feat: support SDK version requirements

[bhashemian]

Add optional holoscan_sdk.required_versions to metadata.json to automatically select the latest published stable SDK base image matching the requirements and selected CUDA/GPU variant.

Supports Python-style constraints:

• Ranges: ">=4.1,<5": comma-separated conditions must all match.
• Wildcards: "4.1.*".
• Alternatives: ["4.1.0", "4.3.*"]": any entry may match.

When present, required_versions supersedes minimum_required_version (kept only for backward compatibility) in the same metadata object. Existing minimum-only metadata and explicit SDK/image overrides retain their behavior. Uses packaging for parsing and validation.

Summary by CodeRabbit

• New Features

  • Projects can specify SDK version ranges, wildcards, or alternatives to automatically select the latest compatible published SDK for container builds.
  • Standalone applications can be recognized using SDK version requirements without specifying a minimum version.
  • Explicit base-image settings and format overrides take precedence over automatic selection.

• Documentation

  • Updated CLI and configuration guidance to explain SDK requirements and automatic base-image selection.

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Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

OpenSSF Scorecard

Package	Version	Score	Details
pip/packaging	>= 24.2	Unknown	Unknown

Scanned Files

• pyproject.toml

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• tests/unit/conftest.py

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Walkthrough

The CLI now accepts SDK version requirements in project metadata and can select a compatible published SDK version for container builds. It validates requirement specifiers, applies CUDA and GPU eligibility rules, and preserves explicit base-image settings.

Changes

SDK Image Selection

Layer / File(s)	Summary
SDK requirement metadata src/holoscan_cli/metadata/project.schema.json, src/holoscan_cli/metadata/metadata_validator.py, src/holoscan_cli/project_context.py, CONFIGURATION.md, tests/unit/test_metadata_validator.py, tests/unit/test_standalone_application.py	Metadata validation and project discovery now support required_versions as a string or list of strings. The schema requires either required_versions or minimum_required_version.
Published SDK version matching src/holoscan_cli/utils/sdk.py, pyproject.toml, tests/unit/test_sdk_utils.py, tests/unit/test_package_data.py	SDK utilities retrieve and cache registry tags, parse version requirements, and select the highest stable eligible version. The packaging runtime dependency supports requirement parsing. Tests cover matching and registry behavior.
Container base image resolution src/holoscan_cli/container/core.py, src/holoscan_cli/utils/project.py, tests/unit/test_container_core.py, tests/unit/test_lifecycle_commands.py, tests/unit/conftest.py, CLI_REFERENCE.md, CONFIGURATION.md	Container builds use the selected SDK version for the resolved base image and build arguments when automatic selection applies. Explicit base-image settings continue to take precedence. Documentation describes the selection behavior.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~25 minutes

Suggested reviewers: wyli

Merge Risk: ⚪ Minimal · up to a69da

The reviewed changes are mergeable with normal validation; requirements-only metadata follows the supported automatic image-selection path.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding support for SDK version requirements and automatic SDK selection.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Inline comments:
In `@tests/unit/test_container_core.py`:
- Around line 165-169: Update the autouse `_reset_active_project_context`
fixture to preserve and restore the prior `HOLOSCAN_CLI_ROOT` value after each
test that calls `activate_project_context`, including restoring its unset state
when it was initially absent.

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📒 Files selected for processing (15)

• CLI_REFERENCE.md
• CONFIGURATION.md
• pyproject.toml
• src/holoscan_cli/container/core.py
• src/holoscan_cli/metadata/metadata_validator.py
• src/holoscan_cli/metadata/project.schema.json
• src/holoscan_cli/project_context.py
• src/holoscan_cli/utils/project.py
• src/holoscan_cli/utils/sdk.py
• tests/unit/test_container_core.py
• tests/unit/test_lifecycle_commands.py
• tests/unit/test_metadata_validator.py
• tests/unit/test_package_data.py
• tests/unit/test_sdk_utils.py
• tests/unit/test_standalone_application.py

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[wyli]

Non-blocking, fine as a follow-up: could we avoid adding packaging as a runtime dependency?

