internal/databroker: store server version (#1121)

Storing server version when creating new server. After then, we can
retrieve the version from backend when server restart.

With storage backend which supports persistent, the server version
won't change after restarting.

internal/databroker/server_test.go

@@ -0,0 +1,73 @@
+package databroker
+
+import (
+	"context"
+	"testing"
+
+	"github.com/golang/protobuf/ptypes"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+
+	"github.com/pomerium/pomerium/internal/log"
+	"github.com/pomerium/pomerium/pkg/grpc/databroker"
+	"github.com/pomerium/pomerium/pkg/storage"
+)
+
+func newServer(cfg *serverConfig) *Server {
+	return &Server{
+		version: uuid.New().String(),
+		cfg:     cfg,
+		log:     log.With().Str("service", "databroker").Logger(),
+
+		byType:   make(map[string]storage.Backend),
+		onchange: NewSignal(),
+	}
+}
+
+func TestServer_initVersion(t *testing.T) {
+	cfg := newServerConfig()
+	t.Run("nil db", func(t *testing.T) {
+		srv := newServer(cfg)
+		srvVersion := uuid.New().String()
+		srv.version = srvVersion
+		srv.byType[recordTypeServerVersion] = nil
+		srv.initVersion()
+		assert.Equal(t, srvVersion, srv.version)
+	})
+	t.Run("new server with random version", func(t *testing.T) {
+		srv := newServer(cfg)
+		ctx := context.Background()
+		db := srv.getDB(recordTypeServerVersion)
+		r := db.Get(ctx, serverVersionKey)
+		assert.Nil(t, r)
+		srvVersion := uuid.New().String()
+		srv.version = srvVersion
+		srv.initVersion()
+		assert.Equal(t, srvVersion, srv.version)
+		r = db.Get(ctx, serverVersionKey)
+		assert.NotNil(t, r)
+		var sv databroker.ServerVersion
+		assert.NoError(t, ptypes.UnmarshalAny(r.GetData(), &sv))
+		assert.Equal(t, srv.version, sv.Version)
+	})
+	t.Run("init version twice should get the same version", func(t *testing.T) {
+		srv := newServer(cfg)
+		ctx := context.Background()
+		db := srv.getDB(recordTypeServerVersion)
+		r := db.Get(ctx, serverVersionKey)
+		assert.Nil(t, r)
+		srvVersion := uuid.New().String()
+		srv.version = srvVersion
+		srv.initVersion()
+		assert.Equal(t, srvVersion, srv.version)
+		r = db.Get(ctx, serverVersionKey)
+		assert.NotNil(t, r)
+		var sv databroker.ServerVersion
+		assert.NoError(t, ptypes.UnmarshalAny(r.GetData(), &sv))
+		assert.Equal(t, srv.version, sv.Version)
+
+		// re-init version should get the same value as above
+		srv.initVersion()
+		assert.Equal(t, srvVersion, srv.version)
+	})
+}