Fixing the cluster spec output formatting issue

[viggy28]

To address #723.

[sgotti]

@viggy28 Thanks for your PR! Can you rework the commit message and description with something more descriptive like:

stolonctl: don't show null clusterspec options

make the clusterspec struct fields tagged as json `omitempty` so they will be omitted when null marshaled.
This won't have any side effect on clusterdata writing but will make stolonctl don't show them.

[viggy28]

Hi @sgotti, thanks for looking. Updated it.

[sgotti]

@viggy28 Thinking and testing this PR I noticed that it will break the stolonctl spec --defaults output hiding some defaults values.

One possible solution will require the creation (in stolonctl_spec.go), of two different cluster spec structs (identical to the original cluster spec, one with all json tags with omitempty and one without omitempty) that could be converted from the original clusterspec so their marshalling will work for both cases (this will also help detecting when we forgot to add new fields to all the structs at compilation time).

[viggy28]

Thanks @sgotti. Updated the PR. Let me know if that works.

[sgotti]

There's the need of two different cluster spec structs identical to the original cluster spec:

• one with all json tags with omitempty for normal output
• one with all json tags without omitempty for --default output

[sgotti]

Just remove all the fields comments.

[viggy28]

updated.

[sgotti]

One possible solution will require the creation (in stolonctl_spec.go), of two different cluster spec structs (identical to the original cluster spec, one with all json tags with omitempty and one without omitempty) that could be converted from the original clusterspec so their marshalling will work for both cases (this will also help detecting when we forgot to add new fields to all the structs at compilation time).

@viggy28 Sorry if I wasn't clear but I meant to use two new structs inside stolonctl/cmd/spec.go, take a look at this compare:

https://github.com/sorintlab/stolon/compare/master...sgotti:stolonctl_spec_improve_output?expand=1

[sgotti]

@viggy28 Thanks for your PR, I created a PR #736 with an updated implementation.