Follow CLI args standards in Falco

[incertum]

Proposing to follow common and standard Program Argument Syntax Conventions for Falco's CLI options, for example see this resource. For example -pk and similar options seem to fall outside of these conventions.

[GLVSKiriti]

@Andreagit97 @incertum I am interested in this issue!
Can I work on this?

[Andreagit97]

Not clear to me what was the plan @incertum had in mind when she opened this issue, so I'll let her answer here.
My 2 cents, this issue seems related to possible breaking changes in the Falco UX, maybe something that we want to tackle for Falco 1.0.0, not sure this is a "good first issue" but let's see what others think about that

[incertum]

Goal is to correct the -pc, -pk or -pcontainer, -pkubernetes flags that do not conform to standard CLI practices. Usually -pc implies a combination of -p and -c.

https://falco.org/docs/outputs/formatting/

falco/userspace/falco/app/options.cpp

Line 187 in 99781f7

("p,print", "Print (or replace) additional information in the rule's output.\nUse -pc or -pcontainer to append container details.\nUse -pk or -pkubernetes to add both container and Kubernetes details.\nIf using gVisor, choose -pcg or -pkg variants (or -pcontainer-gvisor and -pkubernetes-gvisor, respectively).\nIf a rule's output contains %container.info, it will be replaced with the corresponding details. Otherwise, these details will be directly appended to the rule's output.\nAlternatively, use -p <output_format> for a custom format. In this case, the given <output_format> will be appended to the rule's output without any replacement.", cxxopts::value(print_additional), "<output_format>")

I would propose them being:

• -pc -> --print-container and --print-container-gvisor or similar
• -pk -> --print-kubernetes and --print-kubernetes-gvisor or similar

Suggesting to sync with @leogr.

[leogr]

Usually -pc implies a combination of -p and -c.

This is the main issue, likely.

If we follow POSIX's recommendation:

Multiple options may follow a hyphen delimiter in a single token if the options do not take arguments. Thus, ‘-abc’ is equivalent to ‘-a -b -c’.

So, -pc is not ok.

But:

An option and its argument may or may not appear as separate tokens. (In other words, the whitespace separating them is optional.) Thus, -o foo and -ofoo are equivalent.

So -pcontainer is equivalent to -p container and it would be ok (and it is what's happening here).

My recommendation is to reaudit all flags, and try to make them consistent with POSIX.
The cobra project may be a source of inspiration. Also, if we follow Cobra/posix recommendations, we will have consistency across all our other tools (which are implemented in Go).

Let's dig deeper into this once we have found some time.

[incertum]

Agreed @leogr let's investigate more. It's something valuable for Falco 1.x.