Forward OS/Kernel version to checkpoint

Useful to prioritize ebpf testing

Also:
* Make treatment of kernel release and version consistent across Darwin/Linux

prog/app.go

@@ -246,6 +246,7 @@ func appMain(flags appFlags) {
 	checkpoint.CheckInterval(&checkpoint.CheckParams{
 		Product: "scope-app",
 		Version: app.Version,
+		Flags:   makeBaseCheckpointFlags(),
 	}, versionCheckPeriod, func(r *checkpoint.CheckResponse, err error) {
 		if err != nil {
 			log.Errorf("Error checking version: %v", err)

prog/main.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"os"
 	"regexp"
+	"runtime"
 	"strconv"
 	"strings"
 	"time"
@@ -16,6 +17,7 @@ import (
 	"github.com/weaveworks/scope/app"
 	"github.com/weaveworks/scope/common/xfer"
 	"github.com/weaveworks/scope/probe/appclient"
+	"github.com/weaveworks/scope/probe/host"
 	"github.com/weaveworks/scope/probe/kubernetes"
 	"github.com/weaveworks/scope/render"
 	"github.com/weaveworks/weave/common"
@@ -215,6 +217,18 @@ func logCensoredArgs() {
 	log.Infof("command line args:%s", prettyPrintedArgs)
 }
 
+func makeBaseCheckpointFlags() map[string]string {
+	release, _, err := host.GetKernelReleaseAndVersion()
+	if err != nil {
+		release = "unknown"
+	}
+	return map[string]string{
+		// Inconsistent key (using a dash) to match Weave Net
+		"kernel-version": release,
+		"os":             runtime.GOOS,
+	}
+}
+
 func main() {
 	var (
 		flags                            = flags{}

prog/probe.go

@@ -91,7 +91,8 @@ func probeMain(flags probeFlags, targets []appclient.Target) {
 		hostID   = hostName // TODO(pb): we should sanitize the hostname
 	)
 	log.Infof("probe starting, version %s, ID %s", version, probeID)
-	checkpointFlags := map[string]string{}
+
+	checkpointFlags := makeBaseCheckpointFlags()
 	if flags.kubernetesEnabled {
 		checkpointFlags["kubernetes_enabled"] = "true"
 	}