bug: discovery parsing errors handling

[denis256]

Description

• improved detection of legacy fields during HCL parsing
• discovery: skip include-only configs; cleaner suppressed-errors logging (no %w/%!w); fixes Unrecoverable parse error for ./terragrunt.hcl: Could not find Terragrunt configuration settings in ./terragrunt.hcl #4983
• Runner pool: correct log formatting by calling Path()
• Tests: add run-all repro variant; assert no cryptic logs; update bare-include strict message; mark one deprecation fixture as known-bad in parse sweep

Before this fix:

After this fix:

Fixes #4983.

TODOs

Read the Gruntwork contribution guidelines.

• I authored this code entirely myself
• I am submitting code based on open source software (e.g. MIT, MPL-2.0, Apache)]
• I am adding or upgrading a dependency or adapted code and confirm it has a compatible open source license
• Update the docs.
• Run the relevant tests successfully, including pre-commit checks.
• Include release notes. If this PR is backward incompatible, include a migration guide.

Release Notes (draft)

Added / Removed / Updated [X].

Migration Guide

Summary by CodeRabbit

• Bug Fixes

  • Improved detection and error reporting for deprecated configuration syntax (earlier, clearer errors for exposed includes).
  • Better handling of include-only/no-settings configs when parse-error suppression is enabled to avoid fatal failures.
  • Clarified include-block deprecation message for unlabeled includes.

• Tests

  • Added regression tests covering deprecated inputs in exposed includes and run-all scenarios with generate/expose behavior.

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Project	Deployment	Preview	Comments	Updated (UTC)
terragrunt-docs	Ready	Preview	Comment	Oct 30, 2025 2:59pm

[coderabbitai]

📝 Walkthrough

Walkthrough

Early deprecation detection was added to partial config parsing to fail fast on deprecated syntax in included configs. Discovery now treats include-only/no-settings parse failures as non-fatal when suppression is enabled. Additional test fixtures and regression tests were added, and minor Path -> Path() refactors applied.

Changes

Cohort / File(s)	Summary
Early deprecation detection in partial parsing config/config_partial.go	Invoke DetectDeprecatedConfigurations early in PartialParseConfig and return its error immediately to block deprecated syntax before further parsing.
Discovery error handling enhancements internal/discovery/discovery.go	Add containsNoSettingsError() helper; on PartialParse errors, if suppression is enabled and error indicates no Terragrunt settings, treat as non-fatal (log debug and skip) and improve debug/error logging. Also add nil-check in DiscoverDependencies.
Path method refactoring internal/runner/runnerpool/controller.go	Replace direct Path field accesses with Path() method calls in logs, lookups, and result handling.
Deprecated inputs test fixture test/fixtures/parsing/exposed-include-with-deprecated-inputs/* \test/fixtures/parsing/exposed-include-with-deprecated-inputs/root.hcl`, `.../compcommon.hcl`, `.../child/terragrunt.hcl`, `.../dep/terragrunt.hcl``	Add fixture exercising exposed include with deprecated dependency.*.inputs.* usage and a mock dependency.
Run-all with generate test fixture test/fixtures/regressions/parsing-run-all-with-generate/* \root.hcl`, `services/test1/{main.tf, terragrunt.hcl}`, `services-info/{main.tf, terragrunt.hcl}``	Add fixtures for run --all scenarios with generate blocks, provider generation, service module outputs, and a services-info consumer.
Integration parse test update test/integration_parse_test.go	Mark fixtures/parsing/exposed-include-with-deprecated-inputs/compcommon.hcl as known bad (skip full parse).
Regression tests test/integration_regressions_test.go	Add tests: TestExposedIncludeWithDeprecatedInputsSyntax, TestRunAllWithGenerateAndExpose, and TestRunAllWithGenerateAndExpose_WithProviderCacheAndExcludeExternal.
Strict mode test message update test/integration_strict_test.go	Update expected error message for bare include strict-mode tests to deprecation wording for unlabeled include blocks.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant PartialParseConfig
    participant DetectDeprecated
    participant Parser

