snap commands need a machine readable output format

[Charles Butler]

for a good while, I've been using snaps with juju charms. One of the pain points has been the lack of machine readable output for information being emitted from commands like:

snap list
snap info

Instead of getting json/yaml everything appears to be centered around human interaction with smart output formatting. Which is great until a change happens when you're attempting to capture smart output and parse it.

Take the example of the etcd snap version parser which broke this morning:

https://github.com/juju-solutions/layer-etcd/commit/d16319981b4d296095657370a99fab4a7aac4de9

We knew walking into this that there was a good chance our scraping would break if the output changed at all using things like spaces to split output. Our fear was realized.

This can be easily mitigated by providing machine friendly output formats. I would prefer JSON as it's a more dense, and flexible format than YAML, but either would suffice for situations where we're driving snapd and need to surface information from the system.

[George Kraft (cynerva)]

I'd like to see machine readable output as well. We're building automation that needs to do validation around snap versions and I'm concerned the output of `snap list` will change in unpredictable ways.

[Zygmunt Krynicki (zyga)]

Can you use the REST API instead of running the CLI and parsing the output?

[Launchpad Janitor (janitor)]

[Expired for snapd because there has been no activity for 60 days.]