Change etc/hosts using shell.nix

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Is it possible to use lorri + shell.nix to modify /etc/hosts for a particular project on my machine?

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Apparently using HOSTALIASES HOSTALIASES

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Is it just me or does it not work in NixOS?

$ nixos-version
21.03pre244932.84d74ae9c9c (Okapi)
$ echo 'n nixos.org' >> ~/.hosts
$ export HOSTALIASES=~/.hosts
$ curl -v n
* Could not resolve host: n
* Closing connection 0
curl: (6) Could not resolve host: n

Edit: added NixOS version.

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Yea you are correct. It does not seem to work on my end as well. :frowning:

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@blaggacao has an interest in this topic

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/etc is usually owned by root, which would mean you need to execute nix-shell as root. Which seems way outside of it’s normal bounds of responsibility.

Another option might be buildFHSUserEnv, but I’ve never used it with nix-shell.

I would try to see if there’s any user-level options that are available.

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Found this:

It emulates per-user hosts using LD_PRELOAD. Just tested and it works fine for me.

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for many reasons, I’m kinda of glad it doesn’t work.

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:smiley: Indeed! I think you raised a valid point.

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@j-k oh thanks! Indeed, I just prototyped this, fingers are still hot:

https://github.com/numtide/devshell/pull/28

If someody has interest in promoting it’s inclusion, I (and certainly @zimbatm, too) would appreciate if you could expose your use case in the corresponding issue.

There is an ester egg on the related issue akin to figiel/hosts :wink:

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I use buildFHSUserEnv with nix-shell all the time. It works fine (though I’d like more control over how much of /etc it carries over to ‘inside’ the userenv - right now it only selects the essentials, and I lose e.g. my zsh configuration).

I don’t see an obvious way to overwrite /etc/hosts in there, though.

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@amanjeev You can now try out my branch, I just fixed the obvious things and it works now.

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Thank you @blaggacao. I have been busy lately. Will try and let you know. Although I do not use devshell

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mkDevShell is intended to be an improved successor of mkShell by the same author.