    Client->>PartialParseConfig: Request partial parse (included config)
    PartialParseConfig->>DetectDeprecated: Check for deprecated syntax
    alt deprecated syntax found
        DetectDeprecated-->>PartialParseConfig: Return deprecation error
        PartialParseConfig-->>Client: Return error (fail fast)
    else no deprecated syntax
        DetectDeprecated-->>PartialParseConfig: OK
        PartialParseConfig->>Parser: Continue parsing/decoding
        Parser-->>Client: Return partial config
    end

Loading

sequenceDiagram
    participant Discovery
    participant PartialParse
    participant ErrorChecker
    participant Storage

    Discovery->>PartialParse: PartialParse included file
    alt PartialParse returns error
        PartialParse-->>ErrorChecker: Error
        ErrorChecker->>ErrorChecker: containsNoSettingsError(err)?
        alt suppression enabled && no-settings error
            ErrorChecker->>Discovery: Log debug, treat as non-fatal
            Discovery->>Storage: Do not store partial config (skip)
            Discovery-->>Client: Continue discovery without this include
        else
            ErrorChecker-->>Discovery: Propagate error
        end
    else success
        PartialParse-->>Discovery: Store partial config
    end

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

• Pay extra attention to:
  • The early call to DetectDeprecatedConfigurations in config/config_partial.go (ensure it doesn't change intended parsing order for other checks).
  • containsNoSettingsError() matching/unwrapping logic and the conditional suppression path in internal/discovery/discovery.go.
  • All places where .Path was replaced with .Path() in internal/runner/runnerpool/controller.go to ensure no behavioral changes in map keys or logging formats.
  • Added test fixtures and new tests for correctness and expected failure modes.

Possibly related PRs

• bug: reference of dependency outputs in generate #4994 — Modifies partial parsing and discovery flow; touches similar PartialParseConfig and discovery paths.
• fix: Prevent parse errors when using read_terragrunt_config() during discovery #4956 — Changes discovery parsing/error suppression behavior that overlaps discovery.go logic here.
• fix: Fixing excessive warning for dependency input usage #3879 — Addresses deprecated dependency.inputs handling and partial-parse behavior relevant to these tests.

Suggested reviewers

• yhakbar
• levkohimins
• wakeful

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The pull request title "bug: discovery parsing errors handling" directly and specifically summarizes the main change focus, which is improving error handling and logging in the discovery parsing process. The title accurately reflects the core improvements to error detection and reporting mechanisms, particularly addressing the issue of cryptic error messages and formatting artifacts in discovery logs. The title is concise, specific, and clearly communicates the primary objective without vague terminology.
Linked Issues Check	✅ Passed	The changes directly address the primary objective stated in issue #4983: resolving the unrecoverable parse error "Could not find Terragrunt configuration settings" and eliminating the cryptic logging artifact "Errors: %!w(...)". The code modifications in config/config_partial.go add early deprecated configuration detection, internal/discovery/discovery.go implements graceful skipping of include-only configs and fixes error formatting in logging, and internal/runner/runnerpool/controller.go corrects log output formatting. The addition of regression tests validates that deprecated syntax detection and run-all scenarios work correctly without parsing artifacts.
Out of Scope Changes Check	✅ Passed	All code changes are directly aligned with the stated PR objectives and linked issue #4983. The modifications address: improved detection of legacy fields during HCL parsing, enhanced discovery error handling with better logging (eliminating %w formatting artifacts), correct log formatting in the runner pool, and comprehensive test coverage for the new behaviors. The test fixtures and regression tests are specifically designed to validate the fixes and prevent future regressions in these areas.
Description Check	✅ Passed	The pull request description includes all required sections from the template: a substantive Description section with clear bullet points and an issue reference (Fixes #4983), a completed TODOs checklist with items marked as done, and Release Notes and Migration Guide sections. While the Release Notes and Migration Guide contain placeholder text rather than fully detailed content, the description provides sufficient context about the changes and demonstrates the fix through before/after screenshots. The description is mostly complete with all major structural elements present.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch 4983-parse-error

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📜 Recent review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b6c6911 and cdc4e56.

📒 Files selected for processing (1)

• internal/discovery/discovery.go (5 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• internal/discovery/discovery.go

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[yhakbar]

This is odd to me. Why don't we just nil check later?