fix(flagd): use FLAGD_SYNC_PORT for in-process provider with backwards compatibility

[MridulTailor]

Fixes #318

This PR

Updates the in-process provider to use FLAGD_SYNC_PORT as the primary environment variable for port configuration, while maintaining backwards compatibility with FLAGD_PORT as a fallback. This aligns the Python SDK with the flagd specification and other OpenFeature SDKs.

Changes made:

• Added ENV_VAR_SYNC_PORT = "FLAGD_SYNC_PORT" constant to config.py
• Updated port initialization logic in Config.__init__:
  • In-process mode: FLAGD_SYNC_PORT → FLAGD_PORT (fallback) → DEFAULT_PORT_IN_PROCESS (8015)
  • RPC mode: FLAGD_PORT → DEFAULT_PORT_RPC (8013) (unchanged)
  • Explicit port parameter always takes precedence
• Added 5 new test cases in test_config.py:
  • test_in_process_uses_sync_port - Verifies FLAGD_SYNC_PORT is used when set
  • test_in_process_fallback_to_port - Verifies FLAGD_PORT fallback for backwards compatibility
  • test_in_process_sync_port_priority - Verifies FLAGD_SYNC_PORT takes priority when both are set
  • test_rpc_ignores_sync_port - Verifies RPC mode ignores FLAGD_SYNC_PORT
  • test_in_process_default_port_when_no_env_var - Verifies default port when no env vars are set
• Updated README.md configuration table to document the new environment variable

Related Issues

Fixes #318

Parent issue: open-feature/flagd#1573
Testbed issue: open-feature/flagd-testbed#266

Notes

Backwards Compatibility:

• Existing code using FLAGD_PORT for in-process mode continues to work
• New code can use FLAGD_SYNC_PORT for in-process mode (recommended)
• RPC mode behavior unchanged

How to test

Run the unit tests:

cd providers/openfeature-provider-flagd
uv run pytest tests/test_config.py -v
# Expected: 13 passed

uv run pytest tests --ignore=tests/e2e -v
# Expected: 181 passed

[gemini-code-assist]

Summary of Changes

Hello @MridulTailor, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refines the port configuration mechanism for the flagd Python provider, specifically enhancing the in-process resolver. It introduces FLAGD_SYNC_PORT to align with the broader flagd specification, while carefully preserving backward compatibility by allowing FLAGD_PORT to serve as a fallback. The changes ensure a more consistent and robust approach to port management across different operational modes.

Highlights

• New Environment Variable: Introduced FLAGD_SYNC_PORT as the primary environment variable for configuring the port in in-process mode, aligning with the flagd specification.
• Backwards Compatibility: Ensured that FLAGD_PORT continues to function as a fallback for in-process mode, preventing breaking changes for existing configurations.
• Updated Port Resolution Logic: Modified the Config initialization to prioritize FLAGD_SYNC_PORT for in-process, fall back to FLAGD_PORT, and maintain FLAGD_PORT for RPC mode.
• Comprehensive Testing: Added five new unit tests to validate the new port configuration hierarchy and ensure correct behavior in various scenarios.
• Documentation Update: Updated the README.md to reflect the new FLAGD_SYNC_PORT environment variable and its usage.

Changelog

• providers/openfeature-provider-flagd/README.md
  • Updated the configuration table to document FLAGD_SYNC_PORT for in-process mode and clarify FLAGD_PORT's role for RPC or as a fallback.
• providers/openfeature-provider-flagd/src/openfeature/contrib/provider/flagd/config.py
  • Added ENV_VAR_SYNC_PORT constant.
  • Modified the Config.__init__ method to implement a new port resolution hierarchy: FLAGD_SYNC_PORT takes precedence for in-process mode, followed by FLAGD_PORT as a fallback, and finally DEFAULT_PORT_IN_PROCESS.
  • Ensured RPC mode continues to use FLAGD_PORT exclusively.
  • Updated the __init__ signature to include PLR0915 for line length.
• providers/openfeature-provider-flagd/tests/test_config.py
  • Imported ENV_VAR_SYNC_PORT.
  • Added five new test cases: test_in_process_uses_sync_port, test_in_process_fallback_to_port, test_in_process_sync_port_priority, test_rpc_ignores_sync_port, and test_in_process_default_port_when_no_env_var to thoroughly test the new port resolution logic.

Activity

• No human activity (comments, reviews, etc.) has occurred on this pull request yet.

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[gemini-code-assist]

Code Review

This pull request updates the in-process provider to use FLAGD_SYNC_PORT for port configuration, with backwards compatibility for FLAGD_PORT. The changes are logical and well-tested. I've provided a couple of suggestions to improve code readability and documentation formatting.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.55%. Comparing base (80da6b9) to head (dba8d50).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #345      +/-   ##
==========================================
- Coverage   96.55%   95.55%   -1.00%     
==========================================
  Files           5       16      +11     
  Lines         174      878     +704     
==========================================
+ Hits          168      839     +671     
- Misses          6       39      +33     

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[aepfli]

Thank you, nice addition, i feel like the gemini input is a good one, which we should implement

[MridulTailor]

I thought so too, I will resolve it right away.

[aepfli]

/gemini review

[gemini-code-assist]

Code Review

The changes correctly implement the priority for FLAGD_SYNC_PORT in in-process mode while maintaining backwards compatibility with FLAGD_PORT. I have suggested a simplification for the port initialization logic in Config.__init__ which reduces verbosity and fixes a minor regression where ResolverType.FILE would default to the RPC port instead of the in-process port.