ipam/host-local: support multiple IP ranges

This change allows the host-local allocator to allocate multiple IPs.
This is intended to enable dual-stack, but is not limited to only two
subnets or separate address families.

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

@@ -20,35 +20,51 @@ import (
 	"net"
 
 	"github.com/containernetworking/cni/pkg/types"
+	types020 "github.com/containernetworking/cni/pkg/types/020"
 )
 
 // IPAMConfig represents the IP related network configuration.
+// This nests Range because we initially only supported a single
+// range directly, and wish to preserve backwards compatability
 type IPAMConfig struct {
+	*Range
 	Name       string
-	Type       string        `json:"type"`
-	RangeStart net.IP        `json:"rangeStart"`
-	RangeEnd   net.IP        `json:"rangeEnd"`
-	Subnet     types.IPNet   `json:"subnet"`
-	Gateway    net.IP        `json:"gateway"`
-	Routes     []types.Route `json:"routes"`
-	DataDir    string        `json:"dataDir"`
-	ResolvConf string        `json:"resolvConf"`
-	Args       *IPAMArgs     `json:"-"`
+	Type       string         `json:"type"`
+	Routes     []*types.Route `json:"routes"`
+	DataDir    string         `json:"dataDir"`
+	ResolvConf string         `json:"resolvConf"`
+	Ranges     []Range        `json:"ranges"`
+	IPArgs     []net.IP       `json:"-"` // Requested IPs from CNI_ARGS and args
 }
 
-type IPAMArgs struct {
+type IPAMEnvArgs struct {
 	types.CommonArgs
 	IP net.IP `json:"ip,omitempty"`
 }
 
+type IPAMArgs struct {
+	IPs []net.IP `json:"ips"`
+}
+
+// The top-level network config, just so we can get the IPAM block
 type Net struct {
 	Name       string      `json:"name"`
 	CNIVersion string      `json:"cniVersion"`
 	IPAM       *IPAMConfig `json:"ipam"`
+	Args       *struct {
+		A *IPAMArgs `json:"cni"`
+	} `json:"args"`
+}
+
+type Range struct {
+	RangeStart net.IP      `json:"rangeStart,omitempty"` // The first ip, inclusive
+	RangeEnd   net.IP      `json:"rangeEnd,omitempty"`   // The last ip, inclusive
+	Subnet     types.IPNet `json:"subnet"`
+	Gateway    net.IP      `json:"gateway,omitempty"`
 }
 
 // NewIPAMConfig creates a NetworkConfig from the given network name.
-func LoadIPAMConfig(bytes []byte, args string) (*IPAMConfig, string, error) {
+func LoadIPAMConfig(bytes []byte, envArgs string) (*IPAMConfig, string, error) {
 	n := Net{}
 	if err := json.Unmarshal(bytes, &n); err != nil {
 		return nil, "", err
@@ -58,12 +74,71 @@ func LoadIPAMConfig(bytes []byte, args string) (*IPAMConfig, string, error) {
 		return nil, "", fmt.Errorf("IPAM config missing 'ipam' key")
 	}
 
-	if args != "" {
-		n.IPAM.Args = &IPAMArgs{}
-		err := types.LoadArgs(args, n.IPAM.Args)
+	// Parse custom IP from both env args *and* the top-level args config
+	if envArgs != "" {
+		e := IPAMEnvArgs{}
+		err := types.LoadArgs(envArgs, &e)
 		if err != nil {
 			return nil, "", err
 		}
+
+		if e.IP != nil {
+			n.IPAM.IPArgs = []net.IP{e.IP}
+		}
+	}
+
+	if n.Args != nil && n.Args.A != nil && len(n.Args.A.IPs) != 0 {
+		n.IPAM.IPArgs = append(n.IPAM.IPArgs, n.Args.A.IPs...)
+	}
+
+	for idx, _ := range n.IPAM.IPArgs {
+		if err := canonicalizeIP(&n.IPAM.IPArgs[idx]); err != nil {
+			return nil, "", fmt.Errorf("cannot understand ip: %v", err)
+		}
+	}
+
+	// If a single range (old-style config) is specified, move it to
+	// the Ranges array
+	if n.IPAM.Range != nil && n.IPAM.Range.Subnet.IP != nil {
+		n.IPAM.Ranges = append([]Range{*n.IPAM.Range}, n.IPAM.Ranges...)
+	}
+	n.IPAM.Range = nil
+
+	if len(n.IPAM.Ranges) == 0 {
+		return nil, "", fmt.Errorf("no IP ranges specified")
+	}
+
+	// Validate all ranges
+	numV4 := 0
+	numV6 := 0
+	for i, _ := range n.IPAM.Ranges {
+		if err := n.IPAM.Ranges[i].Canonicalize(); err != nil {
+			return nil, "", fmt.Errorf("Cannot understand range %d: %v", i, err)
+		}
+		if len(n.IPAM.Ranges[i].RangeStart) == 4 {
+			numV4++
+		} else {
+			numV6++
+		}
+	}
+
+	// CNI spec 0.2.0 and below supported only one v4 and v6 address
+	if numV4 > 1 || numV6 > 1 {
+		for _, v := range types020.SupportedVersions {
+			if n.CNIVersion == v {
+				return nil, "", fmt.Errorf("CNI version %v does not support more than 1 range per address family", n.CNIVersion)
+			}
+		}
+	}
+
+	// Check for overlaps
+	l := len(n.IPAM.Ranges)
+	for i, r1 := range n.IPAM.Ranges[:l-1] {
+		for j, r2 := range n.IPAM.Ranges[i+1:] {
+			if r1.Overlaps(&r2) {
+				return nil, "", fmt.Errorf("Range %d overlaps with range %d", i, (i + j + 1))
+			}
+		}
 	}
 
 	// Copy net name into IPAM so not to drag Net struct around
@@ -71,14 +146,3 @@ func LoadIPAMConfig(bytes []byte, args string) (*IPAMConfig, string, error) {
 
 	return n.IPAM, n.CNIVersion, nil
 }
-
-func convertRoutesToCurrent(routes []types.Route) []*types.Route {
-	var currentRoutes []*types.Route
-	for _, r := range routes {
-		currentRoutes = append(currentRoutes, &types.Route{
-			Dst: r.Dst,
-			GW:  r.GW,
-		})
-	}
-	return currentRoutes
-}