yaml validate

1. Introduction
2. Self-Help Documentation

Introduction

The yaml-validate command-line tool validates one or more single- or multi-document YAML, JSON, and compatible files. Under its default configuration, the following output is generated:

• When there are no issues:

$ yaml-validate valid*.*

$ echo $?
0

• When there are validation errors:

$ yaml-validate invalid*.*
invalid-multidoc.json/1 is invalid due to:
  * YAML parsing error in "invalid-multidoc.json", line 3, column 1:  expected ',' or ']', but got '['
invalid-multidoc.yaml/1 is invalid due to:
  * YAML composition error in "invalid-multidoc.yaml", line 10, column 19:  found undefined alias 'alias'
invalid-singledoc.json/0 is invalid due to:
  * YAML parsing error in "invalid-singledoc.json", line 1, column 3:  expected the node content, but found '}'
invalid-singledoc.yaml/0 is invalid due to:
  * YAML syntax error in "invalid-singledoc.yaml", line 3, column 12:  mapping values are not allowed here

$ echo $?
2

For this demonstration, there were 4 deliberately invalid documents; YAML and JSON single- and multi-document files. Each of the multi-document files contained 3 documents with a deliberate error on the second of each type.

When you want the report to also list valid documents, add the --verbose flag, like so:

$ yaml-validate --verbose valid*.*
valid-multidoc.json/0 is valid.
valid-multidoc.json/1 is valid.
valid-multidoc.json/2 is valid.
valid-multidoc.yaml/0 is valid.
valid-multidoc.yaml/1 is valid.
valid-multidoc.yaml/2 is valid.
valid-singledoc.json/0 is valid.
valid-singledoc.yaml/0 is valid.

$ echo $?
0

A verbose report against all 8 valid and invalid documents would be much more noisy:

$ yaml-validate --verbose *.*
invalid-multidoc.json/0 is valid.
invalid-multidoc.json/1 is invalid due to:
  * YAML parsing error in "invalid-multidoc.json", line 3, column 1:  expected ',' or ']', but got '['
invalid-multidoc.yaml/0 is valid.
invalid-multidoc.yaml/1 is invalid due to:
  * YAML composition error in "invalid-multidoc.yaml", line 10, column 19:  found undefined alias 'alias'
invalid-singledoc.json/0 is invalid due to:
  * YAML parsing error in "invalid-singledoc.json", line 1, column 3:  expected the node content, but found '}'
invalid-singledoc.yaml/0 is invalid due to:
  * YAML syntax error in "invalid-singledoc.yaml", line 3, column 12:  mapping values are not allowed here
valid-multidoc.json/0 is valid.
valid-multidoc.json/1 is valid.
valid-multidoc.json/2 is valid.
valid-multidoc.yaml/0 is valid.
valid-multidoc.yaml/1 is valid.
valid-multidoc.yaml/2 is valid.
valid-singledoc.json/0 is valid.
valid-singledoc.yaml/0 is valid.

$ echo $?
2

Self-Help Documentation

When the --help (-h) flag is passed to yaml-validate, it generate the following documentation:

usage: yaml-validate [-h] [-V] [-S] [-d | -v | -q] [YAML_FILE [YAML_FILE ...]]

Validate YAML, JSON, and compatible files.

positional arguments:
  YAML_FILE      one or more single- or multi-document YAML/JSON/compatible
                 files to validate; omit or use - to read from STDIN

optional arguments:
  -h, --help     show this help message and exit
  -V, --version  show program's version number and exit
  -S, --nostdin  Do not implicitly read from STDIN, even when there are no -
                 pseudo-files in YAML_FILEs with a non-TTY session
  -d, --debug    output debugging details
  -v, --verbose  increase output verbosity (show valid documents)
  -q, --quiet    suppress all output except system errors

Except when suppressing all report output with --quiet|-q, validation issues
are printed to STDOUT (not STDERR). Further, the exit-state will report 0 when
there are no issues, 1 when there is an issue with the supplied command-line
arguments, or 2 when validation has failed for any document.