rebuilding while offline

[schmittlauch]

When using the default configuration where programs.home-manager.path points to a remote URL it is not possible to rebuild one's home configuration with home-manager switch when not connected to the internet.
I deliberately configured my system config to be rebuildable even when offline, so I ask for either an option to disable updating remote paths or for an autodetection of being offline/ unable to pull in the paths. (GitHub could be down, too)

This is especially important because even adding a line to one's vimrc using home-manager requires a rebuild and should not depend on internet connectivity.

[rycee]

Thanks for the report. Yeah, for this case I would suggest cloning the Home Manager repository and changing programs.home-manager.path to point to the absolute path of your clone. Something like

programs.home-manager.path = "$HOME/devel/home-manager";

Then update Home Manager using git pull.

The lack of control over remote imports is up to the Nix tools and cannot be controlled by Home Manager.

[schmittlauch]

As a compromise it'd be nice to manage the home-manager sources via nix-channels as well. Updating the local git repo is an additional effort, but I update the nix-channels anyways.
Is that possible?

[rycee]

In principle it should straight forward to distribute Home Manager through a channel. But it would require setting up build infrastructure and hosting for the channel directory. Perhaps nixos.org would be willing to lend their hydra and CDN for the purpose?

In any case, I'm unlikely to start looking into this anytime soon due to work and other priorities but would be willing to assist anybody wanting to look into it.

[dtzWill]

On Tue, 23 Oct 2018 13:40:52 -0700, Robert Helgesson ***@***.***> wrote: In principle it should straight forward to distribute Home Manager through a channel. But it would require setting up build infrastructure and hosting for the channel directory. Perhaps nixos.org would be willing to lend their hydra and CDN for the purpose? In any case, I'm unlikely to start looking into this anytime soon due to work and other priorities but would be willing to assist anybody wanting to look into it.

I think one of us needs to teach 'nix-channel' how to use a git repo directly, it's a very common use case and AFAIK is the form in which virtually all channels are created from anyway. Or maybe just a bit of tooling to bridge the gap, dunno. I know you can point it at the tarballs but that's a smidge inefficient (full dl for every commit, also gz vs xz, etc.) but I want to say that it also breaks something but I don't remember what-- only that I thought it was great until I ran into this problem and now just have a bunch of local git clones instead since apparently that's "better" :(. Oh-- I'm not sure this is the only limitation, but one problem is that nixpkgs acquired this way won't know what revision it is which is annoying if not problematic.

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[Mic92]

You could do the following to use the nix-channel command:

$ nix-channel --add https://github.com/rycee/home-manager/archive/master.tar.gz home-manager
$ nix-channel --update
$ ls -la .nix-defexpr/channels/home-manager

programs.home-manager.path = "$HOME/.nix-defexpr/channels/home-manager";

At the moment home-manager is only 713K big so downloading everything is probably faster then a git pull. Some nodejs packages itself require the same size to describe its dependencies: NixOS/nixpkgs#49082 (comment)

@rycee do you think this should go to the documentation?

[rycee]

@Mic92 That's nice! My understanding of the channel format was that it needed some special setup with a binary-cache-url file. If this works then I definitely would like to add it to the documentation. I will try it out as soon as possible. Thanks a lot!

[Mic92]

No the binary cache is orthogonal to the channel, which is literally just a tarball with a default.nix.

[rycee]

@Mic92 Created #475 to switch the installation instructions to recommend nix-channel instead. No need to set programs.home-manager.path if using home-manager as the channel name.

I've actually intended to support nix-channel for a long time but never got around to it because I assumed it would need some work on the CI side to create a correctly formatted directory: https://nixos.org/nix/manual/#channel-format

[rycee]

I merged #475 so I'll close this ticket. From now on the recommended way to set up Home Manager is using nix-channel and this will allow the Home Manager expression to be reliably available even while offline.