The `camel-case-properties` rule appears flaky

[LasseHels]

Hey there!

First of all: thanks for making this awesome tool.

I am having a bit of an issue with the camel-case-properties rule. Our specification follows the camelCase convention, but we have a couple fields that must be snake_case because of a downstream constraint.

One of the field causes the linter to consistently fail. I added this to vacuum's ignore file which solved the issue:

camel-case-properties:
  - $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

However, it seems one of the other fields causes vacuum to rarely fail:

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended


 > api/openapi.yml
 ----------------------------------------------------------------------------------------------------------

api/openapi.yml:983:13  ▲     property `hedwig_scope` is `snake_case` not `camelCase`
$.components.schemas['ServiceLevelObjectiveAlertV1'].properties['ticket'].allOf[0][0].properties['labels'].properties['hedwig_scope']
rule: camel-case-properties  category: Schemas


 category              ✗ errors      ▲ warnings    ● info
 ────────────────────  ────────────  ────────────  ────────────────────────────────────────────────────────
 Schemas               0             1             0
 ────────────────────  ────────────  ────────────  ────────────────────────────────────────────────────────
 total                 0             1             0

 rule                                      violations    quality impact
 ────────────────────────────────────────  ────────────  ──────────────────────────────────────────────────
 camel-case-properties                     1             ██████████████████████████████████████████████████
 ────────────────────────────────────────  ────────────  ──────────────────────────────────────────────────
 total                                     1

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 99/100 [A+]                                                                             │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ▲ Passed, but with 1 warnings and 0 informs.
 │

 use --debug if you want to enable developer logging

make: *** [lint-openapi] Error 1
➜  redacted git:(main) make lint-openapi
vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

 ██╗   ██╗ █████╗  ██████╗██╗   ██╗██╗   ██╗███╗   ███╗ 《《《─═─═── ·* · ˙*
 ██║   ██║██╔══██╗██╔════╝██║   ██║██║   ██║████╗ ████║《《《──═─═──· ··* ˙˙
 ██║   ██║███████║██║     ██║   ██║██║   ██║██╔████╔██║《《《───═─═─··· ˙˙ ˙
 ╚██╗ ██╔╝██╔══██║██║     ██║   ██║██║   ██║██║╚██╔╝██║《《──═─═──·* ·· ˙˙
  ╚████╔╝ ██║  ██║╚██████╗╚██████╔╝╚██████╔╝██║ ╚═╝ ██║ 《《─═─═──* · · ˙
   ╚═══╝  ╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝ ╚═╝     ╚═╝ 《───═─═─· ··* ˙˙ ˙

 version: 0.20.5 | compiled: Thu, 11 Dec 2025 00:15:56 UTC
 https://quobix.com/vacuum/ | https://github.com/daveshanley/vacuum

 Using ignore file 'redacted/vacuum-ignore.yml'
 ignored items:
 └─ camel-case-properties: $.components.schemas['ServiceLevelObjectiveAlertSeverityV1'].properties['labels'].properties['hedwig_scope']

 using ruleset 'vacuum-ruleset.yml' (containing 50 rules)
 vacuuming file './api/openapi.yml' against 50 rules: https://quobix.com/vacuum/rulesets/recommended

 --> use the <dashboard> command to be able to navigate results interactively <--

┌─────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                                                                         │
│  Quality Score: 100/100 [A+]                                                                            │
│                                                                                                         │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────┘

 │
 │ ✓ A perfect score! Like Mary Poppins, practically perfect in every way. Incredible, well done!
 │

 use --debug if you want to enable developer logging

make lint-openapi is this command:

vacuum lint -r vacuum-ruleset.yml ./api/openapi.yml --fail-severity=info --details --ignore-file=vacuum-ignore.yml --no-clip

This is the vacuum-ruleset.yml file:

---
extends:
  - [spectral:oas, recommended]
rules:
  oas3-missing-example: false
  component-description: false
  operation-description: false
  no-unnecessary-combinator: false

It is curious to me that the field in the ignore file causes vacuum to consistently fail, but that the other field does not have the same effect. I can't share our entire OpenAPI specification, but I may be able to share parts of it if there's something you need to know about it in order to debug.

I realise I can update my ignore file with the field that rarely fails, but I am curious to understand why it rarely fails. My expecation would be that it either always fails or always succeeds.

[daveshanley]

investigating this for you.

[daveshanley]

Addressed in v0.21

The reason is that there has been some non-deterministic behavior in libopenapi that was unresolved. It operated across a number of async issues that needed bringing together. One of them being a 'first past the post' problem.

I added a few differnt solutions to libopenapi, including canonical path building, sequencing, the use of singleflight and a few other things. However it has resolved the issue of flakinness.