[ggrochow]

As someone who's been using flynn in production for a month or two, some things to be aware of. (Devops is not one of my strongpoints, so keep that in mind)

You want to use an external blob-store, by default it uses its own postgres to store them. However, it also doesn't do any garbage collection, so we ran out of HD space on our cluster, causing postgres to go into read-only mode. This prevented us from pushing updates / changing any app-config settings ( ENV, Scaling, etc ). Thankfully we were hosting our own DB off-cluster or that too would have been read only.

The default limits on memory is 1gb, and for our app, when it runs out, it just crashes. Leaving no obvious error messages to be found.

Obviously RTFM as well, (especially this part https://flynn.io/docs/production) we had some other issues that could have easily been prevented.

Huge shout-out to the team that hangs out in their IRC channel, they were a massive help in solving the problems we've came across.

Using it when it works is lovely, we switched off of heroku recently and its been a very similar experience.

[Titanous]

> You want to use an external blob-store, by default it uses its own postgres to store them. However, it also doesn't do any garbage collection

The lack of garbage collection by default will be fixed in next week's stable release, we're really sorry that it caused you pain!

> The default limits on memory is 1gb, and for our app, when it runs out, it just crashes. Leaving no obvious error messages to be found.

Indeed, we're working on documenting this and exposing out-of-memory events in the app logs so that this is obvious.

[twic]

Good luck with the out-of-memory handling. From personal experience, that's easier said than done.

[Titanous]

Here's the issue tracking this: https://github.com/flynn/flynn/issues/3375

[koolba]

> You want to use an external blob-store, by default it uses its own postgres to store them. However, it also doesn't do any garbage collection, so we ran out of HD space on our cluster, causing postgres to go into read-only mode. This prevented us from pushing updates / changing any app-config settings ( ENV, Scaling, etc ). Thankfully we were hosting our own DB off-cluster or that too would have been read only.

By garbage collection are you referring to the binary blobs for built slugs?

[Titanous]

Correct. By default app slugs are stored as large objects in the built-in Postgres cluster, to allow deployment without external dependencies. For production we recommend moving to AWS S3, Google Cloud Storage, or Azure Storage.

Garbage collection of old slugs is supported though it isn't on by default (it will be in the next stable release).