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How could I allow users to schedule sending emails at a specific interval? (self.golang)
submitted 1 week ago by lena to c/golang@programming.dev
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Cross-posted from "How could I allow users to schedule sending emails at a specific interval?" by @lena@gregtech.eu in !learn_programming@programming.dev

Basically, I'm trying to figure out how I could allow a user to send a schedule in the cron syntax to some API, store it into the database and then send an email to them at that interval. The code is at gragorther/epigo. I'd use go-mail to send the mails.

I found stuff like River or Asynq to schedule tasks, but that is quite complex and I have absolutely no idea what the best way to implement it would be, so help with that is appreciated <3

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[–] okwhateverdude@lemmy.world 4 points 1 week ago (1 children)

Are your users technical? If not, crontab syntax is definitely to be avoided. Instead, I'd offer some simple options like daily, weekly, monthly, etc. Then convert that syntax into crontab syntax.

I glanced at the repo, but there is no content in the README.md to get a sense of what your project is actually doing.

For processing cron, you should consider just using cron. You can setup a user specific to the process, use that user's crontab, and manage the entries. If the source of truth will be from the database, then you don't even need to read the crontab itself, only (over)write it on demand.

[–] lena 1 points 1 week ago (1 children)

I was thinking I could offer the option to use cron, if not they can just select an option from a dropdown.

regarding my nonexistent readme, this is basically a digital dead man switch. The user sets an interval to send emails with a link to them , and if they don't click on the link for a few months, they get marked as dead and messages they specified beforehand get sent out to groups of users.

[–] okwhateverdude@lemmy.world 2 points 1 week ago (1 children)

I'd carefully consider using email for this. If you're hosting the service, you might need to use one of the bigger email providers that already have reputation (unless you already have good IPs with good rep). Otherwise, you risk the emails sitting in spam and people's switches being flipped. If it is self-hosted, you'll probably need to explain the risks to users.

Given today's world of pocket computers, you might consider using push notifications of some kind. Or have a companion client that pokes an API and there is some kind of challenge/response.

[–] lena 2 points 1 week ago (1 children)

Yeah, I'll use one of the major email providers, I am aware of the risks of self-hosting email. And yes, I will implement some kind of push notification system, either through the browser or via a mobile app.

[–] okwhateverdude@lemmy.world 2 points 1 week ago

Okay cool, just making sure you covered all your bases 🖖

[–] Feyd@programming.dev 2 points 1 week ago (2 children)

This has worked well for me before, on a small scale https://github.com/robfig/cron

[–] Feyd@programming.dev 2 points 1 week ago

Note that while it is simple, you have to handle schedule persistence yourself, unlike the 2 you linked since they are backed by pg or redis

[–] lena 2 points 1 week ago (1 children)

correct me if I'm wrong, but it seems like this wouldn't scale well

[–] Feyd@programming.dev 2 points 1 week ago (1 children)

In what way? You haven't provided any information about scaling requirements

[–] lena 1 points 1 week ago (1 children)

I would have to store the users' cron jobs in a database, and then run some kind of loop on startup to start the cron jobs.

[–] Feyd@programming.dev 1 points 1 week ago (1 children)

That is accurate, though it doesn't say anything about scaling requirements

[–] lena 1 points 1 week ago (1 children)

Oops, missed that part. Ideally, this would be able to handle thousands of users

[–] Feyd@programming.dev 1 points 1 week ago

Thousands is nothing, so having a single service holding the info on memory shouldn't be a problem

[–] JustJack23@slrpnk.net 2 points 1 week ago* (last edited 1 week ago)

Depending of how complicated you want it to be of course.

I would implement it by using the basic goroutines, a wait group to keep track of the goroutines and sleep for the recurring duration.

Maybe a more optimal solution would be to use a workerpool.

Also what amount of emails are we talking about and what kind of recurring duration(1/hour or 1/year)