Add socat back.

[Random-Liu]

io.Copy doesn't work for us. The main problem is that:

1. When one side (either pod side or user side) of portforward is closed, we should stop port forwarding.
2. When one side is closed, the io.Copy use that side as source will close, but the io.Copy use that side as dest won't. (io.Copy doesn't stop when dest is closed until there is new input from source)
3. However, we can't simply forcibly stop the hanging io.Copy by closing the source. Because TCP is bi-direction, even though one direction is closed (we know because one io.Copy stops), the other direction may not, and that io.Copy might be working. There is no way for us to know it now.

There should be some solution for this problem, and socat must have implemented that. We need more time to investigate it.

So let's switch back to socat for this release.

@abhi

Signed-off-by: Lantao Liu [email protected]

[abhi]

LGTM

[AkihiroSuda]

There should be some solution for this problem, and socat must have implemented that. We need more time to investigate it.

Could you open a github issue for tracking this?

[Random-Liu]

@AkihiroSuda Done. #730

Apply LGTM based on #729 (review)