1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
# 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/boot: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:$PWD/target/release-with-debug
```
Now, spin up tvix-daemon, connecting to some (local) backends:
```
tvix-store --otlp=false daemon \
--blob-service-addr=objectstore+file://$PWD/blobs \
--directory-service-addr=redb://$PWD/directories.redb \
--path-info-service-addr=redb://$PWD/pathinfo.redb &
```
Copy some data into tvix-store (we use `nar-bridge` for this for now):
```
mg run //tvix:nar-bridge -- --otlp=false &
rm -Rf ~/.cache/nix; nix copy --to http://localhost:9000\?compression\=none $(mg build //third_party/nixpkgs:hello)
pkill nar-bridge
```
By default, the `tvix-store virtiofs` command used in the `runVM` script
connects to a running `tvix-store daemon` via gRPC - in which case you want to
keep `tvix-store daemon` running.
In case you want to have `tvix-store virtiofs` open the stores directly, kill
`tvix-store daemon` too, and export the addresses from above:
```
pkill tvix-store
export BLOB_SERVICE_ADDR=objectstore+file://$PWD/blobs
export DIRECTORY_SERVICE_ADDR=redb://$PWD/directories.redb
export PATH_INFO_SERVICE_ADDR=redb://$PWD/pathinfo.redb
```
#### Interactive shell
Run the VM like this:
```
CH_CMDLINE=tvix.shell mg run //tvix/boot: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/boot: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
```
#### Boot a NixOS system closure
It's also possible to boot a system closure. To do this, tvix-init honors the
init= cmdline option, and will `switch_root` to it.
Make sure to first copy that system closure into tvix-store,
using a similar `nix copy` comamnd as above.
```
CH_CMDLINE=init=/nix/store/…-nixos-system-…/init mg run //tvix/boot: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.
|
