[CICP-51496] Retire legacy IdealState mode

[sjainit]

Issues

Campaign: https://linkedin.atlassian.net/browse/CICP-51496

Description

Warning

Do not merge or deploy until the downstream migrations are released and legacy-only records, obsolete mode aliases, and legacy mode rules have been audited/migrated. Opening this PR does not satisfy those prerequisites.

Retire the deprecated IdealState mode configuration and make REBALANCE_MODE the only supported mode field.

• Remove IdealStateProperty.IDEAL_STATE_MODE, IdealStateModeProperty, the deprecated getter/setter, legacy normalization/denormalization, and the now-unused LEGACY_TASK_REBALANCERS constant.
• Write only the modern field. Read it without mutating records or consulting legacy metadata.
• Preserve the effective SEMI_AUTO default for missing/invalid modern values, as explicitly requested. Respect every valid modern enum value, including explicit NONE.
• Parse modern enum names only. Invalid inputs, including retired AUTO/AUTO_REBALANCE aliases, are logged and return the caller's existing default.
• Exclude legacy metadata from topology change detection, migrate in-repo fixtures/rules/examples, and remove the obsolete resource-summary row from the UI.

Raw legacy fields are preserved as opaque metadata, not deleted or synchronized. Generic raw-record APIs continue accepting unknown fields. The old admin-webapp constant named IDEAL_STATE_MODE is retained because its value is the still-supported HTTP argument "mode", not the retired stored configuration key.

Merge/release prerequisites:

• Merge and release the relevant downstream migrations: linkedin-multiproduct/espresso#3178, linkedin-multiproduct/lipy-helix#274, linkedin-multiproduct/lipy-venice-libs#618, and linkedin-multiproduct/lipy-ambry-clustermap#840. Reader upgrades must precede modern-only writers.
• Complete the remaining downstream-reference classification, including the Databus deprecated API reference and other writer/tooling references. These four PRs are an initial batch, not proof that every caller is migrated.
• Refresh the legacy-only record audit and migrate affected persisted records under separately approved operational scope. A previous saved census found three legacy-only endpoint/resource observations; that historical result is not a current or exhaustive census.
• Audit explicit NONE, invalid modern values, obsolete string aliases, and any IdealStateRule! filters referring to IDEAL_STATE_MODE; replace fallback-dependent settings with explicit intended modern values.

No live configuration edits, cluster operations, or downstream deployments are included.

Tests

• Local code review completed
• Added model coverage for all modern modes, a 66-case modern/legacy matrix, non-mutating reads, opaque-field preservation, parser defaults, and removed public API shape.
• Added topology-trimmer and persisted admin-payload coverage; migrated controller/task/rule fixtures.
• Extended REST creation/readback coverage for modern-only JSON and added four UI model regressions.

Java 11 native Maven validation:

mvn -B -ntp -pl helix-rest -am test \
  '-Dtest=TestIdealState,TestHelixPropoertyTimmer,TestBestPossibleCalcStageCompatibility,TestEvacuateInstanceTaskAssignment,TestFixedTargetedTaskAssignmentCalculator,TestTargetedTaskStateChange,TestZkHelixAdmin#testAddResourceWritesOnlyModernRebalanceMode,TestInvalidResourceRebalance,TestMessageThrottle2,TestAutoIsWithEmptyMap,TestResourceConfig,TestRebalanceConfig,TestResourceAccessor#testGetResources+testGetResource+testAddResources+testResourceConfig+testIdealState' \
  -Dsurefire.failIfNoSpecifiedTests=false -DfailIfNoTests=false

Results on dev base d3638bac5 (including #324): 145 core cases and 5 REST cases passed, with zero failures/errors/skips. Both Java 8 and Java 11 class outputs were checked for removal of the old APIs/enum.

UI validation with Node 20 and Yarn 1.22:

yarn test --runInBand --runTestsByPath src/app/resource/shared/resource.model.spec.ts \
  --coverageReporters=html --coverageReporters=lcov \
  --coverageReporters=json --coverageReporters=text
yarn type:check
yarn exec prettier -- --check src/app/resource/shared/resource.model.ts \
  src/app/resource/shared/resource.model.spec.ts \
  src/app/resource/resource-detail/resource-detail.component.html
yarn exec eslint -- src/app/resource/shared/resource.model.ts \
  src/app/resource/shared/resource.model.spec.ts \
  src/app/resource/resource-detail/resource-detail.component.html

Results: 4 UI cases passed; type-checking, touched-file formatting/lint and git diff --check passed. The standard ignored sample server config was created with yarn copy:config. Coverage remained enabled; built-in output formats avoid the existing misconfigured jest-html-reporters coverage-reporter entry. Dependency manifests and lockfiles are unchanged.

These are focused validations, not a full backend/frontend suite or a live migration rehearsal.

Changes that Break Backward Compatibility (Optional)

• Removed Java symbols are source- and binary-incompatible. Rebuild/release downstream consumers before upgrading.
• Modern setters no longer emit compatibility metadata; old readers that require the field must already be upgraded.
• Legacy-only FULL_AUTO/CUSTOMIZED records no longer recover their mode from the old field. Missing/invalid modern values now use SEMI_AUTO independently of legacy metadata.
• Explicit NONE is preserved rather than normalized through legacy/default mode. It does not select an operational rebalancer.
• Reads no longer synthesize or repair mode fields in memory. Existing stale legacy fields remain unchanged even after a modern setter call.
• The string parser no longer translates legacy aliases. In particular, an admin call using AUTO_REBALANCE now logs an invalid value and takes its existing default rather than selecting FULL_AUTO.
• The UI no longer exposes the idealStateMode summary property/row.

Backout must account for newly written modern-only records: reverting binaries alone is insufficient for readers that still require legacy metadata. Coordinate compatible readers and the owning teams' approved snapshot/config restoration procedures. Do not infer legacy values from all modern modes: legacy AUTO is lossy for TASK/USER_DEFINED.

Documentation (Optional)

README compatibility guidance documents defaults, the migration mapping, ignored raw metadata, source/binary breaks, and operational prerequisites. IdealState Javadocs and active examples were updated. Historical versioned website content and generated documentation snapshots were not rewritten.

Commits

The commit references CICP-51496, uses an imperative subject, and includes the Copilot co-author trailer. No unrelated main-checkout changes are included.

Code Quality

The change reuses the existing enum-field reader and modern mode API, narrows parser exception handling, and preserves repository conventions. UI files were formatted with the repository's Prettier and passed ESLint.

🤖 Generated with GitHub Copilot CLI