image-based gadgets: Implement support for toppers gadgets

[mauriciovasquezbernal]

Issue Tracker

• [x] top blockio #2989
• [ ] top ebpf #3443

See more details on https://github.com/inspektor-gadget/inspektor-gadget/issues/1924#issuecomment-2127209677

[mauriciovasquezbernal]

Fixed by https://github.com/inspektor-gadget/inspektor-gadget/pull/2132.

[blanquicet]

Reopening as this support was removed after https://github.com/inspektor-gadget/inspektor-gadget/pull/2512.

[blanquicet]

TODOs before removing IG_EXPERIMENTAL flag:

• [x] Prepare snapshotters to easily collect the outcome of all iterators so that we can emit the whole output of a snapshotter in one single batch. Currently, we are sending one entry at a time:

  • 2637

• [x] Support sending arrays of data in a single batch and apply it to snapshotters:
  • https://github.com/inspektor-gadget/inspektor-gadget/pull/2709
• [x] Create new operator for sorting:
  • https://github.com/inspektor-gadget/inspektor-gadget/pull/2844
• [x] Support mapIters:
  • https://github.com/inspektor-gadget/inspektor-gadget/pull/3182
• [x] Create new operator that combines output from all nodes on client side:
  • https://github.com/inspektor-gadget/inspektor-gadget/pull/3068
• [x] Create toppers using mapIters:
  • [x] top_file: https://github.com/inspektor-gadget/inspektor-gadget/pull/3207
  • [x] top_tcp: #3259

TODOs that can be managed after removing IG_EXPERIMENTAL flag:

• [x] Create new cutter operator (Or maybe inside the sorter operator) to be able to specify a fixed amount of entries per update on toppers (basically implement --max-rows flag on client and server side):
  • https://github.com/inspektor-gadget/inspektor-gadget/pull/3327
• [ ] Create top_ebpf using mapIters #3443
• [x] top_block-io: #3273

This TODO list is the conclusion of discussion in Slack. Feel free to start working on any of these tasks but please write it here to avoid duplicated work.

[mauriciovasquezbernal]

I don't think it was fixed by #2844, reopening.