Changes to point the systemd services file to /etc/default/caddy

[hvisage]

This is a "simple" method to not mess with the systemd services file but to allow the sysadmin to use the /etc/default/caddy to point to a different (especially .json) config file and EXTRA_PARAMS support for --resume (or --watch etc.)

I know there is a "new recommended" method to make use of systemctl edit as mentioned here but that is not what I'm "ised" to, and the /etc/default/caddy is easier to ansible lineinfile edit

[francislavoie]

I don't think that's a good idea. --resume doesn't really make sense to be paired with a Caddyfile; you'll get unexpected behaviour because the autosaved config will take precedence over any changes made to your file specified in --config. This was a well-debated topic.

I realize you're making this opt-in, but I think this muddies the water. I'd rather people use systemctl edit instead if they need to deviate from either service file.

[hvisage]

1. --resume okay, what about I remove references for that? (EXTRA_PARAMS can still be used without it for other options)

2. how do you automate/script systemctl edit from Ansible/etc. ? It only opens a blank file, meant for Environment variables from the tests I've done on systemctl edit caddy & systemctl edit caddy.service on the Debian where I did installed via the packages

The issue here: I want to point to a different --configfile (Specifically json that was autogenerated from elsewhere), several services use /etc/default/<service_name> to have it dynamically point to other config files without messing with the services/unit files. Files like /etc/default/caddy is typically marked as "volatile/user-edited" where as /lib/systemd/system/caddy.service is typically frowned upon to edit as the package managers should warn when those changed with out updates to the packages databases

[francislavoie]

See https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units#editing-unit-files for an explanation of how it works. You don't need to use edit if you're automating, you just drop the file in the right place as described there.

[carlwgeorge]

I agree with @francislavoie, systemd has a robust and easy to use override system with multiple options for customizing unit files. There isn't a compelling reason to do something non-standard here. I'm -1 on this pull request.

As far as ansible goes, I think it's much easier to write a new drop-in file with the copy module than it is to modify an existing file with the lineinfile module. Anytime I can avoid writing regex I will. Here's an example.

- name: override caddy unit file
  copy:
    dest: /etc/systemd/system/caddy.service.d/custom.conf
    contents: |
      [Service]
      ExecStart=
      ExecStart=/usr/bin/caddy run --environ --config /opt/Caddyfile
      ExecReload=
      ExecReload=/usr/bin/caddy reload --config /opt/Caddyfile

The empty directives aren't a typo, they are necessary when overriding because a unit file can have multiple of those directives, so you have to "clear" the directive from the stock file.