Current situation

Containerized gadgets have a ebpf module but currently don't yet contain code in userspace to handle events.

Impact

Some gadgets lose features after they're converted from the build-in gadget to a containerized gadget.

Example: the dns gadget has a "NAME" column with a domain name with dots:

$ sudo ig trace dns -c test-trace-dns
QR TYPE      QTYPE      NAME
Q  OUTGOING  A          inspektor-gadget.io.

This string is built up from userspace. The ebpf program only sends the encoded name from the DNS packet. The containerized dns gadget does not have this string with dots.

Ideal future situation

Gadget authors can include a wasm module in their gadgets to implement custom changes in events in userspace.

Implementation options

We can use wazero, a WebAssembly runtime in Go that does not require dependencies with cgo.

Additional information

• design/002-containerized-gadgets.md
• Initial PoC demo [PoC] dns: implement parseLabelSequence in wasm #1985
• PoC for the ASG conference https://github.com/alban/inspektor-gadget/tree/alban_asg2023
• Discussion how to pass columns from server to client [RFE] Update GadgetInfo() rpc to avoid handling BTF/Wasm client-side #2131
• First PR adding wasm in the gadget images: image build: add wasm #2127
• Second PR executing wasm modules: Handling columns in wasm module #2204