Fix Agents.UnmarshalYAML to reject unknown fields#1684
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dgageot merged 1 commit intodocker:mainfrom Feb 10, 2026
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Agents.UnmarshalYAML re-marshals each agent value to bytes and calls yaml.Unmarshal to parse it into AgentConfig. This plain Unmarshal call does not enforce strict field validation, so unknown fields like 'instructions' (instead of 'instruction') are silently ignored — even though Parse() uses yaml.Strict() at the top level. Switch to yaml.UnmarshalWithOptions with DisallowUnknownField so that the strictness is propagated into agent blocks. Fixes docker#1683 Assisted-By: cagent
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Review Summary
✅ No issues found
The changes correctly implement strict YAML field validation by replacing yaml.Unmarshal() with yaml.UnmarshalWithOptions() using the yaml.DisallowUnknownField() option. This will properly reject typos like "instructions" instead of silently ignoring them.
Changes reviewed:
- ✅
pkg/config/latest/types.go: Correct implementation with proper error handling - ✅
pkg/config/v4/types.go: Correct implementation with proper error handling - ✅ Tests added to validate both rejection of unknown fields and acceptance of valid configs
The implementation is minimal, focused, and addresses the issue described in #1683.
dgageot
approved these changes
Feb 10, 2026
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Problem
latest.Parse()andv4.Parse()callyaml.UnmarshalWithOptions(data, &cfg, yaml.Strict())to reject unknown fields. However,Agents.UnmarshalYAMLre-marshals each agent value to bytes and calls plainyaml.Unmarshal, which does not enforce strict field validation. Unknown fields in agent blocks are silently ignored.For example, writing
instructions(plural) instead of the correctinstruction(singular) produces no error, but the instruction is completely lost — the agent runs with no instructions at all.Fixes #1683
Fix
Change
yaml.Unmarshal(valueBytes, &agent)toyaml.UnmarshalWithOptions(valueBytes, &agent, yaml.DisallowUnknownField())in bothlatest/types.goandv4/types.go.Tests
Added tests to both
latest/types_test.goandv4/types_test.go:TestAgents_UnmarshalYAML_RejectsUnknownFields— verifiesinstructions(plural) is rejectedTestAgents_UnmarshalYAML_AcceptsValidConfig— verifiesinstruction(singular) still worksAll existing tests pass, including the full
TestParseExamplessuite that validates all example YAML configs.