Decide what the local networks are at runtime, not once at startup.

probe/host/reporter.go

@@ -1,6 +1,7 @@
 package host
 
 import (
+	"net"
 	"runtime"
 	"time"
 
@@ -33,32 +34,50 @@ const (
 
 // Reporter generates Reports containing the host topology.
 type Reporter struct {
-	hostID    string
-	hostName  string
-	localNets report.Networks
+	hostID   string
+	hostName string
 }
 
 // NewReporter returns a Reporter which produces a report containing host
 // topology for this host.
-func NewReporter(hostID, hostName string, localNets report.Networks) *Reporter {
+func NewReporter(hostID, hostName string) *Reporter {
 	return &Reporter{
-		hostID:    hostID,
-		hostName:  hostName,
-		localNets: localNets,
+		hostID:   hostID,
+		hostName: hostName,
 	}
 }
 
 // Name of this reporter, for metrics gathering
 func (Reporter) Name() string { return "Host" }
 
+// LocalNetworks is exported for mocking
+var GetLocalNetworks = func() ([]*net.IPNet, error) {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return nil, err
+	}
+	localNets := report.Networks{}
+	for _, addr := range addrs {
+		// Not all addrs are IPNets.
+		if ipNet, ok := addr.(*net.IPNet); ok {
+			localNets = append(localNets, ipNet)
+		}
+	}
+	return localNets, nil
+}
+
 // Report implements Reporter.
 func (r *Reporter) Report() (report.Report, error) {
 	var (
 		rep        = report.MakeReport()
 		localCIDRs []string
 	)
 
-	for _, localNet := range r.localNets {
+	localNets, err := GetLocalNetworks()
+	if err != nil {
+		return rep, nil
+	}
+	for _, localNet := range localNets {
 		localCIDRs = append(localCIDRs, localNet.String())
 	}
 

probe/host/reporter_test.go

@@ -29,7 +29,6 @@ func TestReporter(t *testing.T) {
 		uptime      = "278h55m43s"
 		kernel      = "release version"
 		_, ipnet, _ = net.ParseCIDR(network)
-		localNets   = report.Networks([]*net.IPNet{ipnet})
 	)
 
 	mtime.NowForce(timestamp)
@@ -41,21 +40,24 @@ func TestReporter(t *testing.T) {
 		oldGetUptime           = host.GetUptime
 		oldGetCPUUsagePercent  = host.GetCPUUsagePercent
 		oldGetMemoryUsageBytes = host.GetMemoryUsageBytes
+		oldGetLocalNetworks    = host.GetLocalNetworks
 	)
 	defer func() {
 		host.GetKernelVersion = oldGetKernelVersion
 		host.GetLoad = oldGetLoad
 		host.GetUptime = oldGetUptime
 		host.GetCPUUsagePercent = oldGetCPUUsagePercent
 		host.GetMemoryUsageBytes = oldGetMemoryUsageBytes
+		host.GetLocalNetworks = oldGetLocalNetworks
 	}()
 	host.GetKernelVersion = func() (string, error) { return release + " " + version, nil }
 	host.GetLoad = func(time.Time) report.Metrics { return metrics }
 	host.GetUptime = func() (time.Duration, error) { return time.ParseDuration(uptime) }
 	host.GetCPUUsagePercent = func() (float64, float64) { return 30.0, 100.0 }
 	host.GetMemoryUsageBytes = func() (float64, float64) { return 60.0, 100.0 }
+	host.GetLocalNetworks = func() ([]*net.IPNet, error) { return []*net.IPNet{ipnet}, nil }
 
-	rpt, err := host.NewReporter(hostID, hostname, localNets).Report()
+	rpt, err := host.NewReporter(hostID, hostname).Report()
 	if err != nil {
 		t.Fatal(err)
 	}

prog/probe.go

@@ -112,18 +112,6 @@ func probeMain() {
 	log.Printf("probe starting, version %s, ID %s", version, probeID)
 	go check()
 
-	addrs, err := net.InterfaceAddrs()
-	if err != nil {
-		log.Fatal(err)
-	}
-	localNets := report.Networks{}
-	for _, addr := range addrs {
-		// Not all addrs are IPNets.
-		if ipNet, ok := addr.(*net.IPNet); ok {
-			localNets = append(localNets, ipNet)
-		}
-	}
-
 	if len(flag.Args()) > 0 {
 		targets = flag.Args()
 	}
@@ -154,7 +142,7 @@ func probeMain() {
 	p.AddTicker(processCache)
 	p.AddReporter(
 		endpointReporter,
-		host.NewReporter(hostID, hostName, localNets),
+		host.NewReporter(hostID, hostName),
 		process.NewReporter(processCache, hostID, process.GetDeltaTotalJiffies),
 	)
 	p.AddTagger(probe.NewTopologyTagger(), host.NewTagger(hostID, probeID))