Currently, by default, rules_python immediately fails when Bazel is run as root. The reasoning behind this involves .pyc files being generated for hermetic toolchains when they're first used, causing cache misses; to work around this, rules_python opts to make the toolchain installation directory read-only, but running Bazel as root would circumvent this. So rules_python actively detects if the current user is root, and hard fails. This check can be disabled by the root module by setting `python.override(ignore_root_user_error=True)`. (See more context in the linked issues/PRs.)

This causes a reverberating effect across the Bazel ecosystem, as rules_python is essentially a dependency of every single Bazel project through protobuf. Effectively, any Bazel project wishing to run as root need to add the override tag above, even if they don't have anything to do with Python at all.

This PR changes the default value of the `ignore_root_user_error` to True instead. Besides, it now unconditionally tries to make the toolchain installation directory read-only, and only outputs a warning if it's detected that the current user is root.

See previous discussions at #713, #749, #907, #1008, #1169, etc.

Fixes #1169.

dcode pushed a commit to dcode/rules_python that referenced this pull request

…-contrib#2636)

Currently, by default, rules_python immediately fails when Bazel is run
as root. The reasoning behind this involves .pyc files being generated
for hermetic toolchains when they're first used, causing cache misses;
to work around this, rules_python opts to make the toolchain
installation directory read-only, but running Bazel as root would
circumvent this. So rules_python actively detects if the current user is
root, and hard fails. This check can be disabled by the root module by
setting `python.override(ignore_root_user_error=True)`. (See more
context in the linked issues/PRs.)

This causes a reverberating effect across the Bazel ecosystem, as
rules_python is essentially a dependency of every single Bazel project
through protobuf. Effectively, any Bazel project wishing to run as root
need to add the override tag above, even if they don't have anything to
do with Python at all.

This PR changes the default value of the `ignore_root_user_error` to
True instead. Besides, it now unconditionally tries to make the
toolchain installation directory read-only, and only outputs a warning
if it's detected that the current user is root.

See previous discussions at bazel-contrib#713, bazel-contrib#749, bazel-contrib#907, bazel-contrib#1008, bazel-contrib#1169, etc.

Fixes bazel-contrib#1169.

---------

Co-authored-by: Richard Levasseur <rlevasseur@google.com>

github-merge-queue bot pushed a commit that referenced this pull request

Previously
[#2636](#2636) changed
the semantics of `ignore_root_user_error` from "ignore" to "warning".
This is now flipped back to ignoring the issue, and will only emit a
warning when the attribute is set `False`.

This does also change the semantics of what #2636 did by flipping the
attribute, as now there is no warning, and the user would have to
explicitly set it to `False` (they don't want to ignore the error) to
see the warning.

Co-authored-by: Richard Levasseur <rlevasseur@google.com>