»fmt Command

The packer fmt Packer command is used to format HCL2 configuration files to a canonical format and style. JSON files (.json) are not modified. This command applies a subset of HCL language style conventions, along with other minor adjustments for readability.

packer fmt will display the name of the configuration file(s) that need formatting, and write any formatted changes back to the original configuration file(s).

Example usage:

Check if configuration file(s) need to be formatted, but don't write the changes.

$ packer fmt -check .

Format a configuration file, writing the changes back to the original file.

$ packer fmt my-template.json


  • -check - Checks if the input is formatted. Exit status will be 0 if all input is properly formatted and non-zero otherwise.

  • -diff - Display diffs of any formatting change

  • -write=false - Don't write formatting changes to source files (always disabled if using -check)