“OSError: Installation of taplo failed” in image rebuilds

[delan]

ci2.servo.org servo-ubuntu2204:

$ systemctl stop monitor
$ virsh shutdown servo-ubuntu2204
$ mount -r /dev/zvol/tank/base/servo-ubuntu2204-part1 /mnt/zvol
$ chroot /mnt/zvol /usr/bin/env -i /bin/bash

$ journalctl -t rc.local
[...]
Mar 05 02:42:54 ubuntu rc.local[9985]: error: toolchain '1.85.0-x86_64-unknown-linux-gnu' is not installed
Mar 05 02:42:54 ubuntu rc.local[9985]: help: run `rustup toolchain install 1.85.0-x86_64-unknown-linux-gnu` to install it
Mar 05 02:42:54 ubuntu rc.local[4122]:  * Setting up virtual environment...
Mar 05 02:42:54 ubuntu rc.local[4122]:  * Installing Python requirements...
Mar 05 02:42:54 ubuntu rc.local[4122]: Installing missing dependencies...
Mar 05 02:42:54 ubuntu rc.local[4122]:  * Installing taplo...
Mar 05 02:42:54 ubuntu rc.local[4122]: Traceback (most recent call last):
Mar 05 02:42:54 ubuntu rc.local[4122]:   File "/a/servo/servo/./mach", line 52, in <module>
Mar 05 02:42:54 ubuntu rc.local[4122]:     main(sys.argv)
Mar 05 02:42:54 ubuntu rc.local[4122]:   File "/a/servo/servo/./mach", line 45, in main
Mar 05 02:42:54 ubuntu rc.local[4122]:     sys.exit(mach_bootstrap.bootstrap_command_only(topdir))
Mar 05 02:42:54 ubuntu rc.local[4122]:              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Mar 05 02:42:54 ubuntu rc.local[4122]:   File "/a/servo/servo/python/mach_bootstrap.py", line 174, in bootstrap_command_only
Mar 05 02:42:54 ubuntu rc.local[4122]:     servo.platform.get().bootstrap(force, skip_platform, skip_lints)
Mar 05 02:42:54 ubuntu rc.local[4122]:   File "/a/servo/servo/python/servo/platform/base.py", line 64, in bootstrap
Mar 05 02:42:54 ubuntu rc.local[4122]:     installed_something |= self.install_taplo(force)
Mar 05 02:42:54 ubuntu rc.local[4122]:                            ^^^^^^^^^^^^^^^^^^^^^^^^^
Mar 05 02:42:54 ubuntu rc.local[4122]:   File "/a/servo/servo/python/servo/platform/base.py", line 77, in install_taplo
Mar 05 02:42:54 ubuntu rc.local[4122]:     raise EnvironmentError("Installation of taplo failed.")
Mar 05 02:42:54 ubuntu rc.local[4122]: OSError: Installation of taplo failed.

ci1.servo.org servo-macos13:

[delan]

This seems to be related to rust-lang/rustup#3985, which landed in rustup 1.28.0:

• rustup will no longer automatically install the active toolchain if it is not installed.
  • To ensure its installation, run rustup toolchain install with no arguments.
  • The following command installs the active toolchain both before and after this change:

    rustup show active-toolchain || rustup toolchain install
    # Or, on older versions of PowerShell:
    rustup show active-toolchain; if ($LASTEXITCODE -ne 0) { rustup toolchain install }

[delan]

The breaking change will be reverted in rustup 1.28.1 (rust-lang/rustup#4211), but the installer is not available yet:

This is a patch release to restore the automatic install behavior by default.

• Automatic install is enabled by default but can be opted out by setting RUSTUP_AUTO_INSTALL environment variable to 0.

[delan]

Fixed in b1700d0 + servo/servo#35795.