✨ Adds generator for JSON version of the validator spec

[fstanis]

This makes it easier to consume by scripts to e.g. pull the list of all tags allowed by a specific format or generate autocomplete definitions for playground.amp.dev.

[danielrozenberg]

Looks like the import of json_format fails on Travis - maybe one of @Gregable @honeybadgerdontcare @rsimha know how to add it?

It's also missing from the check on this line:

amphtml/validator/build.py

Line 84 in 43b0729

for m in ['descriptor', 'text_format']:

[rsimha]

It's also missing from the check on this line:

amphtml/validator/build.py

Line 84 in 43b0729

for m in ['descriptor', 'text_format']:

Good catch.

I think this section in validator/README.md needs to be updated, and the required package needs to be added to this list for Travis runs:

amphtml/.travis.yml

Lines 23 to 31 in df19f09

	addons:
	apt:
	packages:
	# Use unbuffer (from expect-dev) for log coloring (github.com/travis-ci/travis-ci/issues/7967)
	- expect-dev
	- google-cloud-sdk
	- openssl
	- protobuf-compiler
	- python-protobuf

[fstanis]

Any idea which package specifically we need to add? I was 99% sure it's part of python-protobuf.

[rsimha]

Any idea which package specifically we need to add? I was 99% sure it's part of python-protobuf.

According to https://stackoverflow.com/questions/2456664/google-protobuf-in-linux, it's in protobuf-compiler. But we already install that package, so I'm not sure where it really is.

Over to @honeybadgerdontcare @Gregable 😃

[Gregable]

I have no idea, sorry.

[fstanis]

After digging a little bit, it seems that the last published version of python-protobuf for xenial is the (now ancient) 2.6.1-1.3 which had no JSON support.

pip install protobuf gets the latest version, so I hope this will work with Travis...

[fstanis]

Well, that seems to have worked. Also updated README and build.py message.