Introduce --debug and --verbose as global options

[rhuss]

In what area(s)?

Describe the feature:

Debugging and verbose output should be treated in a consistent way over all commands. Currently, we have

• kn plugin list --verbose as in refactor(plugins): Improved and simplified verifier and plugin list #313 for printing out plugin configuration
• kn service describe --details as in feature(service describe): Output of service details #252 for showing additional service information
• --log-http as a global option to track HTTP API communication coming in with Add --log-http option #326

As there are supposed to be more such output modifying flags coming in over time, I suggest to use --debug and --verbose with categories to fine tune this:

• Adding --debug for very low-level information. Only useful for developer of kn itself
• Adding a --verbose option for increasing the detail level of the information presented. Examples are
  • kn service describe --verbose to add more details to a service (like the image digests, or all env vars/annotations/labels)
  • kn plugin list --verbose to also print the plugin directories where plugins are looked up
  • kn service create --debug to print also the HTTP headers

In order to tune debug and verbose output, I'd suggest to introduce categories:

• --debug --> all debug info
• --debug=all --> all debug info
• --debug=http --> only http related debugging
• --verbose --> all verbose output
• --verbose=config --> config related information, too
• --verbose=config,details --> config information and details (made up here to show how to combine categories)

This suggestion would introduce exactly two options, --debug and --verbose (with the possible values shown in the help page). The alternative would be to have an extra option for every category like in --log-http, but this would blow up the help pages and UX surface considerably over time.

[rhuss]

Should be tackled together with #182 IMO

[github-actions]

This issue is stale because it has been open for 90 days with no
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[rhuss]

/remove-lifecycle stale

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[dsimansk]

/remove-lifecycle stale

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[rhuss]

/remove-lifecycle stale

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[rhuss]

/remove-lifecycle stale

[rhuss]

Related to this issue

• Add a -q/quiet option #182 -- --quiet is kind of the opposite of --verbose
• --log-http shouldn't write to stderr #390 -- --log-http should be included as part of --debug=http