write out metadata json and plist files to root install directory

cmd/launcher/internal/record_metadata.go

@@ -0,0 +1,127 @@
+package internal
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
+	"github.com/groob/plist"
+	"github.com/kolide/kit/version"
+	"github.com/kolide/launcher/pkg/agent/types"
+)
+
+type (
+	// metadataWriter is used as a subscriber for the kolide_server_data
+	// subsystem. whenever new data is received, it will rewrite the metadata.json
+	// and metadata.plist files to our root install directory
+	metadataWriter struct {
+		logger log.Logger
+		k      types.Knapsack
+	}
+	metadata struct {
+		DeviceId           string `json:"device_id" plist:"device_id"`
+		OrganizationId     string `json:"organization_id" plist:"organization_id"`
+		OrganizationMunemo string `json:"organization_munemo" plist:"organization_munemo"`
+		Timestamp          string `json:"timestamp" plist:"timestamp"`
+		Version            string `json:"version" plist:"version"`
+	}
+)
+
+func NewMetadataWriter(logger log.Logger, k types.Knapsack) *metadataWriter {
+	return &metadataWriter{
+		logger: logger,
+		k:      k,
+	}
+}
+
+func (mw *metadataWriter) Ping() {
+	metadata := newMetadataTemplate()
+	if err := mw.populateLatestServerData(metadata); err != nil {
+		level.Debug(mw.logger).Log("msg", "unable to collect latest server data, metadata files will be incomplete", "err", err)
+	}
+
+	if err := mw.recordMetadata(metadata); err != nil {
+		level.Debug(mw.logger).Log("msg", "unable to write out metadata files", "err", err)
+	}
+}
+
+func newMetadataTemplate() *metadata {
+	return &metadata{
+		Timestamp: time.Now().String(),
+		Version:   version.Version().Version,
+	}
+}
+
+func (mw *metadataWriter) populateLatestServerData(metadata *metadata) error {
+	store := mw.k.ServerProvidedDataStore()
+
+	if store == nil {
+		return errors.New("ServerProvidedDataStore is uninitialized")
+	}
+
+	metadata.DeviceId = mw.getServerDataValue(store, "device_id")
+	metadata.OrganizationId = mw.getServerDataValue(store, "organization_id")
+	metadata.OrganizationMunemo = mw.getServerDataValue(store, "munemo")
+
+	return nil
+}
+
+// recordMetadata writes out both a json and plist (for darwin) file including all information
+// in the metadata struct to the root install directory
+func (mw *metadataWriter) recordMetadata(metadata *metadata) error {
+	metadataJSONFile := filepath.Join(mw.k.RootDirectory(), "metadata.json")
+	metadataJSON, err := json.MarshalIndent(metadata, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	if err = os.WriteFile(metadataJSONFile, metadataJSON, 0644); err != nil {
+		return err
+	}
+
+	if runtime.GOOS != "darwin" {
+		return nil
+	}
+
+	metadataPlistFile := filepath.Join(mw.k.RootDirectory(), "metadata.plist")
+	metadataPlist, err := plist.MarshalIndent(metadata, "  ")
+
+	if err != nil {
+		return err
+	}
+
+	if err = os.WriteFile(metadataPlistFile, metadataPlist, 0644); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (mw *metadataWriter) getServerDataValue(store types.GetterSetterDeleterIteratorUpdater, key string) string {
+	val, err := store.Get([]byte(key))
+	if err != nil {
+		level.Debug(mw.logger).Log(
+			"msg", fmt.Sprintf("unable to collect value for %s from server_data, will re-attempt on next update", key),
+			"err", err,
+		)
+
+		return ""
+	}
+
+	if string(val) == "" {
+		level.Debug(mw.logger).Log(
+			"msg", fmt.Sprintf("server_data was missing value for %s, will re-attempt on next update", key),
+			"err", err,
+		)
+
+		return ""
+	}
+
+	return string(val)
+}

cmd/launcher/launcher.go

@@ -347,6 +347,19 @@ func runLauncher(ctx context.Context, cancel func(), opts *launcher.Options) err
 			controlService.RegisterSubscriber(authTokensSubsystemName, logShipper)
 			controlService.RegisterSubscriber(agentFlagsSubsystemName, logShipper)
 		}
+
+		if metadataWriter := internal.NewMetadataWriter(logger, k); metadataWriter == nil {
+			level.Debug(logger).Log(
+				"msg", "unable to set up metadata writer",
+				"err", err,
+			)
+		} else {
+			controlService.RegisterSubscriber(serverDataSubsystemName, metadataWriter)
+			// explicitly trigger the ping at least once to ensure updated metadata is written
+			// on upgrades, the subscriber will continue to do this automatically when new
+			// information is made available from server_data (e.g. on a fresh install)
+			metadataWriter.Ping()
+		}
 	}
 
 	runEECode := k.ControlServerURL() != "" || k.IAmBreakingEELicense()