Disabled on webservers in 047817b6b0, it has since lingered in
configuration, as well as running (to no effect) every minute on the
loadbalancer.
Remove the vestiges of its configuration.
Zulip has had a small use of WebSockets (specifically, for the code
path of sending messages, via the webapp only) since ~2013. We
originally added this use of WebSockets in the hope that the latency
benefits of doing so would allow us to avoid implementing a markdown
local echo; they were not. Further, HTTP/2 may have eliminated the
latency difference we hoped to exploit by using WebSockets in any
case.
While we’d originally imagined using WebSockets for other endpoints,
there was never a good justification for moving more components to the
WebSockets system.
This WebSockets code path had a lot of downsides/complexity,
including:
* The messy hack involving constructing an emulated request object to
hook into doing Django requests.
* The `message_senders` queue processor system, which increases RAM
needs and must be provisioned independently from the rest of the
server).
* A duplicate check_send_receive_time Nagios test specific to
WebSockets.
* The requirement for users to have their firewalls/NATs allow
WebSocket connections, and a setting to disable them for networks
where WebSockets don’t work.
* Dependencies on the SockJS family of libraries, which has at times
been poorly maintained, and periodically throws random JavaScript
exceptions in our production environments without a deep enough
traceback to effectively investigate.
* A total of about 1600 lines of our code related to the feature.
* Increased load on the Tornado system, especially around a Zulip
server restart, and especially for large installations like
zulipchat.com, resulting in extra delay before messages can be sent
again.
As detailed in
https://github.com/zulip/zulip/pull/12862#issuecomment-536152397, it
appears that removing WebSockets moderately increases the time it
takes for the `send_message` API query to return from the server, but
does not significantly change the time between when a message is sent
and when it is received by clients. We don’t understand the reason
for that change (suggesting the possibility of a measurement error),
and even if it is a real change, we consider that potential small
latency regression to be acceptable.
If we later want WebSockets, we’ll likely want to just use Django
Channels.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
While this is a different system than I'd written up in #8004, I think
this is a better solution to the general problem of cron jobs to run
on just one server.
Fixes#8004.
This code empirically doesn't work. It's not entirely clear why, even
having done quite a bit of debugging; partly because the code is quite
convoluted, and because it shows the symptoms of people making changes
over time without really understanding how it was supposed to work.
Moreover, this code targets an old version of the APNs provider API.
Apple deprecated that in 2015, in favor of a shiny new one which uses
HTTP/2 to meet the same needs for concurrency and scale that the old
one had to do a bunch of ad-hoc protocol design for.
So, rip this code out. We'll build a pathway to the new API from
scratch; it's not that complicated.
This consists of the `zulip_ops::stats` Puppet class, which has apparently
not been used since 2014, and a number of files that I believe were
only used for that. Also a couple of tiny loose ends in other files.
These are no longer useful, with our spiffy new analytics framework,
and we haven't in fact been using them for some time, while the
`active-user-stats` cron job does cause regular mail from cron.
Just delete them.
- Add websocket client to create connection with SockJS websocket server.
It contains callback method to launch after connection setup.
- Add '--websocket' parameter to 'check_send_receive_time' script to
check websocket connection.
- Add testing websocket connection to production installation checking.
- Add cronjob to launch websocket connection nagios test.
This makes it possible for Zulip Nagios monitoring to check for
problems impacting the websockets sending code path, which is what all
web users use.
This allows the actual nagios work involved with
check_send_receive_time nagios checks to be done by an unprivileged
"nagios" user rather than the "zulip" user.
The old "zulip_internal" name was from back when Zulip, Inc. had two
distributions of Zulip, the enterprise distribution in puppet/zulip/
and the "internal" SAAS distribution in puppet/zulip_internal. I
think the name is a bit confusing in the new fully open-source Zulip
work, so we're replacing it with "zulip_ops". I don't think the new
name is perfect, but it's better.
In the following commits, we'll delete a bunch of pieces of Zulip,
Inc.'s infrastructure that don't exist anymore and thus are no longer
useful (e.g. the old Trac configuration), with the goal of cleaning
the repository of as much unnecessary content as possible.
Alex Vandiver
Vishnu KS
Anders Kaseorg
Tim Abbott
Greg Price
Reid Barton
K.Kanakhin
Anders Kaseorg
Tim Abbott