support rspamd when configured

[eleith]

this PR adds rspamd as an optional service

RSPAMD_ENABLE can be set to enable the service
RSPAMD_WEB_PASSWORD can be be set to require a password when logging into the rspamd web dashboard

all configurations were taken from: https://anonaddy.com/self-hosting/

this resolves #93

[crazy-max]

Thanks for this PR! See my comments and let me know what you think.

[eleith]

i've reworked this PR to install and configure rspamd internally in the container

locally, i can confirm rspamd can be enabled/disabled and the web dashboard requires a password

[crazy-max]

@eleith Looks great thanks! In a follow-up I will update our test workflow and add a matrix to test against rspamd and opendkim/dmarc so we can check if services are up as expected.

[crazy-max]

Btw do we need to update the Generate DKIM private/public keypair section in the README relative to Rspamd or is it ok to use opendkim-genkey for it?

[eleith]

Btw do we need to update the Generate DKIM private/public keypair section in the README relative to Rspamd or is it ok to use opendkim-genkey for it?

i was gonna leave it alone in an attempt to keep this PR from growing. but, with that said, this change isn't required (opendkim generated keys still would work) but it would be more aligned with the anonaddy's recommendation to do the following:

sudo rspamadm dkim_keygen -s 'default' -b 2048 -d example.com -k /var/lib/rspamd/dkim/example.com.default.key | sudo tee -a /var/lib/rspamd/dkim/example.com.default.pub

[crazy-max]

Btw do we need to update the Generate DKIM private/public keypair section in the README relative to Rspamd or is it ok to use opendkim-genkey for it?

i was gonna leave it alone in an attempt to keep this PR from growing. but, with that said, this change isn't required (opendkim generated keys still would work) but it would be more aligned with the anonaddy's recommendation to do the following:

sudo rspamadm dkim_keygen -s 'default' -b 2048 -d example.com -k /var/lib/rspamd/dkim/example.com.default.key | sudo tee -a /var/lib/rspamd/dkim/example.com.default.pub

Sure let's do that in a follow-up

[crazy-max]

LGTM thanks gain!