core(cli): accept flags from path

[patrickhulce]

Summary
In order to easily accept an LH settings object over in Lighthouse CI, we need a way to easily passthrough the object. This can be done with config today but you miss out on some nice features like being able to use --budgets-path, set the --output-path, etc.

This is a low-cost way to enable consumers of the LH CLI that run in a child process programmatic access to all our CLI flags without manually (and error-pronely) constructing an argument list.

[brendankenny]

neat

[brendankenny]

can you add a description specifying that other flags will override this one? (e.g. --throttling-method=provided on the command line will override "throttling-method": "devtools" in the settings file)

[brendankenny]

also, bikeshed time: should we call it something like cli-flags-path?

[brendankenny]

also, copy over to readme :)

[patrickhulce]

can you add a description specifying that other flags will override this one?

Yes, test added too! 👍

cli-flags-path

WFM!

also, copy over to readme

This feels close to an autopopulate script too if only we made changes more frequently 🤔

[brendankenny]

This feels close to an autopopulate script too if only we made changes more frequently 🤔

definitely, and it's a little silly we have it at all, but I know I've at least found it useful in the past, so.... 🤷‍♀

[paulirish]

wfm! 👍

[brendankenny]

LGTM

I don't entirely understand how you're going to use it (is CI going to replicate some of the stuff in bin.js e.g. for bundget-path and output-path? or is it going to be calling the CLI?), but it makes sense on its own, too, so SG :)

[patrickhulce]

I don't entirely understand how you're going to use it

Basically I want to use the existing logic for outputPath so I can't use the node integration, but I also want to pass a budget directly as JSON, which I can't really do from CLI flags :)

The solution that works today is a blend of config and flags but it's just so much cleaner to have it all co-located