tool runner: mesh/stream.publish says an event on the calling bundle's own bound stream (A-42)

Builds: design 42 zfs-owns-zfs §25, §24, lead answer A-42

node-tools/internal/bus/bindings.go

@@ -275,6 +275,41 @@ func (c *Conn) StreamFill(module string, r buscalls.StreamRequest) (buscalls.Str
 	return c.streamFill(b.Stream)
 }
 
+// StreamPublish says one event on the module's own bound stream, by an acknowledged publish on the binding's subject plus
+// "." plus the event, the id as the message id (design 42 zfs-owns-zfs, A-42). The module's own binding alone: another
+// module's, and a binding that is not a stream, are refused by Binding.
+func (c *Conn) StreamPublish(module string, r buscalls.StreamPublishRequest) (buscalls.StreamPublished, error) {
+	b, err := c.streamBinding(module, r.Stream)
+	if err != nil {
+		return buscalls.StreamPublished{}, err
+	}
+	if b.Subject == "" {
+		return buscalls.StreamPublished{}, fmt.Errorf("%s's stream %q has no subject to say an event on", module, r.Stream)
+	}
+	if r.Event == "" || strings.ContainsAny(r.Event, " *>\t\r\n") || strings.HasPrefix(r.Event, ".") || strings.HasSuffix(r.Event, ".") {
+		return buscalls.StreamPublished{}, fmt.Errorf("the event %q is not a name to say on %s's stream %q", r.Event, module, r.Stream)
+	}
+	body := []byte(r.Body)
+	if len(body) == 0 {
+		body = []byte("null")
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), StateTimeout)
+	defer cancel()
+	js, err := c.jetStream()
+	if err != nil {
+		return buscalls.StreamPublished{}, err
+	}
+	var opts []jetstream.PublishOpt
+	if r.ID != "" {
+		opts = append(opts, jetstream.WithMsgID(r.ID))
+	}
+	ack, err := js.Publish(ctx, b.Subject+"."+r.Event, body, opts...)
+	if err != nil {
+		return buscalls.StreamPublished{}, fmt.Errorf("the event %s was not acknowledged on %s's stream %q: %w", r.Event, module, r.Stream, err)
+	}
+	return buscalls.StreamPublished{Sequence: ack.Sequence}, nil
+}
+
 // StreamReadMost is the most messages one read answers.
 const StreamReadMost = 1000
 

node-tools/internal/bus/bindings_test.go

@@ -2,6 +2,7 @@ package bus_test
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"strings"
 	"testing"
@@ -81,6 +82,23 @@ func TestABundleReachesItsOwnBoundObjectsAndStreamsOnly(t *testing.T) {
 		t.Fatalf("fill %+v, %v", fill, err)
 	}
 
+	// A-42: an event said on the module's own stream lands on the binding's subject plus the event, acknowledged, and a
+	// second say with the same id is the same message.
+	said, err := conn.StreamPublish("m", buscalls.StreamPublishRequest{Stream: "events", Event: "scrub.requested",
+		Body: json.RawMessage(`{"pool":"tank"}`), ID: "id-1"})
+	if err != nil || said.Sequence != 3 {
+		t.Fatalf("said %+v, %v", said, err)
+	}
+	if again, err := conn.StreamPublish("m", buscalls.StreamPublishRequest{Stream: "events", Event: "scrub.requested",
+		Body: json.RawMessage(`{"pool":"tank"}`), ID: "id-1"}); err != nil || again.Sequence != 3 {
+		t.Fatalf("said again %+v, %v", again, err)
+	}
+	if page, err := conn.StreamRead("m", buscalls.StreamReadRequest{Stream: "events", From: 3,
+		Subjects: "mesh.state.m.events.scrub.requested"}); err != nil || len(page.Messages) != 1 ||
+		string(page.Messages[0].Body) != `{"pool":"tank"}` {
+		t.Fatalf("read back %+v, %v", page, err)
+	}
+
 	for _, c := range []struct {
 		name, module, refusal string
 		call                  func(module string) error
@@ -97,6 +115,14 @@ func TestABundleReachesItsOwnBoundObjectsAndStreamsOnly(t *testing.T) {
 			_, err := conn.ObjectsList(module, buscalls.ObjectsRequest{Objects: "events"})
 			return err
 		}},
+		{"say on another module's stream", "other", `other was bound no stream called "events"`, func(module string) error {
+			_, err := conn.StreamPublish(module, buscalls.StreamPublishRequest{Stream: "events", Event: "x"})
+			return err
+		}},
+		{"say on a binding that is not a stream", "m", `"files" is bound with the storage type object-store, not stream`, func(module string) error {
+			_, err := conn.StreamPublish(module, buscalls.StreamPublishRequest{Stream: "files", Event: "x"})
+			return err
+		}},
 		{"a work queue not bound", "m", `bound no stream called "jobs"`, func(module string) error {
 			_, err := conn.WorkQueueSize(module, buscalls.WorkQueueRequest{Queue: "jobs"})
 			return err