relative format")
+define("browser_local_time", type=bool, default=False,
+       help="show time in the browser's local TZ")
 define("tasks_columns", type=str,
        default="name,uuid,state,args,kwargs,result,received,started,runtime,worker",
        help="slugs of columns on /tasks/ page, delimited by comma")

flower/static/js/flower.js

@@ -525,14 +525,18 @@ var flower = (function () {
     }
 
     function format_time(timestamp) {
-        var time = $('#time').val(),
-            prefix = time.startsWith('natural-time') ? 'natural-time' : 'time',
-            tz = time.substr(prefix.length + 1) || 'UTC';
+        var time = $('#time').val()
+        var prefix = time.startsWith('natural-time') ? 'natural-time' : 'time'
+        var tz = time.substr(prefix.length + 1) || moment.tz.guess(); // Use browser's local TZ if not set
+
+        var m = moment.unix(timestamp).tz(tz);
+        var fullTime = m.format('YYYY-MM-DD HH:mm:ss.SSS'); // full date/time without TZ
 
         if (prefix === 'natural-time') {
-            return moment.unix(timestamp).tz(tz).fromNow();
+            return '<span title="' + fullTime + ' (' + tz + ')">' + m.fromNow() + '</span>';
         }
-        return moment.unix(timestamp).tz(tz).format('YYYY-MM-DD HH:mm:ss.SSS');
+
+        return '<span title="' + m.fromNow() + ' (' + tz + ')">' + fullTime + '</span>';
     }
 
     function usesNaturalTime() {
@@ -929,8 +933,7 @@ var flower = (function () {
                             return format_time(data);
                         }
                         return '<time datetime="' + moment.unix(data).toISOString() +
-                            '" title="' + moment.unix(data).fromNow() + '">' +
-                            format_time(data) + '</time>';
+                            '">' + format_time(data) + '</time>';
                     }
                     return data;
                 }

flower/views/tasks.py

@@ -1,7 +1,10 @@
 import copy
 import logging
+from zoneinfo import ZoneInfo
 
 from tornado import web
+from tzlocal import get_localzone
+from celery.utils.time import LocalTimezone
 
 from ..utils.search import QuerySyntaxError
 from ..utils.tasks import as_dict, get_task_by_id, search_tasks
@@ -96,8 +99,25 @@ def get(self):
         capp = self.application.capp
 
         time = 'natural-time' if app.options.natural_time else 'time'
-        if capp.conf.timezone:
-            time += '-' + str(capp.conf.timezone)
+
+        if not app.options.browser_local_time:
+            # Append Celery app timezone in IANA format
+
+            timezone = None
+
+            if capp.timezone:
+                if isinstance(capp.timezone, LocalTimezone):
+                    try:
+                        timezone = get_localzone()
+                    except Exception as ex:
+                        logger.warning("Failed to retrieve local timezone (%s): %s", type(ex).__name__, ex)
+                else:
+                    timezone = capp.timezone
+
+            if timezone is None:
+                timezone = ZoneInfo("UTC")
+
+            time = f'{time}-{timezone}'
 
         self.render(
             "tasks.html",

requirements/default.txt

@@ -3,3 +3,4 @@ tornado>=6.5.7,<7.0.0
 prometheus_client>=0.8.0
 humanize
 pytz
+tzlocal

tests/unit/views/test_tasks.py

@@ -2,6 +2,7 @@
 import time
 
 from celery.events import Event
+from tzlocal import get_localzone
 
 from flower.events import EventsState
 from tests.unit import AsyncHTTPTestCase
@@ -343,3 +344,66 @@ def test_pagination(self):
         self.assertEqual('task2', tasks[0]['name'])
         self.assertEqual('456', tasks[0]['uuid'])
         self.assertEqual('worker1', tasks[0]['worker'])
+
+
+class TasksTimeZoneTest(AsyncHTTPTestCase):
+
+    def test_config_time_zone_is_utc(self):
+        del self._app.capp.timezone  # clear cached property
+        self._app.capp.conf.timezone = 'UTC'
+        self._app.capp.conf.enable_utc = False  # should be ignored
+        self._app.options.browser_local_time = False
+
+        r = self.get('/tasks')
+        self.assertEqual(200, r.code)
+        body = r.body.decode()
+        self.assertIn('time-UTC', body)
+
+    def test_config_time_zone_is_celery_local(self):
+        del self._app.capp.timezone  # clear cached property
+        self._app.capp.conf.timezone = 'Pacific/Chatham'
+        self._app.capp.conf.enable_utc = True  # should be ignored
+        self._app.options.browser_local_time = False
+
+        r = self.get('/tasks')
+        self.assertEqual(200, r.code)
+        body = r.body.decode()
+
+        self.assertIn('time-Pacific/Chatham', body)
+
+    def test_default_time_zone_is_utc(self):
+        del self._app.capp.timezone  # clear cached property
+        self._app.capp.conf.enable_utc = True
+        self._app.options.browser_local_time = False
+
+        r = self.get('/tasks')
+        self.assertEqual(200, r.code)
+        body = r.body.decode()
+        self.assertIn('time-UTC', body)
+
+    def test_default_time_zone_is_system_local(self):
+        del self._app.capp.timezone  # clear cached property
+        self._app.capp.conf.enable_utc = False
+        self._app.options.browser_local_time = False
+
+        try:
+            expected_tz = get_localzone()
+        except Exception:
+            expected_tz = None
+        if expected_tz is None:
+            expected_tz = 'UTC'
+
+        r = self.get('/tasks')
+        self.assertEqual(200, r.code)
+        body = r.body.decode()
+        self.assertIn(f'time-{expected_tz}', body)
+
+    def test_browser_local_time(self):
+        del self._app.capp.timezone  # clear cached property
+        self._app.capp.conf.timezone = 'Pacific/Chatham'
+        self._app.options.browser_local_time = True
+
+        r = self.get('/tasks')
+        self.assertEqual(200, r.code)
+        body = r.body.decode()
+        self.assertIn('value="time"', body)