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Reading from Stdin

The validator can read input from stdin instead of traversing the filesystem. Use - as the search path and specify the file type with --file-types.

Basic usage​

echo '{"key": "value"}' | validator --file-types=json -
cat config.yaml | validator --file-types=yaml -

Requirements​

  • The search path must be exactly -
  • - must be the only search path — it cannot be combined with other paths
  • --file-types must specify exactly one file type
  • Input is read until EOF

Use cases​

Validate config fetched from a remote source:

curl -s https://config-service.internal/app.json | validator --file-types=json -

Validate the output of a template engine or merge tool — the processed result, not the source file:

helm template my-chart | validator --file-types=yaml -
envsubst < config.template.yaml | validator --file-types=yaml -

Behavior​

When reading from stdin:

  • The validator reads all input, parses it as the specified type, and reports pass or fail.
  • Schema validation applies if the content declares a schema (e.g., a $schema property in JSON).
  • --schema-map patterns do not apply since there is no filename to match against.
  • The reported filename in output is stdin.
  • Exit codes are the same as filesystem mode: 0 for valid, 1 for invalid.