Add background jobs

[enricostano]

WAT

We need a background jobs system in order to send emails, mobile push notifications, etc.

Dependencies

coopdevs/timeoverflow-provisioning#47 (Install Redis)

TODO BEFORE DEPLOY

• provision redis on staging (Ansible scripts)
• install redis by hand in production 😬

[markets]

Nice @enricostano! Taking into account that we'll have (and we'll depend on) redis, we can maybe drop the memcached dependency and use redis also as a cache store, in the future, so this will simplify our infrastructure.

[sauloperez]

that's a good idea @markets . I wonder though if we can completely get rid of the cache store to simplify the infrastructure as well as the code even further.

[markets]

Yes, right now we're using caching (=> and memcached) only for this #327 I think :(

[sauloperez]

Yep, that's why we got it in our radar. 🔪 if possible.

[enricostano]

we can maybe drop the memcached dependency and use redis also as a cache store, in the future, so this will simplify our infrastructure.

I whish we could, I remember a conversation with sys admins about redis not being the best option for cache... but I need to dig into that again. It was probably related to performance, I'll look into it.

[sauloperez]

Could be. But keep in mind that our use case is rather small. It might be one of those cases where the tradeoff of using it as a cache store makes sense.

[markets]

ok @enricostano not really sure (from a perfomance perspective) if redis can compete with memcached at scale. Probably no, since memcached was designed for this purpose. But as @sauloperez said, it's a question of trade-offs, and in our current situation: caching only is used to cache the devise reset passwords, resources are limited (infra, team)... maybe it wouldn't be a bad bad idea.

But to be honest, I'd try to revisit #327, think alternatives (remove, reimplement with DB), and probably just 🔥 the cache store for now, as Pau also pointed out:

🔪 if possible