Restarting the uwsgi processes by way of supervisor opens a window
during which nginx 502's all responses. uwsgi has a configuration
called "chain reloading" which allows for rolling restart of the uwsgi
processes, such that only one process at once in unavailable; see
uwsgi documentation ([1]).
The tradeoff is that this requires that the uwsgi processes load the
libraries after forking, rather than before ("lazy apps"); in theory
this can lead to larger memory footprints, since they are not shared.
In practice, as Django defers much of the loading, this is not as much
of an issue. In a very basic test of memory consumption (measured by
total memory - free - caches - buffers; 6 uwsgi workers), both
immediately after restarting Django, and after requesting `/` 60 times
with 6 concurrent requests:
| Non-lazy | Lazy app | Difference
------------------+------------+------------+-------------
Fresh | 2,827,216 | 2,870,480 | +43,264
After 60 requests | 3,332,284 | 3,409,608 | +77,324
..................|............|............|.............
Difference | +505,068 | +539,128 | +34,060
That is, "lazy app" loading increased the footprint pre-requests by
43MB, and after 60 requests grew the memory footprint by 539MB, as
opposed to non-lazy loading, which grew it by 505MB. Using wsgi "lazy
app" loading does increase the memory footprint, but not by a large
percentage.
The other effect is that processes may be served by either old or new
code during the restart window. This may cause transient failures
when new frontend code talks to old backend code.
Enable chain-reloading during graceful, puppetless restarts, but only
if enabled via a zulip.conf configuration flag.
Fixes#2559.
[1]: https://uwsgi-docs.readthedocs.io/en/latest/articles/TheArtOfGracefulReloading.html#chain-reloading-lazy-apps
Fix another tidy error caused by 1e4e6a09af23; as also noted in
f9a39b6703, these resources are necessary such that tidy does not
cleanup of smokescreen, and then force a recompilation of it again.
1e4e6a09af removed the resources for the unpacked directory, on the
argument that they were unnecessary. However, the directory (or file,
see below) that is unpacked must be managed, or it will be tidied on
the next puppet apply.
Add back the resource for `$dir`, but mark it `ensure => present`, to
support tarballs which only unpack to a single file (e.g. wal-g).
In the event that extracting doesn't produce the binary we expected it
to, all this will do is create an _empty_ file where we expect the
binary to be. This will likely muddle debugging.
Since the only reason the resourfce was made in the first place was to
make dependencies clear, switch to depending on the External_Dep
itself, when such a dependency is needed.
ab130ceb35 added a dependency on scripts.lib.zulip_tools; however,
check_postgresql_replication_lag is run on hosts which do not have a
zulip tree installed.
Inline the simple functions that were imported.
It should not use the configured zulip username, but should instead
pull from the login user (likely `nagios`), or an explicit alternate
provided PostgreSQL username. Failure to do so results in Nagios
failures because the `nagios` login does not have permissions to
authenticated the `zulip` PostgreSQL user.
This requires CI changes, as the install tests install as the `zulip`
login username, which allowed Nagios tests to pass previously; with
the custom database and username, however, they must be passed to
process_fts_updates explicitly when validating the install.
The Redis configuration, and the systemd file for it, assumes there
will be a pid file written to `/var/run/redis/redis.pid`, but
`/var/run/redis` is not created during installation.
Create `/run/redis`; as `/var/run` is a symlink to `/run` on systemd
systems, this is equivalent to `/var/run/redis`.
The systemd config file installed by the `memcached` package assumes
there will be a PID written to `/run/memcached/memcached.pid`. Since we
override `memcached.conf`, we have omitted the line that writes out the
PID to this file.
Systemd is smart enough to not _need_ the PID file to start up the
service correctly, but match the configuration. We create the
directory since the package does not do so. It is created as
`/run/memcached` and not `/var/run/memcached` because `/var/run` is a
symlink to `/run`.
The certbot package installs its own systemd timer (and cron job,
which disabled itself if systemd is enabled) which updates
certificates. This process races with the cron job which Zulip
installs -- the only difference being that Zulip respects the
`certbot.auto_renew` setting, and that it passes the deploy hook.
This means that occasionally nginx would not be reloaded, when the
systemd timer caught the expiration first.
Remove the custom cron job and `certbot-maybe-renew` script, and
reconfigure certbot to always reload nginx after deploying, using
certbot directory hooks.
Since `certbot.auto_renew` can't have an effect, remove the setting.
In turn, this removes the need for `--no-zulip-conf` to
`setup-certbot`. `--deploy-hook` is similarly removed, as running
deploy hooks to restart nginx is now the default; pass
`--no-directory-hooks` in standalone mode to not attempt to reload
nginx. The other property of `--deploy-hook`, of skipping symlinking
into place, is given its own flog.
