There is no need to call GetIPAMConfig multiple times during the AssignIP process

[gongzixiangyuan]

Expected Behavior

When CNI is called, the interaction with ApiServer should be minimized.

Current Behavior

calico/libcalico-go/lib/ipam/ipam.go

Line 871 in dc49320

cfg, err := c.GetIPAMConfig(ctx)

calico/libcalico-go/lib/ipam/ipam.go

Line 888 in dc49320

cfg, err = c.GetIPAMConfig(ctx)

Possible Solution

Can IPAMConfig be used as a property of ipamClient?

[caseydavenport]

We do need to call GetIPAMConfig each time, as the configuration may have changed since the last call (or since the client was instantiated).

We could adjust so that we are instead watching IPAM config, to avoid the extra Get call.