Display an error/warning when mutually exclusive flags are set in scope

[seanvaleo]

These combinations of flags should probably throw a user error or warning message:

(with scope run):

• --cribldest && --eventdest
• --cribldest && --metricsdest
• --userconfig && (--metricsdest || --eventsdest || --cribldest || --loglevel ....etc)
• --passthrough && [anything else]

Considerations
Currently scope proceeds for all of these combinations, silently overriding or bypassing mutually exclusive flags. Should we warn and let scope proceed anyway? Should we throw an error and have the user fix their arguments?

Related: spf13/cobra#1216

[seanvaleo]

It makes more sense to notify the user of error, to avoid unexpected results; and to avoid discovering a bug.

In cobra there is an option to create flag sets but this appears to have limitations. It is easier to write conditions that check for invalid combinations, and return an error to the user.

We should:

• Create an arg matrix at the top of command files
• Create conditions that return an error with bad argument combinations

[seanvaleo]

• scope attach
• scope completion
• scope dash
• scope events
• scope flows
• scope help
• scope history
• scope metrics
• scope prune
• scope ps
• scope run

[seanvaleo]

QA INSTRUCTIONS

Part 1
Do:

docker run --rm -it cribl/scope:<VERSION_ID>
apt update
apt install curl -y
scope curl wttr.in
scope events --follow --sort _time
scope events --match http --all
scope flows --in --out
# etc...

Expect:
Nonsensical argument combinations should not be allowed and should exit and throw a user help message.

[jrcheli]

I found one small thing during the bugathon of this with 1.0.2-rc0. I'll write it up in #839. In all other ways, this looks great!