refactor(worker): Validate listener configuration in New

With this change, the Worker is now aware of its own listeners in a
more codified and structured way.

These changes have already been made in the controller on
8d48a8515c. They're now made on the
worker for similar reasons.

internal/servers/worker/worker.go

@@ -14,6 +14,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/hashicorp/boundary/internal/cmd/base"
 	"github.com/hashicorp/boundary/internal/cmd/config"
 	pbs "github.com/hashicorp/boundary/internal/gen/controller/servers/services"
 	"github.com/hashicorp/boundary/internal/observability/event"
@@ -45,6 +46,8 @@ type Worker struct {
 	controllerSessionConn *atomic.Value
 	sessionInfoMap        *sync.Map
 
+	listeners []*base.ServerListener
+
 	// We store the current set in an atomic value so that we can add
 	// reload-on-sighup behavior later
 	tags *atomic.Value
@@ -105,6 +108,23 @@ func New(conf *Config) (*Worker, error) {
 		}
 	}
 
+	for i := range conf.Listeners {
+		l := conf.Listeners[i]
+		if l == nil || l.Config == nil || l.Config.Purpose == nil {
+			continue
+		}
+		if len(l.Config.Purpose) != 1 {
+			return nil, fmt.Errorf("found listener with multiple purposes %q", strings.Join(l.Config.Purpose, ","))
+		}
+		switch l.Config.Purpose[0] {
+		case "proxy":
+			w.listeners = append(w.listeners, l)
+		}
+	}
+	if len(w.listeners) == 0 {
+		return nil, fmt.Errorf("no proxy listeners found")
+	}
+
 	return w, nil
 }
 

internal/servers/worker/worker_test.go

@@ -0,0 +1,100 @@
+package worker
+
+import (
+	"testing"
+
+	"github.com/hashicorp/boundary/internal/cmd/base"
+	"github.com/hashicorp/boundary/internal/cmd/config"
+	"github.com/hashicorp/go-hclog"
+	"github.com/hashicorp/go-secure-stdlib/configutil/v2"
+	"github.com/hashicorp/go-secure-stdlib/listenerutil"
+	"github.com/stretchr/testify/require"
+)
+
+func TestWorkerNewListenerConfig(t *testing.T) {
+	tests := []struct {
+		name       string
+		in         *Config
+		expErr     bool
+		expErrMsg  string
+		assertions func(t *testing.T, w *Worker)
+	}{
+		{
+			name:      "nil listeners",
+			in:        &Config{Server: &base.Server{Listeners: nil}},
+			expErr:    true,
+			expErrMsg: "no proxy listeners found",
+		},
+		{
+			name:      "zero listeners",
+			in:        &Config{Server: &base.Server{Listeners: []*base.ServerListener{}}},
+			expErr:    true,
+			expErrMsg: "no proxy listeners found",
+		},
+		{
+			name: "populated with nil values",
+			in: &Config{
+				Server: &base.Server{
+					Listeners: []*base.ServerListener{
+						nil,
+						{Config: nil},
+						{Config: &listenerutil.ListenerConfig{Purpose: nil}},
+					},
+				},
+			},
+			expErr:    true,
+			expErrMsg: "no proxy listeners found",
+		},
+		{
+			name: "multiple purposes",
+			in: &Config{
+				Server: &base.Server{
+					Listeners: []*base.ServerListener{
+						nil,
+						{Config: nil},
+						{Config: &listenerutil.ListenerConfig{Purpose: []string{"api", "proxy"}}},
+					},
+				},
+			},
+			expErr:    true,
+			expErrMsg: `found listener with multiple purposes "api,proxy"`,
+		},
+		{
+			name: "valid listeners",
+			in: &Config{
+				Server: &base.Server{
+					Listeners: []*base.ServerListener{
+						{Config: &listenerutil.ListenerConfig{Purpose: []string{"api"}}},
+						{Config: &listenerutil.ListenerConfig{Purpose: []string{"proxy"}}},
+						{Config: &listenerutil.ListenerConfig{Purpose: []string{"proxy"}}},
+						{Config: &listenerutil.ListenerConfig{Purpose: []string{"cluster"}}},
+					},
+				},
+			},
+			expErr: false,
+			assertions: func(t *testing.T, w *Worker) {
+				require.Len(t, w.listeners, 2)
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// New() panics if these aren't set
+			tt.in.Logger = hclog.Default()
+			tt.in.RawConfig = &config.Config{SharedConfig: &configutil.SharedConfig{DisableMlock: true}}
+
+			w, err := New(tt.in)
+			if tt.expErr {
+				require.EqualError(t, err, tt.expErrMsg)
+				require.Nil(t, w)
+				return
+			}
+
+			require.NoError(t, err)
+			if tt.assertions != nil {
+				tt.assertions(t, w)
+			}
+		})
+	}
+}