Background
I am designing a CLI for a container build tool I am making. It uses Gentoo’s Portage behind the scenes
Question
I want to give the user the ability to specify a custom package repository. The repository must have a name, URI and sync type.
custom_repo: {
uri: 'https://...',
name: 'custom',
sync_type: 'git',
}
How do I have the user represent this in the CLI? keep in mind, this is not the main input and is optional.
One way is to make this only provide-able via a config file using JSON or another structured data representation. But I want to see if theres a good way to do it in the CLI
What I am thinking of:
command --custom-repo uri='https://...',name=custom,sync_type=git --custom-repo ... [main input]
Is this the best way of doing this?
Just pass in the name of a json file as a CLI input (or default the name and act on it if present or use it if indicated [e.g. /U == use json.config]).
Yea, as a user I’d second the use of a configuration file - that approach tends to be much more convenient to use… especially since most users won’t often change these values.
I will definitely make that an option, but I would still want it to be invokable via CLI only if the user chooses. It makes scripting easier sometimes.
How about a command-line flag to name an input file, but also process input as JSON, so someone can pipe it to your command or hand-write it if they’re crazy?
perhaps also useful in this case to document the shortcut of
<(echo ‘{…}’)since not many people know about it, and it makes your tool work with things specified entirely on the command line rather than temp files
alternatively —config-file and —config-json or similar
making and cleaning up temp files when writing scripts is just such a massive PITA
If the json payload is small with finite keys you can support separate args for those keys. If you really need arbitrary json what you have described is fairly reasonable as a shorthand, similar to AWS CLI shorthand.
Honestly passing optional/advanced args as json via CLI isn’t usually too bad since you can quote it with single quotes.
For something like that i’d take a parameter like this (repeated as necessary):
--custom-repo==+for example:
--custom-repo=custom=git+https://github.com/matcha/customcommand --git-url https://... --alias myalias --svn-url http://... --alias mysvnaliasYou may process it as a stack.
When reading within the program from stdin I recommend a state machine.
What language? This would be simple with Python’s argparse or Go’s pflag.
I’m having the same problem. this kind of nested argument is quite annoying to program in e.g. argp. i am even thinking of using a minimal forth like parser to do this.
Ask the user to customize a preset.json?
That is certainly one solution and I plan to make that an option. But I’d still like to make the program invokable without having to write a file.
You could read json from standard input. Ex:
echo << EOF | command --read-stdin Some JSON EOFcommand --custom-repo-uri https://foo.com --custom-repo-name repo_name --custom-repo-sync-type gitThere could be multiple custom repos, so it would be difficult to know which uri goes with which repo name, and so on.
