Add ipvsadm tool in favor of IPVS implement of service

[Crazykev]

this PR is IPVS service workflow in hyperstart.

1. using ipvsadm tool to manipulate ipvs rules, ipvsadm is static built in hyper container.
   2. add two method using ipvsadm -Sn to get ipvs rules and ipvsadm -R to load ipvs rules.
   3. use ipvsadm -C to clear ipvs rules, clear is specified.

/cc @feiskyer @resouer

[Jimmy-Xu]

Can one of the admins verify this patch?

[laijs]

is hyperstart-exec(#246) suitable for it?
I will add the runv's wrapper for hyperstart-exec later.

[feiskyer]

is hyperstart-exec(#246) suitable for it?

Agreed with this. it's better to reuse hyperstart-exec.

[Crazykev]

@laijs @feiskyer Agreed. This part of code is written months ago, sorry for not keeping update with this project recently.
AFAIK, to support ipvs service feature, only need to meet

1. exec ipvsadm in pod network namespace.
2. exec ipvsadm with stdin attached. this is required by ipvsadm -R, will read rules from stdin.

I believe it's not hard to meet with hyperstart-exec, will read through the latest code later and find out how to achieve that, thanks.

[mqliang]

@Crazykev @feiskyer @resouer Could you guys take a look at https://github.com/mqliang/libipvs, a pure go lib work with IPVS using generic netlink socket, thus removing the runtime dependency of ipvsadm tool

[feiskyer]

@mqliang Hmm, hyperstart is written by C. I think hyperstart-exec(#246) is enough for ipvs load balancing, so we could keep all the control logic outside of hyperstart and don't make it too heavy.

[Jimmy-Xu]

Can one of the admins verify this patch?

[feiskyer]

LGTM.

@laijs Do you want to have another look?

[laijs]

could you please directly copy all the above binaries into /tmp/hyperstart-rootfs/sbin?

[Crazykev]

Updated, is this what you want?

[Crazykev]

@laijs CI green now.