host-local: make allocation idempotent to multiple requests with same id

Signed-off-by: Bruce Ma <[email protected]>

plugins/ipam/host-local/backend/allocator/allocator.go

@@ -40,7 +40,7 @@ func NewIPAllocator(s *RangeSet, store backend.Store, id int) *IPAllocator {
  }
 }
 
-// Get alocates an IP
+// Get allocates an IP
 func (a *IPAllocator) Get(id string, ifname string, requestedIP net.IP) (*current.IPConfig, error) {
  a.store.Lock()
  defer a.store.Unlock()
@@ -73,24 +73,39 @@ func (a *IPAllocator) Get(id string, ifname string, requestedIP net.IP) (*curren
  gw = r.Gateway
 
  } else {
- iter, err := a.GetIter()
- if err != nil {
-  return nil, err
- }
- for {
- reservedIP, gw = iter.Next()
- if reservedIP == nil {
+ // try to get existing IPs which have been allocated to this id
+ existIPs := a.store.GetByID(id, ifname)
+ for _, existIP := range existIPs {
+  // check whether the existing IP belong to this range set
+  if r, err := a.rangeset.RangeFor(existIP); err == nil {
+  reservedIP = &net.IPNet{IP: existIP, Mask: r.Subnet.Mask}
+  gw = r.Gateway
  break
  }
+ }
 
- reserved, err := a.store.Reserve(id, ifname, reservedIP.IP, a.rangeID)
+ // if no existing IP was found, try to reserve a new one
+ if reservedIP == nil {
+ iter, err := a.GetIter()
  if err != nil {
  return nil, err
  }
-
- if reserved {
- break
+ for {
+ reservedIP, gw = iter.Next()
+ if reservedIP == nil {
+ break
+ }
+
+ reserved, err := a.store.Reserve(id, ifname, reservedIP.IP, a.rangeID)
+ if err != nil {
+ return nil, err
+ }
+
+ if reserved {
+ break
+ }
  }
+
  }
  }