chore(tvix/tests): rename to //tvix/boot r/6652

This is mostly boot tooling, the integration test is just one instance
making use of it.

Expose initrd, kernel and runVM as a separate target to CI, and move the
tests to a subdirectory.

Change-Id: I1d22cd68bf5af095bc11dd9d7117b62956c7f7f2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9465
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 136 insertions, 0 deletions

diff --git a/tvix/boot/README.md b/tvix/boot/README.md
new file mode 100644
index 000000000000..79fca31ebc71
--- /dev/null
+++ b/tvix/boot/README.md
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+# tvix/boot
+
+This directory provides tooling to boot VMs with /nix/store provided by
+virtiofs.
+
+In the `tests/` subdirectory, there's some integration tests.
+
+## //tvix/tests:runVM
+A script spinning up a `tvix-store virtiofs` daemon, then starting a cloud-
+hypervisor VM.
+
+The cloud-hypervisor VM is using a (semi-)minimal kernel image with virtiofs
+support, and a custom initrd (using u-root). It supports various command line
+options, to be able to do VM tests, act as an interactive shell or exec a binary
+from a closure.
+
+It supports the following env vars:
+ - `CH_NUM_CPUS=1` controls the number of CPUs available to the VM
+ - `CH_MEM_SIZE=512M` controls the memory availabe to the VM
+ - `CH_CMDLINE=` controls the kernel cmdline (which can be used to control the
+   boot)
+
+### Usage
+First, ensure you have `tvix-store` in `$PATH`, as that's what `run-tvix-vm`
+expects:
+
+Assuming you ran `cargo build --profile=release-with-debug` before, and are in
+the `tvix` directory:
+
+```
+export PATH=$PATH:$PWD/target/release-with-debug
+```
+
+Secondly, configure tvix to use the local backend:
+
+```
+export BLOB_SERVICE_ADDR=sled://$PWD/blobs.sled
+export DIRECTORY_SERVICE_ADDR=sled://$PWD/directories.sled
+export PATH_INFO_SERVICE_ADDR=sled://$PWD/pathinfo.sled
+```
+
+Potentially copy some data into tvix-store (via nar-bridge):
+
+```
+mg run //tvix:store -- daemon &
+mg run //tvix:nar-bridge -- &
+rm -Rf ~/.cache/nix; nix copy --to http://localhost:9000\?compression\=none $(mg build //third_party/nixpkgs:hello)
+pkill nar-bridge; pkill tvix-store
+```
+
+#### Interactive shell
+Run the VM like this:
+
+```
+CH_CMDLINE=tvix.shell mg run //tvix/tests:runVM --
+```
+
+You'll get dropped into an interactive shell, from which you can do things with
+the store:
+
+```
+  ______      _         ____      _ __
+ /_  __/   __(_)  __   /  _/___  (_) /_
+  / / | | / / / |/_/   / // __ \/ / __/
+ / /  | |/ / />  <   _/ // / / / / /_
+/_/   |___/_/_/|_|  /___/_/ /_/_/\__/
+
+/# ls -la /nix/store/
+dr-xr-xr-x root 0 0   Jan  1 00:00 .
+dr-xr-xr-x root 0 989 Jan  1 00:00 aw2fw9ag10wr9pf0qk4nk5sxi0q0bn56-glibc-2.37-8
+dr-xr-xr-x root 0 3   Jan  1 00:00 jbwb8d8l28lg9z0xzl784wyb9vlbwss6-xgcc-12.3.0-libgcc
+dr-xr-xr-x root 0 82  Jan  1 00:00 k8ivghpggjrq1n49xp8sj116i4sh8lia-libidn2-2.3.4
+dr-xr-xr-x root 0 141 Jan  1 00:00 mdi7lvrn2mx7rfzv3fdq3v5yw8swiks6-hello-2.12.1
+dr-xr-xr-x root 0 5   Jan  1 00:00 s2gi8pfjszy6rq3ydx0z1vwbbskw994i-libunistring-1.1
+```
+
+Once you exit the shell, the VM will power off itself.
+
+#### Execute a specific binary
+Run the VM like this:
+
+```
+hello_cmd=$(mg build //third_party/nixpkgs:hello)/bin/hello
+CH_CMDLINE=tvix.run=$hello_cmd mg run //tvix/tests:runVM --
+```
+
+Observe it executing the file (and closure) from the tvix-store:
+
+```
+[    0.277486] Run /init as init process
+  ______      _         ____      _ __
+ /_  __/   __(_)  __   /  _/___  (_) /_
+  / / | | / / / |/_/   / // __ \/ / __/
+ / /  | |/ / />  <   _/ // / / / / /_
+/_/   |___/_/_/|_|  /___/_/ /_/_/\__/
+
+Hello, world!
+2023/09/24 21:10:19 Nothing left to be done, powering off.
+[    0.299122] ACPI: PM: Preparing to enter system sleep state S5
+[    0.299422] reboot: Power down
+```
+
+#### Execute a NixOS system closure
+It's also possible to invoke a system closure. To do this, tvix-init honors the
+init= cmdline option, and will switch_root to it.
+
+
+```
+CH_CMDLINE=init=/nix/store/…-nixos-system-…/init mg run //tvix/tests:runVM --
+```
+
+```
+  ______      _         ____      _ __
+ /_  __/   __(_)  __   /  _/___  (_) /_
+  / / | | / / / |/_/   / // __ \/ / __/
+ / /  | |/ / />  <   _/ // / / / / /_
+/_/   |___/_/_/|_|  /___/_/ /_/_/\__/
+
+2023/09/24 21:16:43 switch_root: moving mounts
+2023/09/24 21:16:43 switch_root: Skipping "/run" as the dir does not exist
+2023/09/24 21:16:43 switch_root: Changing directory
+2023/09/24 21:16:43 switch_root: Moving /
+2023/09/24 21:16:43 switch_root: Changing root!
+2023/09/24 21:16:43 switch_root: Deleting old /
+2023/09/24 21:16:43 switch_root: executing init
+
+<<< NixOS Stage 2 >>>
+
+[    0.322096] booting system configuration /nix/store/g657sdxinpqfcdv0162zmb8vv9b5c4c5-nixos-system-client-23.11.git.82102fc37da
+running activation script...
+setting up /etc...
+starting systemd...
+[    0.980740] systemd[1]: systemd 253.6 running in system mode (+PAM +AUDIT -SELINUX +APPARMOR +IMA +SMACK +SECCOMP +GCRYPT -GNUTLS +OPENSSL +ACL +BLKID +CURL +ELFUTILS +FIDO2 +IDN2 -IDN +IPTC +KMOD +LIBCRYPTSETUP +LIBFDISK +PCRE2 -PWQUALITY +P11KIT -QRENCODE +TPM2 +BZIP2 +LZ4 +XZ +ZLIB +ZSTD +BPF_FRAMEWORK -XKBCOMMON +UTMP -SYSVINIT default-hierarchy=unified)
+```
+
+This effectively replaces the NixOS Stage 1 entirely.
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