integration-test: Use veth pair instead of lo

[kevinji]

Fixes #422. I split the initial codegen commit out to #919 to clean this PR up.

I would like some help debugging the last 4 test failures:

---- tests::smoke::list_loaded_maps stdout ----
Entered network namespace aya-test-404672-4
thread 'tests::smoke::list_loaded_maps' panicked at test/integration-test/src/tests/smoke.rs:117:23:
called `Result::unwrap()` on an `Err` value: LoadError { io_error: Os { code: 22, kind: InvalidInput, message: "Invalid argument" }, verifier_log:  }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Exited network namespace aya-test-404672-4

---- tests::smoke::list_loaded_programs stdout ----
Entered network namespace aya-test-404672-5
thread 'tests::smoke::list_loaded_programs' panicked at test/integration-test/src/tests/smoke.rs:84:23:
called `Result::unwrap()` on an `Err` value: LoadError { io_error: Os { code: 22, kind: InvalidInput, message: "Invalid argument" }, verifier_log:  }
Exited network namespace aya-test-404672-5

---- tests::xdp::af_xdp stdout ----
Entered network namespace aya-test-404672-6
thread 'tests::xdp::af_xdp' panicked at test/integration-test/src/tests/xdp.rs:57:22:
called `Result::unwrap()` on an `Err` value: Errno(19: No such device)
Exited network namespace aya-test-404672-6

---- tests::xdp::cpumap_chain stdout ----
Entered network namespace aya-test-404672-7
thread 'tests::xdp::cpumap_chain' panicked at test/integration-test/src/tests/xdp.rs:182:5:
assertion `left == right` failed
  left: 0
 right: 1
Exited network namespace aya-test-404672-7

I'm not sure if introducing the network namespace caused behavior to now be different.

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[astoycos]

Thanks for starting this @kevinji!! I'm going to start checking this out, Looks like we're still failing on macos though

Failed to set up veth pair (aya-test-1, aya-test-2): Not supported (os error 95)

[astoycos]

Additionally you consider using dummy interfaces here rather than veth pairs? (as mentioned in #422) ?

[kevinji]

@astoycos I saw a comment in #561 suggesting veth pairs instead of dummies so that's why I went with this approach. I'll look into why the macOS VM tests are failing.

[astoycos]

Ack just read that, sounds good thanks!

[kevinji]

@astoycos I'm having trouble debugging the exact issue as I'm unable to get the QEMU setup working locally, so have been (slowly) trying to debug while pushing changes to CI.

My current hypothesis is that since the integration tests run as the /init process on initramfs, perhaps some veth module is not yet loaded which causes creation to fail. I ran the equivalent ip link command to try to create a veth and ran into similar issues. It's also possible that veth creation relies on something on the filesystem that it can't access for some reason during the /init script.

[mergify]

@kevinji, this pull request is now in conflict and requires a rebase.