Automatically upgrading to nixOS 21.03pre despite using nixOS 20.09 channel

[Church-]

So the issue is as I understand,

1. system.stateVersion on each host is set to 20.09 in their config expressions.

2. My channels on my local device from which I deploy from are set to either:

• nixpkgs-unstable
• nixos-20.09 and nixpkgs-unstable

3. It seems to upgrade my hosts to be deployed to from 20.09 to 21.03pre which is breaking some of my installs/services.

After talking to @adisbladis on irc he deemed this to be a bug, I should note that this doesn't seem to be happening to all my hosts. Only two out of three.

[adisbladis]

After talking to @adisbladis on irc he deemed this to be a bug

At the very least it warrant some investigation and/or tests and docs.
I'm not entirely sure this is a bug, but we may want to manage expectations around channels/stateVersion and how NixOps deals with these.

[NobbZ]

21.03pre is from nix{o,pkg}s-unstable.

[Church-]

@NobbZ Indeed it is.

After attempting to pin nixpkgs to the 20.09 tagged commit again I was finally able to deploy the correct version.

I think I agree with @adisbladis that we might just need more documentation around this issue.