A custom CLI app built with Atmos

Build a CLI app that reads a JSON service manifest and reports replica totals. The program is written in the Atmos Automation Language, a Python-like language based on Starlark. Atmos supplies the interpreter, file access, JSON decoding, and terminal output. Run it with atmos ./summarize.star services.json, or use the #!/usr/bin/env atmos shebang to execute it directly. This example needs only Atmos.

From this directory, with Atmos on PATH:

./summarize.star services.json

The app reports each service's replica count with ui.info and highlights the total of five replicas with ui.success. Its argument comes from ctx.args; fs.read_file and json.decode are built in.

On Windows, or without the executable bit, run atmos ./summarize.star services.json. Input paths are relative to your working directory.

For a script with a declared command-line interface, run:

./capacity.star api --replicas 3
./capacity.star --help

capacity.star declares a required service argument and an integer flag with a default. Atmos parses the inputs, prints help, and runs validation before calling main(args, flags). The callback reads the parsed dictionaries directly.

This custom CLI app declares its own interface with cli.command inside the script. To add a project-specific subcommand such as atmos capacity, define it in atmos.yaml instead; see the custom command example.

See the standalone script reference.