NixOS VM tests: Difference between revisions
imported>Teto m adding some issues I met while working on multihoming issues: |
imported>Asdf8dfafjk m link to keys |
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1. By default the qemu-vm setups a `user` based nic: virtualisation.qemu.networkingOptions. You need to override the option to get rid of this interface. | 1. By default the qemu-vm setups a `user` based nic: virtualisation.qemu.networkingOptions. You need to override the option to get rid of this interface. | ||
2. As of this writing nixpkgs will generate interfaces starting from `eth1` (instead of `eth0`). | 2. As of this writing nixpkgs will generate interfaces starting from `eth1` (instead of `eth0`). | ||
Keys: https://en.wikibooks.org/wiki/QEMU/Monitor#sendkey_keys | |||
Revision as of 18:03, 10 August 2020
The test infrastructure entry point is nixos/lib/testing.nix. The test infra relies on the qemu build-vm code to generate virtual machines.
It will generate a test driver (a wrapper of nixos/lib/test-driver/test-driver.pl) in charge of creating the network. It will start one vde-switch and its associated socket per vlan (defined in virtualisation.vlans). IPs are assigned declaratively according to the number of vlan via the function `assignIPAddresses`.
The driver (of the form /nix/store/668bqxvsv6rn9hy8n4nmaps9ma2i5k4r-nixos-test-driver-<TESTNAME>) will launch the different vms passed as arguments. The wrapper `bin/nixos-run-vms` is in charge to start the driver with the correct VM script as arguments.
Once the driver is loaded, depending on the environment variables `tests` it will run in an interactive mode or run some perl code (`testScript`). In interactive mode, you can run `startAll` followed by `joinAll` to start and keep the VM alive
How to debug tests ?
You can run the tests interactively as described in nixos manual. When you run `nix-build ./nixos/tests/login.nix`, the resulting output gives you a summary of the results, but to gain access to the VM, you can run `nix repl ./nixos/tests/login.nix` and see the ran VM via `driver.outPath`.
I don't see any prompt ? (qemu window pitch black)
Check the output for `malformed JSON string, neither array, object, number, string or atom, at character offset 0 (before "\x{0}\x{0}\x{0}\x{0}...") at /nix/store/1hkp2n6hz3ybf2rvkjkwrzgbjkrrakzl-update-users-groups.pl line 11`. You should purge the state present in rm -rf /tmp/vm-state-<VM_NAME>
= Setting `virtualisation.vlans` does not create the expected interfaces
There are two sides to the problem: 1. By default the qemu-vm setups a `user` based nic: virtualisation.qemu.networkingOptions. You need to override the option to get rid of this interface. 2. As of this writing nixpkgs will generate interfaces starting from `eth1` (instead of `eth0`).
Keys: https://en.wikibooks.org/wiki/QEMU/Monitor#sendkey_keys