LogDog: Add project namespace to Butler/Collector.

client/internal/logdog/butler/butler.go

Index: client/internal/logdog/butler/butler.go
diff --git a/client/internal/logdog/butler/butler.go b/client/internal/logdog/butler/butler.go
index 8b580d85b7a0af3ee36640b416389897e90851fb..8b0684a451f56183d2a0f2ab7153d2473970aba6 100644
--- a/client/internal/logdog/butler/butler.go
+++ b/client/internal/logdog/butler/butler.go
@@ -17,6 +17,7 @@ import (
 	"github.com/luci/luci-go/client/internal/logdog/butler/streamserver"
 	"github.com/luci/luci-go/client/logdog/butlerlib/streamproto"
 	"github.com/luci/luci-go/common/clock"
+	"github.com/luci/luci-go/common/config"
 	"github.com/luci/luci-go/common/iotools"
 	"github.com/luci/luci-go/common/logdog/types"
 	log "github.com/luci/luci-go/common/logging"
@@ -46,8 +47,14 @@ type Config struct {
 	// OutputWorkers is the number of simultaneous goroutines that will be used
 	// to output Butler log data. If zero, DefaultOutputWorkers will be used.
 	OutputWorkers int
+
+	// Project is the project that the log stream will be bound to.
+	Project config.ProjectName
 	// Prefix is the log stream common prefix value.
 	Prefix types.StreamName
+	// Secret is the prefix secret that will be used for streams generated by this
+	// Butler.
+	Secret types.PrefixSecret
 
 	// BufferLogs, if true, instructs the butler to buffer collected log data
 	// before sending it to Output.
@@ -71,8 +78,18 @@ func (c *Config) Validate() error {
 	if c.Output == nil {
 		return errors.New("butler: an Output must be supplied")
 	}
+	// TODO(dnj): Empty project should not validate here once projects are
+	// mandatory.
+	if c.Project != "" {
+		if err := c.Project.Validate(); err != nil {
+			return fmt.Errorf("invalid project: %v", err)
+		}
+	}
 	if err := c.Prefix.Validate(); err != nil {
-		return errors.New("butler: invalid Prefix")
+		return fmt.Errorf("invalid prefix: %v", err)
+	}
+	if err := c.Secret.Validate(); err != nil {
+		return fmt.Errorf("invalid secret: %v", err)
 	}
 	return nil
 }
@@ -135,6 +152,9 @@ func New(ctx context.Context, config Config) (*Butler, error) {
 
 	bc := bundler.Config{
 		Clock:            clock.Get(ctx),
+		Project:          config.Project,
+		Prefix:           config.Prefix,
+		Secret:           config.Secret,
 		MaxBufferedBytes: streamBufferSize,
 		MaxBundleSize:    config.Output.MaxSize(),
 	}