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
These checks suffer from a couple notable problems:
- They are only enabled on staging hosts -- where they should never
be run. Since ef6d0ec5ca, these supervisor processes are only
run on one host, and never on the staging host.
- They run as the `nagios` user, which does not have appropriate
permissions, and thus the checks always fail. Specifically,
`nagios` does not have permissions to run `supervisorctl`, since
the socket is owned by the `zulip` user, and mode 0700; and the
`nagios` user does not have permission to access Zulip secrets to
run `./manage.py print_email_delivery_backlog`.
Rather than rewrite these checks to run on a cron as zulip, and check
those file contents as the nagios user, drop these checks -- they can
be rewritten at a later point, or replaced with Prometheus alerting,
and currently serve only to cause always-failing Nagios checks, which
normalizes alert failures.
Leave the files installed if they currently exist, rather than
cluttering puppet with `ensure => absent`; they do no harm if they are
left installed.
Host-based md5 auth for 127.0.0.1 must be removed from `pg_hba.conf`,
otherwise password authentication is preferred over certificate-based
authentication for localhost.
This requires switching to a reverse tunnel for the auth connection,
with the side effect that the `zulip_ops::teleport::node` manifest can
be applied on servers anywhere in the Internet; they do not need to
have any publicly-available open ports.
This means that services will only open their ports if they are
actually run, without having to clutter rules.v4 with a log of `if`
statements.
This does not go as far as using `puppetlabs/firewall`[1] because that
would represent an additional DSL to learn; raw IPtables sections can
easily be inserted into the generated iptables file via
`concat::fragment` (either inline, or as a separate file), but config
can be centralized next to the appropriate service.
[1] https://forge.puppet.com/modules/puppetlabs/firewall
These thresholds are in relationship to the
`autovacuum_freeze_max_age`, *not* the XID wraparound, which happens
at 2^31-1. As such, it is *perfectly normal* that they hit 100%, and
then autovacuum kicks in and brings it back down. The unusual
condition is that PostgreSQL pushes past the point where an autovacuum
would be triggered -- therein lies the XID wraparound danger.
With the `autovacuum_freeze_max_age` set to 2000000000 in
`postgresql.conf`, XID wraparound happens at 107.3%. Set the warning
and error thresholds to below this, but above 100% so this does not
trigger constantly.
Matching the full process name (-x without -f) or full command
line (-xf) is less prone to mistakes like matching a random substring
of some other command line or pgrep matching itself.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
This verifies that the proxy is working by accessing a
highly-available website through it. Since failure of this equates to
failures of Sentry notifications and Android mobile push
notifications, this is a paging service.
In production, the `wildcard-zulipchat.com.combined-chain.crt` file is
just a symlink to the snakeoil certificates; but we do not puppet that
symlink, which makes new hosts fail to start cleanly. Instead, point
explicitly to the snakeoil certificate, and explain why.
Alex Vandiver
Anders Kaseorg
Tim Abbott