cmd/tetra: add explain command for standalone CRD documentation

[AritraDey-Dev]

Fixes #2073

Description

See commit.

Changelog

new(cmd/tetra): add explain command for standalone CRD documentation

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[FedeDP]

Left a suggestion to improve the implementation.

[FedeDP]

Can you squash the commits into a single one?

[FedeDP]

Question about this one: what are we supporting by doing so (considering we are leaving out the string between "[" and "]")?

Should we expand this a little bit to support eg:

./tetra explain tracingpolicy[spec][uprobes]

[AritraDey-Dev]

Yes, this is a limitation and needs to be expanded. It requires a separate function to handle it. I will implement this in the next commit.

[AritraDey-Dev]

Implemented!

./tetra explain tracingpolicy[spec][uprobes]
KIND:     TracingPolicy
VERSION:  v1alpha1

FIELD:    uprobes <[]object>

DESCRIPTION:
     A list of uprobe specs.

FIELDS:
   addrs        <[]integer>
     List of the traced addresses

   args <[]object>
     A list of function arguments to include in the trace output.

   btfPath      <string>
     path for a BTF file for the traced binary

   data <[]object>
     A list of data to include in the trace output.

   message      <string>
     A short message of 256 characters max that will be included
in the event output to inform users what is going on.

   offsets      <[]integer>
     List of the traced offsets

   path <string> -required-
     Name of the traced binary

   refCtrOffsets        <[]integer>
     List of the traced ref_ctr_offsets

   return       <boolean>
     Indicates whether to collect return value of the traced function.

   returnArg    <object>
     A return argument to include in the trace output.

   selectors    <[]object>
     Selectors to apply before producing trace output

   symbols      <[]string>
     List of the traced symbols

   tags <[]string>
     Tags to categorize the event, will be include in the event output.
Maximum of 16 Tags are supported.

[FedeDP]

🚀

[FedeDP]

This is quite ready; left some comments :)
Btw let me take one moment and thank you for this! Not only does this close a requested feature from long ago, but i think it is really useful! 🚀

[FedeDP]

Wdyt if we drop supportedResources in favor of using client.AllCRDs?
I got a patch that should work fine. At that point we basically have no custom code in explain.go :)
explain.patch

We also use aliases (ie: short names) from the crds.

Example:

$ ./tetra explain --list
NAME                     SHORTNAMES
TracingPolicy            tgtp
TracingPolicyNamespaced  tgtpn
PodInfo                  tgpi

And

$ ./tetra explain tracingpolicies
Error: unsupported resource: tracingpolicies (supported resources: PodInfo, TracingPolicy, TracingPolicyNamespaced, tgpi, tgtp, tgtpn)

And:

$ ./tetra explain tracingpolicy
KIND:     TracingPolicy
VERSION:  v1alpha1

DESCRIPTION:


FIELDS:
   apiVersion	<string>
     APIVersion defines the versioned schema of this representation of an object.

   kind	<string>
     Kind is a string value representing the REST resource this object represents.

   metadata	<object> -required-

   spec	<object> -required-
     Tracing policy specification.

[AritraDey-Dev]

Got it — usingclient.AllCRDsmakes sense and removes the need for maintaining supportedResources.
I’ll update the PR accordingly.

[FedeDP]

Thanks! And sorry for the scattered review :) I am going through it piece by piece!
After this we will be finally over! Thanks for your patience!

[FedeDP]

LGTM! Thank you very much!