Make stage-snap jobs more smart about pushing metadata

[anonymouse64]

Currently, all of the snap's that are released from the jenkins stage-snap jobs also have a step to push the metadata for the snap:

ci-management/shell/edgexfoundry-snapcraft.sh

Lines 81 to 82 in 0bb57b7

	# Also force an update of the meta-data
	snapcraft push-metadata "$SNAP_NAME"*.snap --force

This is less than ideal because when we start having multiple git branches building stage-snap jobs concurrently, if the metadata gets out of sync the metadata on the store page will flip between the two jobs as the stage-snap jobs for each branch runs. What we did for edgex-go (and thus the edgexfoundry snap) is just to ensure that the metadata such as the title, description, license, etc. always matches across the git branches so that there is no visible changes, however this is hacky and subject to be forgotten as maintainers change, etc.

Instead what would be ideal is to have the stage-snap job check if it needs to push metadata by checking 2 conditions:

• The stage-snap job is building on the master branch (we probably only want to pull metadata from the master branch)
• The metadata in the snap file that was just built by the stage-snap job doesn't match what is already in the store. This could be done with the snap store's REST API, but would be a little bit finicky I think.

Note that this would probably just be another step in a potential snap job jenkins pipeline

[jamesrgregg]

@tonyespy perhaps you could take a look at this issue in our icebox and let us know if this is still relevant and something we should consider for Hanoi scope. Thank you.

[tonyespy]

@jamesrgregg yes, I think this should be considered for Hanoi. The proposed changes are fairly simple. At minimum, we just restrict the metadata push to releases from master. I'm not sure it's worth doing the additional optimization (i.e. diff store metadata against local metadata, and only push if different) though.