Cheatsheet: Difference between revisions

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=== Building a service as a VM (for testing) ===

While `nixos-rebuild build-vm` allows to build a vm out of the current system configuration, there is a more light-weight alternative when only a single service needs to be tested.

While <code>nixos-rebuild build-vm</code> allows to build a vm out of the current system configuration, there is a more light-weight alternative when only a single service needs to be tested.

Given the following configuration:

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a vm can be build using the following command:

$ nixos-rebuild -I nixpkgs=/path/to/nixpkgs -I nixos-config=./vm.nix build-vm

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where `-I nixpkgs=/path/to/nixpkgs` is optionally depending whether the vm should be build from git checkout or a channel.

where <code>-I nixpkgs=/path/to/nixpkgs</code> is optionally depending whether the vm should be build from git checkout or a channel.

On non-nixos (linux) systems the following command can be used instead:

nix-build '<nixpkgs/nixos>' -A vm -k -I nixos-config=./vm.nix

$ nix-build '<nixpkgs/nixos>' -A vm -k -I nixos-config=./vm.nix

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By default the resulting vm will require X11 to create a virtual display.

By specifying additional arguments via the environment variables <code>QEMU_OPTS</code>and <code>QEMU_KERNEL_PARAMS</code> it is possible to reuse the current running terminal as serial output of the vm:

$ export QEMU_OPTS="-nographic -serial mon:stdio" QEMU_KERNEL_PARAMS=console=ttyS0

$ /nix/store/lshw31yfbb6izs2s594jd89ma4wf8zw6-nixos-vm/bin/run-nixos-vm

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Add the following `default.nix` to the project:

Add the following <code>default.nix</code> to the project: