Implement InvalidDefinitionDescription Rule Check

[daghack]

Description

If a comment is right before FROM or ARG it could be considered as part of the command and we could request specific format. If user doesn’t care and comment isn’t specifically for the command they could add a empty line.

Output Message

Description comment for stage () is invalid. Should be of the format <STAGE NAME> <DESCRIPTION>. If this is not intended to be a description comment, add an empty line/comment between them
Description comment for ARG () is invalid. Should be of the format <ARG NAME> <DESCRIPTION>. If this is not intended to be a description comment, add an empty line/comment between them.

Reason

Outline/targets command can parse comments to show text descriptions. But this only works if the comment is in specific format.

Example

Bad - description doesn’t start with stage/arg name

# This is where we do all the testing
FROM busybox AS test
# Version name
ARG VERSION
...

Bad - typo in stage/arg description comment

# tests this is where we do all the testing
FROM busybox AS test
# VERISION image version to use
ARG VERSION
...

Good - Well defined comment for

# test do all the testing
FROM busybox AS test
# VERSION image version to use
ARG VERSION
...

Good - Comments, but not a description comments

# tests this is where we do all the testing

FROM busybox AS test
#
# Test arguments
#
ARG VERSION
...