Kubernetes: IPVS proxier keeps updating virtual server even if no service changes

[m1093782566]

Is this a BUG REPORT or FEATURE REQUEST?:

/kind bug

What happened:

IPVS proxier keep logging the following message, that is, IPVS proxier keeps updating virtual servers even if no service changes.

I0912 17:08:13.555614   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0x1}, Protocol:"TCP", Port:0x1bb, Scheduler:"rr", Flags:0x1, Timeout:0x2a30}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0x1}, Protocol:"TCP", Port:0x1bb, Scheduler:"rr", Flags:0x3, Timeout:0x2a30}
I0912 17:08:13.555659   18274 proxier.go:1291] IPVS service default/kubernetes:https was changed
I0912 17:08:13.556787   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0xa}, Protocol:"UDP", Port:0x35, Scheduler:"rr", Flags:0x0, Timeout:0x0}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0xa}, Protocol:"UDP", Port:0x35, Scheduler:"rr", Flags:0x2, Timeout:0x0}
I0912 17:08:13.556818   18274 proxier.go:1291] IPVS service kube-system/kube-dns:dns was changed
I0912 17:08:13.557872   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0xa}, Protocol:"TCP", Port:0x35, Scheduler:"rr", Flags:0x0, Timeout:0x0}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0xa}, Protocol:"TCP", Port:0x35, Scheduler:"rr", Flags:0x2, Timeout:0x0}
I0912 17:08:13.557902   18274 proxier.go:1291] IPVS service kube-system/kube-dns:dns-tcp was changed
I0912 17:08:13.558940   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0xb6}, Protocol:"TCP", Port:0xbda, Scheduler:"rr", Flags:0x1, Timeout:0x2a30}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0xb6}, Protocol:"TCP", Port:0xbda, Scheduler:"rr", Flags:0x3, Timeout:0x2a30}
....
I0912 17:09:13.455862   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0x1}, Protocol:"TCP", Port:0x1bb, Scheduler:"rr", Flags:0x1, Timeout:0x2a30}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0x1}, Protocol:"TCP", Port:0x1bb, Scheduler:"rr", Flags:0x3, Timeout:0x2a30}
I0912 17:09:13.455894   18274 proxier.go:1291] IPVS service default/kubernetes:https was changed
I0912 17:09:13.457139   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0xa}, Protocol:"UDP", Port:0x35, Scheduler:"rr", Flags:0x0, Timeout:0x0}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0xa}, Protocol:"UDP", Port:0x35, Scheduler:"rr", Flags:0x2, Timeout:0x0}
I0912 17:09:13.457169   18274 proxier.go:1291] IPVS service kube-system/kube-dns:dns was changed
I0912 17:09:13.458292   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0xa}, Protocol:"TCP", Port:0x35, Scheduler:"rr", Flags:0x0, Timeout:0x0}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0xa}, Protocol:"TCP", Port:0x35, Scheduler:"rr", Flags:0x2, Timeout:0x0}
I0912 17:09:13.458322   18274 proxier.go:1291] IPVS service kube-system/kube-dns:dns-tcp was changed
I0912 17:09:13.459468   18274 proxier.go:1279] vs is: &ipvs.VirtualServer{Address:net.IP{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xff, 0xff, 0xa, 0x0, 0x0, 0xb6}, Protocol:"TCP", Port:0xbda, Scheduler:"rr", Flags:0x1, Timeout:0x2a30}, applied vs is : &ipvs.VirtualServer{Address:net.IP{0xa, 0x0, 0x0, 0xb6}, Protocol:"TCP", Port:0xbda, Scheduler:"rr", Flags:0x3, Timeout:0x2a30}
...

PS. I added some logs to print the IPVS virtual server information.

What you expected to happen:

IPVS proxier should NOT update virtual server when no service changes.

How to reproduce it (as minimally and precisely as possible):

Just check the log message, you will find it.

Anything else we need to know?:

I think that's because the IPVS service flags differs. For example, create an IPVS service with Flags = 0, the Flags of created service will change to (0+2=2). Besides, if we create an IPVS service with Flags = 1, then the Flags of created service will change to (1+2=3).

See related issue: https://github.com/docker/libnetwork/issues/1921

Environment:

• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration**:
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Others:

/sig network
/assign @m1093782566

[m1093782566]

/cc @choury @Lion-Wei