[debops-users] common playbook and disable ferm

Maciej Delmanowski drybjed at drybjed.net
Sat Nov 4 01:21:38 CET 2017

On Nov 04, Jan Kowalsky wrote:
> Hi all,

Hello, and welcome to the mailing list as well as to the DebOps project!

> In documentation and older mailing list posts I found the following
> configuration possibilities:
> ferm: False
> ferm__enabled: False
> The ferm: False doesn't work for me at all. The ferm_enabled: False
> still installs ferm and generates rules but doesn't activate them.

The old '<role>: False' variable style was used long ago to enable/disable
roles in the common playbook without the need to modify it. However I found
issues with Ansible interpreting the 'ferm' variable name during package
installation so I changed the style of the variables to '<role>__enabled' to
avoid collisions.

> So my question: is there any possibility to use the common (and other)
> playbook without ferm and disable it completely?

In the early days, some of the DebOps roles like 'debops.postfix' generated
ferm configuration files directly in the '/etc/ferm/ferm.d/' directory when
more involved rules were required. Since I didn't want to have to create that
directory in each role separately, as well as include separate handlers to
restart ferm, the 'debops.ferm' role became sort of a required dependency
and directory creation was done even when the firewall itself was disabled so
that other roles wouldn't break when the directory was missing.

Over time I updated the 'debops.ferm' role to support more advanced
configurations via role dependent variables and management of the firewall
rules directly by other roles became unnecessary. This means that it should be
now possible to update the 'debops.ferm' role so that disabling it skips all
relevant tasks, the 'ferm' package is not installed, directories are not
created, etc. This hopefully can open up the possibility of making the
'debops.ferm' role a non-essential role, so that it could be replaced by say,
'debops.nftables' role when it's created.

However keep in mind that DebOps is focused on a production environment, where
having a proper firewall on a host is essential, especially with IPv6 where
most of the IP addresses are publicly reachable even when IPv4 NAT is used.
This makes a firewall choice a tricky subject, since you would want to add
support for multiple firewalls at once to each role that requires it (for
example 'debops.nginx', 'debops.mariadb_server', etc.) and pick the active one
to configure service access. There is precedence for that with roles like
'debops.gitlab' supporting different database engines which are picked out
either automatically or by the user during deployment, so that's definitely
possible in the future.

Right now, when 'debops.ferm' role is disabled, even when the 'ferm' package
is installed, it should be completely disabled and shouldn't affect the host's
firewall. I think that it should be possible to easily use 'firehol' alongside
DebOps. Since other roles defer to 'debops.ferm' role to manage the firewall,
they shouldn't change its state as well.

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