What does`processes` do in fly.toml? Where's the full config documentation?

If you let flyctl create a fly.toml or you look at the GitHub examples (org:fly-apps language:toml processes) you will find a processes directive.

But I could not find anything in the documentation explaining what the processes does.

From the examples you can see that it is always an empty list when on the top level and ["app"] when inside [[services]].

What does it do? Where is the full documentation for the fly.toml?
For example, there are experimental flags such as auto_rollback that are not in the fly.io/docs.

Thank you in advance.

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It’s for setting up multi-process apps like described here - Preview: multi process apps (get your workers here!)

On auto_rollback… it’s something they’re still working on I reckon.
This could also be the thing that makes a deploy re-try with the previous version, if your current deploy is failing for whatever reason.

@FrequentFlyer thak you.

Interesting as it completely goes against what is described in the doc: Running Multiple Processes Inside A Fly.io App, where they recommend using a process manager.

Yes the auto_roolback and others I would find from the community forum. But I would expect an official documentation.

That page is more like a survey of what was available before this feature was build or while this feature was being built.

Perhaps Fly will benefit from adding an PR approver docbot, which would get in the way of each PR, and ask for an equivalent doco update.

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We’ll be doing a big docs update soon. We’ll include adding this behavior.

The reason this feature wasn’t added so far: it’s still technically a preview feature with known bugs and quirks. That said, we want people to use it so we can improve on it with better understanding of what people need.