Robustness: Exit if the plugin is taking too long

If the plugin (either networking or IPAM) takes more than 30 seconds
then panic.

Fixes projectcalico/calico#2098

calico.go

@@ -470,6 +470,9 @@ func cmdDel(args *skel.CmdArgs) error {
 var VERSION string
 
 func main() {
+	// Panic if the plugin takes too long to run.
+	utils.StartSelfDestructTimer()
+
 	// Set up logging formatting.
 	logrus.SetFormatter(&logutils.Formatter{})
 

ipam/calico-ipam.go

@@ -38,6 +38,9 @@ import (
 var VERSION string
 
 func main() {
+	// Panic if the plugin takes too long to run.
+	utils.StartSelfDestructTimer()
+
 	// Set up logging formatting.
 	logrus.SetFormatter(&logutils.Formatter{})
 

utils/utils.go

@@ -24,6 +24,8 @@ import (
 	"regexp"
 	"strings"
 
+	"time"
+
 	"github.com/containernetworking/cni/pkg/skel"
 	cnitypes "github.com/containernetworking/cni/pkg/types"
 	"github.com/containernetworking/cni/pkg/types/current"
@@ -525,3 +527,12 @@ func ParsePools(pools []string, isv4 bool) ([]cnet.IPNet, error) {
 	}
 	return result, nil
 }
+
+// Causes the current process to exit if it's been running for too long
+func StartSelfDestructTimer() {
+	go func() {
+		time.Sleep(30 * time.Second)
+		panic("Execution took too long.")
+	}()
+
+}