8239f32b62
Rename the nar-bridge CLI to nar-bridge-http, because it's the one spinning up an http server. Change-Id: I0fb75c50e4299272a128dd5ecaa4be8f06fa3dbe Reviewed-on: https://cl.tvl.fyi/c/depot/+/9538 Reviewed-by: Connor Brewster <cbrewster@hey.com> Tested-by: BuildkiteCI Autosubmit: flokli <flokli@flokli.de>
136 lines
4.5 KiB
Markdown
136 lines
4.5 KiB
Markdown
# tvix/boot
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This directory provides tooling to boot VMs with /nix/store provided by
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virtiofs.
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In the `tests/` subdirectory, there's some integration tests.
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## //tvix/boot:runVM
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A script spinning up a `tvix-store virtiofs` daemon, then starting a cloud-
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hypervisor VM.
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The cloud-hypervisor VM is using a (semi-)minimal kernel image with virtiofs
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support, and a custom initrd (using u-root). It supports various command line
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options, to be able to do VM tests, act as an interactive shell or exec a binary
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from a closure.
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It supports the following env vars:
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- `CH_NUM_CPUS=1` controls the number of CPUs available to the VM
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- `CH_MEM_SIZE=512M` controls the memory availabe to the VM
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- `CH_CMDLINE=` controls the kernel cmdline (which can be used to control the
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boot)
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### Usage
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First, ensure you have `tvix-store` in `$PATH`, as that's what `run-tvix-vm`
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expects:
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Assuming you ran `cargo build --profile=release-with-debug` before, and are in
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the `tvix` directory:
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```
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export PATH=$PATH:$PWD/target/release-with-debug
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```
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Secondly, configure tvix to use the local backend:
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```
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export BLOB_SERVICE_ADDR=sled://$PWD/blobs.sled
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export DIRECTORY_SERVICE_ADDR=sled://$PWD/directories.sled
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export PATH_INFO_SERVICE_ADDR=sled://$PWD/pathinfo.sled
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```
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Potentially copy some data into tvix-store (via nar-bridge):
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```
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mg run //tvix:store -- daemon &
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$(mg build //tvix:nar-bridge)/bin/nar-bridge-http &
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rm -Rf ~/.cache/nix; nix copy --to http://localhost:9000\?compression\=none $(mg build //third_party/nixpkgs:hello)
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pkill nar-bridge-http; pkill tvix-store
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```
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#### Interactive shell
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Run the VM like this:
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```
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CH_CMDLINE=tvix.shell mg run //tvix/boot:runVM --
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```
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You'll get dropped into an interactive shell, from which you can do things with
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the store:
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```
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______ _ ____ _ __
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/_ __/ __(_) __ / _/___ (_) /_
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/ / | | / / / |/_/ / // __ \/ / __/
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/ / | |/ / /> < _/ // / / / / /_
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/_/ |___/_/_/|_| /___/_/ /_/_/\__/
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/# ls -la /nix/store/
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dr-xr-xr-x root 0 0 Jan 1 00:00 .
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dr-xr-xr-x root 0 989 Jan 1 00:00 aw2fw9ag10wr9pf0qk4nk5sxi0q0bn56-glibc-2.37-8
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dr-xr-xr-x root 0 3 Jan 1 00:00 jbwb8d8l28lg9z0xzl784wyb9vlbwss6-xgcc-12.3.0-libgcc
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dr-xr-xr-x root 0 82 Jan 1 00:00 k8ivghpggjrq1n49xp8sj116i4sh8lia-libidn2-2.3.4
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dr-xr-xr-x root 0 141 Jan 1 00:00 mdi7lvrn2mx7rfzv3fdq3v5yw8swiks6-hello-2.12.1
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dr-xr-xr-x root 0 5 Jan 1 00:00 s2gi8pfjszy6rq3ydx0z1vwbbskw994i-libunistring-1.1
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```
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Once you exit the shell, the VM will power off itself.
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#### Execute a specific binary
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Run the VM like this:
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```
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hello_cmd=$(mg build //third_party/nixpkgs:hello)/bin/hello
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CH_CMDLINE=tvix.run=$hello_cmd mg run //tvix/boot:runVM --
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```
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Observe it executing the file (and closure) from the tvix-store:
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```
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[ 0.277486] Run /init as init process
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______ _ ____ _ __
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/_ __/ __(_) __ / _/___ (_) /_
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/ / | | / / / |/_/ / // __ \/ / __/
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/ / | |/ / /> < _/ // / / / / /_
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/_/ |___/_/_/|_| /___/_/ /_/_/\__/
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Hello, world!
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2023/09/24 21:10:19 Nothing left to be done, powering off.
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[ 0.299122] ACPI: PM: Preparing to enter system sleep state S5
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[ 0.299422] reboot: Power down
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```
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#### Execute a NixOS system closure
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It's also possible to invoke a system closure. To do this, tvix-init honors the
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init= cmdline option, and will switch_root to it.
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```
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CH_CMDLINE=init=/nix/store/…-nixos-system-…/init mg run //tvix/boot:runVM --
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```
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```
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______ _ ____ _ __
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/_ __/ __(_) __ / _/___ (_) /_
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/ / | | / / / |/_/ / // __ \/ / __/
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/ / | |/ / /> < _/ // / / / / /_
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/_/ |___/_/_/|_| /___/_/ /_/_/\__/
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2023/09/24 21:16:43 switch_root: moving mounts
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2023/09/24 21:16:43 switch_root: Skipping "/run" as the dir does not exist
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2023/09/24 21:16:43 switch_root: Changing directory
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2023/09/24 21:16:43 switch_root: Moving /
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2023/09/24 21:16:43 switch_root: Changing root!
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2023/09/24 21:16:43 switch_root: Deleting old /
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2023/09/24 21:16:43 switch_root: executing init
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<<< NixOS Stage 2 >>>
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[ 0.322096] booting system configuration /nix/store/g657sdxinpqfcdv0162zmb8vv9b5c4c5-nixos-system-client-23.11.git.82102fc37da
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running activation script...
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setting up /etc...
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starting systemd...
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[ 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)
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```
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This effectively replaces the NixOS Stage 1 entirely.
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