pin k8s versions with integration tests

[Pothulapati]

Fixes #7112

This pins the default integration tests to run on the latest
k3d version by retrieving the latest k3d binary, while also
pinning helm-deep to run on v1.20+ (our min k8s version). T
his way we have integration tests running on both sides
(i.e latest and minimum)

Changes include:

• Update ./bin/k3d to always retrieve the latest k3d binary and
  use it.
• Update _test-helpers.sh to use min version image for helm-deep.
  here, we also replace flags that are removed and replaced
  with newer ones with the latest k3d binary.

I've tried to find a GitHub action for K3s, but most of them seem to
be have a had a release while ago, and not goes well with our plan of
somehow getting the latest k8s.

Signed-off-by: Tarun Pothulapati tarunpothulapati@outlook.com

[alpeb]

Thanks @Pothulapati . There's a bit of code repetition introduced in this change. Can you have start_single_test() simply react differently depending on some new arg? Similarly, I think we can get away with a single bin/k3d maybe through an env var (say K3D_VERSION) defaulting to "latest" (an env var instead of a script arg to avoid messing with the arg forwarding at the last line).

[olix0r]

integration test failures when loading images:

ERRO[0010] failed to import images in node 'k3d-helm-deep-server-0': docker failed to create exec config for node 'k3d-helm-deep-server-0': Error response from daemon: Container 8771c4151174fdf1dd9ff5c50939411154617172d36ff2e6392503ad062356bc is restarting, wait until the container is running 
50
ERRO[0018] failed to import images in node 'k3d-helm-deep-server-0': Exec process in node 'k3d-helm-deep-server-0' failed with exit code '137'

Also note that the latest k3d release supports specifying logical versions like +v1.20 per https://github.com/rancher/k3d/releases/tag/v5.1.0

[Pothulapati]

Updated this PR, to use the latest k3d binary always but use an older image version with helm-deep as some flags are replaced btw binaries, and it's hard to maintain them based on version.

[alpeb]

Changes look good, but for some reason the helm-deep integration test is still show v1.21:
https://github.com/linkerd/linkerd2/runs/4163956319?check_suite_focus=true#step:8:32

[Pothulapati]

@alpeb Yep, That is weird and I think that version is about the k3s wrapper. The k8s version seems to be the expected v1.20+ https://github.com/linkerd/linkerd2/runs/4163956319?check_suite_focus=true#step:8:61

[kleimkuhler]

Nice!