x/exp/cmd/gorelease: support -json and -f flags

[jayconrod]

gorelease prints its findings to stdout as plain text. The report format may change over time and can't be safely read by tools.

gorelease should accept -json and -f flags, which should produce either JSON or text/template output.

[gopherbot]

Change https://golang.org/cl/280772 mentions this issue: x/exp/cmd/gorelease: support -json flag

[jeanbza]

I've started looking into the json side of things in https://go-review.googlesource.com/c/exp/+/280772. I think it's approachable, but will require adding JSON methods and implementing json.Marshaler in various places.

Some questions though:

• Are we intending on still panic'ing/log.Exit'ing normally, or should those be json format too?
• I'm fairly new to text/template. Does it start by defining the data structure (same struct as JSON struct?) and then basically template.New(...).Parse(-f flag)?

In general seems like the complexity here is to define a data structure that makes sense of all the outputs, and giving it .Text/.Template/.JSON methods, rather than printing to buffers in various places. Does that seem right?

[jayconrod]

I'd rather hold off on -json and -f until basically everything else is done. These flags will let other programs consume gorelease output, but the output isn't stable yet, so it wouldn't be safe to use these flags.

About implementation, we'll need to change or at least export the field names in the report type so that encoding/json and text/template can see them via reflection. Hopefully, we won't need to implement json.Marshaler or define any special methods.

[jeanbza]

I'd rather hold off on -json and -f until basically everything else is done.

SGTM

About implementation, we'll need to change or at least export the field names in the report type so that encoding/json and text/template can see them via reflection.

Aha, this makes more sense. Thanks.

[gopherbot]

Change https://golang.org/cl/333371 mentions this issue: cmd/gorelease: support -json and -f flags