It is only used to parse and match required_versions, and the package has had no runtime dependencies so far (test_pyproject_has_no_runtime_dependencies; utils/text.py also parses versions itself to avoid packaging). SDK image versions are always plain X.Y.Z, so a small matcher for ==, !=, <, <=, >, >=, ~= and .* covers the documented syntax.

I tried the sketch below on this branch with dependencies = [] and the zero-dependency test restored: all 633 unit tests pass, and selection and validate_json work with packaging imports blocked. It gives the same validity and match results as the current SpecifierSet path for 342 single clauses and 4,000 random two-clause AND/OR combinations, checked against the 33 SDK versions published on NGC plus a few edge cases. It rejects ===, pre-release, post-release, epoch and local-version forms, which SDK tags don't use. The packaging note in CONFIGURATION.md would go too.

If you'd rather keep packaging, >=22 looks sufficient (21.3 still accepts >=4.1.* as a legacy specifier) and is less likely to conflict with pinned or distro copies (Ubuntu 22.04 ships 21.3, 24.04 ships 24.0).

Sketch for src/holoscan_cli/utils/sdk.py

Add import operator, drop the packaging imports, and replace parse_required_versions with:

_REQUIREMENT_RE = re.compile(r"(~=|==|!=|<=|>=|<|>)?\s*v?(\d+(?:\.\d+)*)(\.\*)?")
_COMPARISONS = {
    "==": operator.eq,
    "!=": operator.ne,
    "<=": operator.le,
    ">=": operator.ge,
    "<": operator.lt,
    ">": operator.gt,
}
VersionClause = Callable[[tuple[int, ...]], bool]


def _pad_version(parts: tuple[int, ...], length: int) -> tuple[int, ...]:
    return parts + (0,) * (length - len(parts))


def _version_clause(op: str, release: tuple[int, ...], wildcard: bool) -> VersionClause:
    """Match numeric versions with PEP 440 semantics for this operator subset."""

    def matches(version: tuple[int, ...]) -> bool:
        if wildcard:  # ==4.1.* and !=4.1.* compare the zero-padded prefix.
            same = _pad_version(version, len(release))[: len(release)] == release
            return same if op == "==" else not same
        width = max(len(version), len(release))
        candidate, bound = _pad_version(version, width), _pad_version(release, width)
        if op == "~=":  # ~=4.1.0 means >=4.1.0, ==4.1.*
            return candidate >= bound and candidate[: len(release) - 1] == release[:-1]
        return _COMPARISONS[op](candidate, bound)

    return matches


def parse_required_versions(value: Union[str, list[str]]) -> tuple[tuple[VersionClause, ...], ...]:
    """Parse OR alternatives, each containing ANDed numeric version clauses."""
    alternatives = [value] if isinstance(value, str) else value
    if not isinstance(alternatives, list) or not alternatives:
        raise ValueError("required_versions must be a non-empty string or list of strings.")
    result = []
    for alternative in alternatives:
        if not isinstance(alternative, str) or not alternative.strip():
            raise ValueError("required_versions entries must be non-empty strings.")
        clauses = []
        for clause in alternative.split(","):
            clause = clause.strip()
            if not clause:
                raise ValueError("required_versions cannot contain an empty version clause.")
            match = _REQUIREMENT_RE.fullmatch(clause)
            op = (match[1] or "==") if match else ""
            if (
                not match
                or (match[3] and op not in ("==", "!="))
                or (op == "~=" and "." not in match[2])
            ):
                raise ValueError(f"Invalid required_versions specifier: {alternative!r}.")
            release = tuple(map(int, match[2].split(".")))
            clauses.append(_version_clause(op, release, bool(match[3])))
        result.append(tuple(clauses))
    return tuple(result)

In select_sdk_version, the match becomes:

        if not all(
            any(all(clause(key) for clause in clauses) for clauses in alternatives)
            for alternatives in constraints
        ):
            continue