| 4 Jul 2025 |
 Theuni | Arian: yeah, i could upgrade the wants/after to requires, so a failed order unit won't trigger a subsequent renewal failure | 06:17:16 |
| Theuni | (or well maybe it does, not sure but then it would fail due to a dependency and not an internal failure) | 06:17:38 |
| Theuni | ah but then the "inversion of control" pattern makes it ugly again. | 06:18:45 |
| Theuni | Reminder to self: overall i'm trying to get complexity and the relationships and maybe even the number of units down. | 06:31:00 |
| Theuni | One aspect: we basically need one assurance and one signal to interact with certificate consumer units (nginx, postfix, ...): | 06:31:33 |
| Theuni |
- the assurance: the files referenced in your config file are now available and are valid ssl certificates. Go forth and start!
| 06:31:58 |
| Theuni |
- the signal: the content of the files has changed and you likely want to reload/restart to pick up the new content.
| 06:32:22 |
| Theuni | The assurance doesn't really even have to be a valid/current/... acme certificate, but basically something that allows the service to start (e.g. the self signed certificates or maybe even an outdated acme cert). | 06:32:53 |
| Theuni | Which is already used for things like allowing bootstrapping the infrastructure to answer HTTP-01. | 06:33:46 |
| Theuni | Now, we do need some unit that stays active (we used the -finished targets for this previously) so that s-t-c can trigger config updates. This was very indirect previously - moving this to a unit that is oneshot/remainafterexit (the "order" unit in my patch) makes config changes trigger more precisely. | 06:35:11 |
| Theuni | However, active units can't be triggered by timers, hence a "renew" unit that can be triggered by a timer. Initially I started out with the renew unit just being a "systemctl restart acme-${cert}", having all the tasks in a single bash script. I was somewhat wary of duplicating too much (bash) code (i did duplicate the nix code for the units) so I chose an inversion of control pattern where the renew unit then triggers the order unit again to make sure permission settings, relocating the updated certificates etc. happens in only a single place as well as triggering the reloads for consumers. | 06:37:21 |
| Theuni | (I'm using the chat to talk out my thought processes. Basically just🎈🦆ing here ...) | 06:39:22 |
| Theuni | *
- the assurance: the files referenced in your config file are now available and are (syntactically) valid ssl certificates. Go forth and start!
| 06:39:57 |
| Theuni | That inversion makes the dependencies muddied again. I could split it up in more units, moving the post-processing code in a separate unit, or just use a shared (execstartpost) script (or partial). | 06:42:16 |
| Theuni | Hmm. Consolidating multiple certificates renewing at the same time isn't much of an issue I guess as we distribute the renewal timers over time anyway. | 06:43:05 |
| Theuni | * Hmm. Consolidating client reload signals for multiple certificates renewing at the same time isn't much of an issue I guess as we distribute the renewal timers over time anyway. | 06:43:18 |
| Theuni | So. I guess two units would suffice: 1st unit (acme-${cert}) is what clients depend via want/after on, which guarantees a syntactically valid certificate is there - which updates the certificate parameters when the config changes. Interestingly, the last part isn't really needed for the assurance itself. 2nd unit to issue ACME renewals. | 06:46:40 |
| Theuni | I wonder whether the "update the parameters" (which requires an active unit to trigger selectively) could/should move elsewhere. It can't be merged with the 2nd unit because that conflicts with the timer requirement. | 06:47:22 |
| Theuni | The renewal itself does depend on the order being current/successful, though as hexa noted. | 06:48:05 |
| Theuni | 
Download Screenshot 2025-07-04 at 10.12.07.png | 08:12:46 |
| Theuni | Alright. Some discussion with leona and max lead to this ^^ | 08:12:49 |
| Theuni | I'll put that into code and see how that works. | 08:13:00 |
| Theuni | something that doesn't fit in there is that preliminary self signed certificates can be turned off currently. | 08:22:52 |
| Theuni | this setup would always introduce (temporary) self-signed certificates. (currently if you turn off preliminary self signed certificates and lets encrypt doesn't work for some reason, we don't start the consumer service at all because the configs will be invalid) | 08:23:50 |
| Theuni | i would consider it an acceptable shift in detail wrt to reduced overall complexity. | 08:24:40 |
| Theuni | * i would consider it an acceptable tradeoff with the benefit of reduced complexity. | 08:25:11 |
| Theuni | otoh if someone runs dns-01 everywhere and doesn't ever need to show self signed certificates and wants to reduce the risk of exposing users to those ... | 08:26:12 |
| Theuni | hmpf. | 08:26:15 |
| Theuni | however, if you have a more complex service that acts as a "nexus" then maybe only one of multiple vhosts uses dns-01, others might be using http-01 or tls-01 and need the self-signed certificates anyway and then you get unpredictable behaviour. | 08:29:06 |
| Theuni | in that sense, the tradeoff seems even more beneficial: reduced complexity and more predictable behaviour. | 08:29:26 |