PostgreSQL 11 and below used a configuration file names
`recovery.conf` to manage replicas and standbys; support for this was
removed in PostgreSQL 12[1], and the configuration parameters were
moved into the main `postgresql.conf`.
Add `zulip.conf` settings for the primary server hostname and
replication username, so that the complete `postgresql.conf`
configuration on PostgreSQL 14 can continue to be managed, even when
replication is enabled. For consistency, also begin writing out the
`recovery.conf` for PostgreSQL 11 and below.
In PostgreSQL 12 configuration and later, the `wal_level =
hot_standby` setting is removed, as `hot_standby` is equivalent to
`replica`, which is the default value[2]. Similarly, the
`hot_standby = on` setting is also the default[3].
Documentation is added for these features, and the commentary on the
"Export and Import" page referencing files under `puppet/zulip_ops/`
is removed, as those files no longer have any replication-specific
configuration.
[1]: https://www.postgresql.org/docs/current/recovery-config.html
[2]: https://www.postgresql.org/docs/12/runtime-config-wal.html#GUC-WAL-LEVEL
[3]: https://www.postgresql.org/docs/12/runtime-config-replication.html#GUC-HOT-STANDBY
These are both unsupported by PostgreSQL itself, as well as by Zulip;
the removal of Ubuntu Xenial and Debian Stretch support in Zulip 3.0
removed the requirement for PostgreSQL 9.6, and the previous versions
date back yet farther.
Writing the secret to the supervisor configuration file makes changes
to the secret requires a zulip-puppet-apply to take hold. The Docker
image is constructed to avoid having to run zulip-puppet-apply on
startup, and indeed cannot run zulip-puppet-apply after having
configured secrets, as it has replaced the zulip.conf file with a
symlink, for example. This means that camo gets the static secret
that was built into the image, and not the one regenerated on first
startup.
Read the camo secret at process startup time. Because this pattern is
likely common with "12-factor" applications which can read from
environment variables, write a generic tool to map secrets to
environment variables before exec'ing a binary, and use that for Camo.
The default in the previous commit, inherited from camo, was to bind
to 0.0.0.0:9292. In standalone deployments, camo is deployed on the
same host as the nginx reverse proxy, and as such there is no need to
open it up to other IPs.
Make `zulip::camo` take an optional parameter, which allows overriding
it in puppet, but skips a `zulip.conf` setting for it, since it is
unlikely to be adjust by most users.
The upstream of the `camo` repository[1] has been unmaintained for
several years, and is now archived by the owner. Additionally, it has
a number of limitations:
- It is installed as a sysinit service, which does not run under
Docker
- It does not prevent access to internal IPs, like 127.0.0.1
- It does not respect standard `HTTP_proxy` environment variables,
making it unable to use Smokescreen to prevent the prior flaw
- It occasionally just crashes, and thus must have a cron job to
restart it.
Swap camo out for the drop-in replacement go-camo[2], which has the
same external API, requiring not changes to Django code, but is more
maintained. Additionally, it resolves all of the above complaints.
go-camo is not configured to use Smokescreen as a proxy, because its
own private-IP filtering prevents using a proxy which lies within that
IP space. It is also unclear if the addition of Smokescreen would
provide any additional protection over the existing IP address
restrictions in go-camo.
go-camo has a subset of the security headers that our nginx reverse
proxy sets, and which camo set; provide the missing headers with `-H`
to ensure that go-camo, if exposed from behind some other non-nginx
load-balancer, still provides the necessary security headers.
Fixes#18351 by moving to supervisor.
Fixeszulip/docker-zulip#298 also by moving to supervisor.
[1] https://github.com/atmos/camo
[2] https://github.com/cactus/go-camo
This is an additional security hardening step, to make Zulip default
to preventing SSRF attacks. The overhead of running Smokescreen is
minimal, and there is no reason to force deployments to take
additional steps in order to secure themselves against SSRF attacks.
Deployments which already have a different external proxy configured
will not gain a local Smokescreen installation, and running without
Smokescreen is supported by explicitly unsetting the `host` or `port`
values in `/etc/zulip/zulip.conf`.
In a subsequent commit, we intend to include it from
`zulip::app_frontend_base`, which is a layering violation if it only
exists in the form of a profile.
This will cause the output binary path to be sensitive to golang
version, causing it to be rebuilt on new golang, and an updated
supervisor config file written out, and thus supervisor also
restarted.
As with the previous commit for `/srv/golang`, we have the custom of
namespacing things under `/srv` with `zulip-` to help ensure that we
play nice with anything else that happens to be on the host.
We have the custom of namespacing things under `/srv` with `zulip-`
to help ensure that we play nice with anything else that happens
to be on the host.
