Add worker tagging (#862)

This allows workers to have tags assigned to them, which can then be filtered to control which targets they are allowed to serve.

internal/cmd/commands/server/server.go

@@ -544,7 +544,7 @@ func (c *Command) WaitForInterrupt() int {
 			shutdownTriggered = true
 
 		case <-c.SighupCh:
-			c.UI.Output("==> Boundary controller reload triggered")
+			c.UI.Output("==> Boundary server reload triggered")
 
 			// Check for new log level
 			var level hclog.Level
@@ -589,7 +589,7 @@ func (c *Command) WaitForInterrupt() int {
 
 		RUNRELOADFUNCS:
 			if err := c.Reload(); err != nil {
-				c.UI.Error(fmt.Errorf("Error(s) were encountered during controller reload: %w", err).Error())
+				c.UI.Error(fmt.Errorf("Error(s) were encountered during server reload: %w", err).Error())
 			}
 
 		case <-c.SigUSR2Ch:

internal/cmd/commands/targets/funcs.go

@@ -41,6 +41,9 @@ func generateTargetTableOutput(in *targets.Target) string {
 	if in.Description != "" {
 		nonAttributeMap["Description"] = in.Description
 	}
+	if in.WorkerFilter != "" {
+		nonAttributeMap["Worker Filter"] = in.WorkerFilter
+	}
 
 	maxLength := base.MaxAttributesLength(nonAttributeMap, in.Attributes, keySubstMap)
 

internal/cmd/commands/targets/tcp.go

@@ -11,6 +11,7 @@ import (
 	"github.com/hashicorp/boundary/internal/cmd/base"
 	"github.com/hashicorp/boundary/internal/cmd/common"
 	"github.com/hashicorp/boundary/sdk/strutil"
+	"github.com/hashicorp/go-bexpr"
 	"github.com/mitchellh/cli"
 	"github.com/posener/complete"
 )
@@ -27,6 +28,7 @@ type TcpCommand struct {
 	flagDefaultPort            string
 	flagSessionMaxSeconds      string
 	flagSessionConnectionLimit string
+	flagWorkerFilter           string
 }
 
 func (c *TcpCommand) Synopsis() string {
@@ -34,8 +36,8 @@ func (c *TcpCommand) Synopsis() string {
 }
 
 var tcpFlagsMap = map[string][]string{
-	"create": {"scope-id", "name", "description", "default-port", "session-max-seconds", "session-connection-limit"},
-	"update": {"id", "name", "description", "version", "default-port", "session-max-seconds", "session-connection-limit"},
+	"create": {"scope-id", "name", "description", "default-port", "session-max-seconds", "session-connection-limit", "worker-filter"},
+	"update": {"id", "name", "description", "version", "default-port", "session-max-seconds", "session-connection-limit", "worker-filter"},
 }
 
 func (c *TcpCommand) Help() string {
@@ -91,6 +93,12 @@ func (c *TcpCommand) Flags() *base.FlagSets {
 				Target: &c.flagSessionConnectionLimit,
 				Usage:  "The maximum number of connections allowed for a session. -1 means unlimited.",
 			})
+		case "worker-filter":
+			f.StringVar(&base.StringVar{
+				Name:   "worker-filter",
+				Target: &c.flagWorkerFilter,
+				Usage:  "A boolean expression to filter which workers can handle sessions for this target.",
+			})
 		}
 	}
 
@@ -196,6 +204,18 @@ func (c *TcpCommand) Run(args []string) int {
 		opts = append(opts, targets.WithSessionConnectionLimit(int32(limit)))
 	}
 
+	switch c.flagWorkerFilter {
+	case "":
+	case "null":
+		opts = append(opts, targets.DefaultWorkerFilter())
+	default:
+		if _, err := bexpr.CreateEvaluator(c.flagWorkerFilter); err != nil {
+			c.UI.Error(fmt.Sprintf("Unable to successfully parse filter expression: %s", err))
+			return 1
+		}
+		opts = append(opts, targets.WithWorkerFilter(c.flagWorkerFilter))
+	}
+
 	targetClient := targets.NewClient(client)
 
 	// Perform check-and-set when needed