linter error

[jakoch]

Input

Given this workflow.yml

name: Lint

on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Advanded Linting Devices Inc.
        run: |
          sudo apt-get update
          sudo apt-get install -y advanced-linting-device

      - name: Set locale
        run: |
          export LC_ALL=C.UTF-8

        - name: COMMON → Lint line endings (show files with DOS LE and EOL errors)
          run: |
            find -name '*.*' -print0 | xargs -0 dos2unix -ice

Expected Output

• Identation error on line 22

Actual Output

• could not parse as YAML: yaml: line 16: did not find expected key [syntax-check]

Analysis

The wrong indention in the last step causes the linter to assume an invalid could not parse as YAML: yaml: line 16: did not find expected key [syntax-check] error.

References

• Playground Error

[riva-infinex]

For fellow Googlers:

THis cryptic error also happens when using brackets: [foo] which actionlint doesn't like at all (even though GA works)

[muzimuzhi]

@jakoch As a comparison, the pyyaml-based YAML parser throws two errors on your YAML example (link):

ERROR:

while parsing a block mapping
  in "<unicode string>", line 17, column 9:
          - name: Set locale
            ^
expected <block end>, but found '-'
  in "<unicode string>", line 21, column 9:
            - name: COMMON → Lint line endin ... 
            ^

@riva-infinex Could you provide a concrete example?

[riva-infinex]

@muzimuzhi cryptic error https://rhysd.github.io/actionlint/#eJxTVshIzcnJV+TiykvMTbVSiHbLz49VSEos4gIAZuYHww==

[muzimuzhi]

@riva-infinex name: [Foo] bar is an invalid YAML. https://yaml-online-parser.appspot.com/?yaml=name%3A+%5BFoo%5D+bar&type=json

[...] represents an inline sequence (technically called "flow sequence"), which cannot be followed by a string on the same line. To specify a string which starts with [, quoting the whole string is a common workaround.

# single-quoted
name: '[Foo] bar'
# double-quoted
name2: "[Foo] bar"

https://yaml-online-parser.appspot.com/?yaml=name%3A+%27%5BFoo%5D+bar%27%0Aname2%3A+%22%5BFoo%5D+bar%22&type=json

Update: If the GitHub Actions accepts such YAML snippet, then it's YAML parser might not be strict enough.

[riva-infinex]

@muzimuzhi I completely agree! My comment is about the cryptic error message:

1. (playground above) it complains about line 2 when the error is on line 3
2. the message "did no find expected key" doesn't mention anything about brackets or flow sequences

[muzimuzhi]

@riva-infinex The cryptic error message "did not find expected key" was provided by the YAML parser gopkg.in/yaml.v3 v3.0.1 used by actionlint, so it's an upstream issue. See reproduction steps at the end.

https://github.com/rhysd/actionlint/blob/2ab3a12c7848f6c15faca9a92612ef4261d0e370/go.mod#L16

The shifted line number seems to be caused by actionlint.

Reproduction of "did not find expected key" error message:

• open https://pkg.go.dev/gopkg.in/[email protected]#example-Unmarshal-Embedded
• Edit the embedded example

   var data = `
  -a: a string x from struct A
  +a: [Foo] bar
   b: a string x from struct B
   `
  

• Click the lower-right "Run" button, wait, and get the error message

  2009/11/10 23:00:00 cannot unmarshal data: yaml: line 1: did not find expected key
  

Unfortunately, the source repo of the Go package gopkg.in/yaml has been archived on Apr 2, 2025. See https://github.com/go-yaml/yaml.

[jakoch]

Thank you for taking the time to analyze this. I just checked the dependencies of yq and noticed it includes goccy/go-yaml. This might serve as a potential replacement package.