yamlfmt

yamlfmt is an extensible command line tool or library to format yaml files.

• Create a command line yaml formatting tool that is easy to distribute (single binary)
• Make it simple to extend with new custom formatters
• Enable alternative use as a library, providing a foundation for users to create a tool that meets specific needs

This tool is not yet officially supported by Google. It is currenlty maintained solely by @braydonk.

To download the yamlfmt command, you can download the desired binary from releases or install the module directly:

go install github.com/google/yamlfmt/cmd/yamlfmt@latest

By default, the tool will recursively find all files that match the glob path **/*.{yaml,yml} extension and attempt to format them with the basic formatter. To run the tool with all default settings, simply run the command with no arguments:

yamlfmt

You can also run the command with paths to each individual file, or with glob paths:

yamlfmt x.yaml y.yaml config/**/*.yaml

(NOTE: Glob paths are implemented using the doublestar package, which is far more flexible than Go's glob implementation. See the doublestar docs for more details.)

The tool can be configured with a .yamlfmt configuration file in the working directory. The configuration is specified in yaml.

If you would like to have a consistent configuration for include and exclude paths, you can also use a configuration file. The tool will attempt to read a configuration file named .yamlfmt in the directory the tool is run on. In it, you can configure paths to include and exclude, for example:

include:
  - config/**/*.{yaml,yml}
exclude:
  - excluded/**/*.yaml

In your .yamlfmt file you can also specify configuration for the formatter if that formatter supports it. To change the indentation level of the basic formatter for example:

formatter:
  type: basic
  indent: 4

If the type is not specified, the default formatter will be used. In the tool included in this repo, the default is the basic formatter.

The CLI supports 3 operation modes:

• Format (default, no flags)
  • Format and write the matched files
• Dry run (-dry flag)
  • Format the matched files and output the diff to stdout
• Lint (-lint flag)
  • Format the matched files and output the diff to stdout, exits with status 1 if there are any differences
• Stdin (-in flag)
  • Format the yaml data from stdin and output the result to stdout

(NOTE: If providing paths as command line arguments, the flags must be specified before any paths)