Empty `ephemerals` inside `commands`

[Aphosis]

Hello ! We had an issue internally after witching to Rez 3.4.0, where sometimes the ephemerals binding inside commands would be empty.

This was not the case for context.resolved_ephemerals, nor for the created REZ_USED_EPH_RESOLVE and REZ_EPH_<PKG>_REQUEST environment variables.

This does happen (or not) consistently for any given request, but does not happen for every request, if that makes sense.

One of the factors I could determine was if there was another late bound function in the package.

Environment

• OS: Windows
• Rez version: 3.4.0
• Rez python version: Python 3.13.8

To Reproduce

I wrote a small script to reproduce the issue.

The script creates a simple package that accesses ephemerals inside commands and has a late bound function, and marks whether it found a particular ephemeral.

It then resolves a context with this package and the expected ephemeral, and compares what was seen in commands with the actual resolution (the context resolved_ephemerals and environment variables injected by Rez on resolution).

You can run it with rez python ./path/to/script.py.

import tempfile
from pathlib import Path

from rez.resolved_context import ResolvedContext

PACKAGE_PY = """
name = "foo"
version = "1.0"

@late()
def requires():
    return []

def commands():
    if "myeph" in ephemerals:
        env.EPH_SEEN_IN_COMMANDS = "1"
    else:
        env.EPH_SEEN_IN_COMMANDS = "0"
"""


def main():
    with tempfile.TemporaryDirectory(prefix="repro_case_empty_ephemerals_") as temp:
        package_repository = Path(temp)

        package_definition = package_repository / "foo" / "1.0" / "package.py"

        package_definition.parent.mkdir(parents=True, exist_ok=True)
        package_definition.write_text(PACKAGE_PY)

        context = ResolvedContext(
            ["foo", ".myeph-1"], package_paths=[str(package_repository)]
        )
        environ = context.get_environ()

        from_context = context.resolved_ephemerals
        from_env = environ.get("REZ_USED_EPH_RESOLVE")
        seen_in_commands = environ.get("EPH_SEEN_IN_COMMANDS")

        print(f"Ephemerals from `context.resolved_ephemerals`: {from_context}")
        print(f"Ephemerals from `REZ_USED_EPH_RESOLVE`: {from_env}")
        print(f"Ephemeral seen in `commands`: {seen_in_commands}")

        did_resolve = bool(from_context) and bool(from_env)

        if did_resolve and seen_in_commands != "1":
            print(
                "Ephemeral was resolved but absent from `ephemerals` inside `commands`"
            )


if __name__ == "__main__":
    main()

Expected behavior

An ephemerals binding matching context.resolved_ephemerals and the associated environment variables.

Actual behavior

Empty ephemerals binding.

Related Issues/PRs

• Ephemerals should be available in late binding functions #1739
• feat: add ephemerals to the list of objects available in late functions #2117

Regression

The bug only affects the ephemerals binding, and is seemingly caused by the recent change introduced in #2117.

Internally, we found a few possible workarounds (such as using context.resolved_ephemerals in a late bound arbitrary attribute), and are working on a fix. It will probably be a patch to rez.resolved_context.ResolvedContext._get_pre_resolve_bindings that avoids caching ephemerals with other bindings, as ephemerals can be filled during the resolution.

[maxnbk]

and are working on a fix

To clarify, are you saying that you are working on a fix for your own group, or you are working on a PR to submit that would resolve the issue? Just asking so that I know if this is something that I should look into fixing myself or wait for a PR, to avoid duplicating work.

[Aphosis]

and are working on a fix

To clarify, are you saying that you are working on a fix for your own group, or you are working on a PR to submit that would resolve the issue? Just asking so that I know if this is something that I should look into fixing myself or wait for a PR, to avoid duplicating work.

I can submit a PR when we confirm the fix is working on our end, considering summer vacations are right around the corner it may not be before a few weeks though.

But I'll keep this issue updated if I can submit something before then!

[Aphosis]

I opened #2174 to address the issue, it contains only the bugfix for now (and no tests) so I set it to draft.