yamlfmt

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

Goals

• 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

Maintainers

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

Installation

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

Usage

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.)

Configuration

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

Include/Exclude

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

Formatter

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
  indentation: 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.

Flags

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)