NixOS VM tests: Difference between revisions
imported>Asdf8dfafjk m link to keys |
imported>Teto updated it to reflect some python changes |
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The test infra relies on the qemu build-vm code to generate virtual machines. | 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. | It will generate a test driver (a wrapper of nixos/lib/test-driver/test-driver.py) in charge of creating the network. | ||
It will start one vde-switch and its associated socket per vlan (defined in virtualisation.vlans). | 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`. | IPs are assigned declaratively according to the number of vlan via the function `assignIPAddresses`. | ||
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Once the driver is loaded, depending on the environment variables `tests` it will run in an interactive mode or run some perl code (`testScript`). | 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 ` | In interactive mode, you can run `start_all` followed by `join_all` to start and keep the VM alive | ||
== How to debug tests ? == | == How to debug tests ? == | ||
You can run the tests interactively as described in nixos manual. | You can run the tests interactively as described in [https://nixos.org/manual/nixos/stable/index.html#sec-running-nixos-tests-interactively]. | ||
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 | 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`. | |||
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You should purge the state present in rm -rf /tmp/vm-state-<VM_NAME> | 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: | 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. | 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. | ||
Revision as of 22:21, 6 February 2021
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.py) 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 `start_all` followed by `join_all` to start and keep the VM alive
How to debug tests ?
You can run the tests interactively as described in [1]. 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