Make `func invoke` print any response it receives. (#881)

* Make `func invoke` print any response it receives.

Signed-off-by: Lance Ball <lball@redhat.com>

* fixup: improve test

Signed-off-by: Lance Ball <lball@redhat.com>

* fixup: check Write() return value

Signed-off-by: Lance Ball <lball@redhat.com>

client.go

@@ -846,7 +846,7 @@ func (c *Client) Remove(ctx context.Context, cfg Function, deleteAll bool) error
 // See NewInvokeMessage for its defaults.
 // Functions are invoked in a manner consistent with the settings defined in
 // their metadata.  For example HTTP vs CloudEvent
-func (c *Client) Invoke(ctx context.Context, root string, target string, m InvokeMessage) (err error) {
+func (c *Client) Invoke(ctx context.Context, root string, target string, m InvokeMessage) (s string, err error) {
 	go func() {
 		<-ctx.Done()
 		c.progressListener.Stopping()

client_test.go

@@ -1099,6 +1099,10 @@ func TestClient_Invoke_HTTP(t *testing.T) {
 		if req.Form.Get("ID") != message.ID {
 			t.Fatalf("expected message ID '%v', got '%v'", message.ID, req.Form.Get("ID"))
 		}
+		_, err := res.Write([]byte("hello world"))
+		if err != nil {
+			t.Fatal(err)
+		}
 	})
 
 	// Expose the masquarading Function on an OS-chosen port.
@@ -1139,10 +1143,16 @@ func TestClient_Invoke_HTTP(t *testing.T) {
 	defer job.Stop()
 
 	// Invoke the Function, which will use the mock Runner
-	if err := client.Invoke(context.Background(), f.Root, "", message); err != nil {
+	r, err := client.Invoke(context.Background(), f.Root, "", message)
+	if err != nil {
 		t.Fatal(err)
 	}
 
+	// Check the response value
+	if r != "hello world" {
+		t.Fatal("Unexpected response from function " + r)
+	}
+
 	// Fail if the Function was never invoked.
 	if !invoked {
 		t.Fatal("Function was not invoked")
@@ -1166,15 +1176,18 @@ func TestClient_Invoke_CloudEvent(t *testing.T) {
 		invoked bool // flag the Function was invoked
 		ctx     = context.Background()
 		message = fn.NewInvokeMessage() // message to send to the Function
+		evt     *cloudevents.Event      // A pointer to the received event
 	)
 
 	// A CloudEvent Receiver which masquarades as a running Function and
 	// verifies the invoker sent the message as a populated CloudEvent.
-	receiver := func(ctx context.Context, event cloudevents.Event) {
+	receiver := func(ctx context.Context, event cloudevents.Event) *cloudevents.Event {
 		invoked = true
 		if event.ID() != message.ID {
 			t.Fatalf("expected event ID '%v', got '%v'", message.ID, event.ID())
 		}
+		evt = &event
+		return evt
 	}
 
 	// A cloudevent receive handler which will expect the HTTP protocol
@@ -1224,10 +1237,14 @@ func TestClient_Invoke_CloudEvent(t *testing.T) {
 	defer job.Stop()
 
 	// Invoke the Function, which will use the mock Runner
-	if err := client.Invoke(context.Background(), f.Root, "", message); err != nil {
+	r, err := client.Invoke(context.Background(), f.Root, "", message)
+	if err != nil {
 		t.Fatal(err)
 	}
-
+	// Test the contents of the returned string.
+	if r != evt.String() {
+		t.Fatal("Invoke failed to return a response")
+	}
 	// Fail if the Function was never invoked.
 	if !invoked {
 		t.Fatal("Function was not invoked")

cmd/invoke.go

@@ -160,12 +160,12 @@ func runInvoke(cmd *cobra.Command, args []string, newClient ClientFactory) (err
 	}
 
 	// Invoke
-	err = client.Invoke(cmd.Context(), cfg.Path, cfg.Target, m)
+	s, err := client.Invoke(cmd.Context(), cfg.Path, cfg.Target, m)
 	if err != nil {
 		return err
 	}
 
-	fmt.Fprintf(cmd.OutOrStderr(), "Invoked %v\n", cfg.Target)
+	fmt.Fprintln(cmd.OutOrStderr(), s)
 	return
 }
 

invoke.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
 	"time"
@@ -45,13 +46,13 @@ func NewInvokeMessage() InvokeMessage {
 
 // invoke the Function instance in the target environment with the
 // invocation message.
-func invoke(ctx context.Context, c *Client, f Function, target string, m InvokeMessage) error {
+func invoke(ctx context.Context, c *Client, f Function, target string, m InvokeMessage) (string, error) {
 
 	// Get the first available route from 'local', 'remote', a named environment
 	// or treat target
 	route, err := invocationRoute(ctx, c, f, target) // choose instance to invoke
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	// Format" either 'http' or 'cloudevent'
@@ -75,7 +76,7 @@ func invoke(ctx context.Context, c *Client, f Function, target string, m InvokeM
 	case "cloudevent":
 		return sendEvent(ctx, route, m, c.transport)
 	default:
-		return fmt.Errorf("format '%v' not supported.", format)
+		return "", fmt.Errorf("format '%v' not supported.", format)
 	}
 }
 
@@ -130,7 +131,7 @@ func invocationRoute(ctx context.Context, c *Client, f Function, target string)
 }
 
 // sendEvent to the route populated with data in the invoke message.
-func sendEvent(ctx context.Context, route string, m InvokeMessage, t http.RoundTripper) (err error) {
+func sendEvent(ctx context.Context, route string, m InvokeMessage, t http.RoundTripper) (resp string, err error) {
 	event := cloudevents.NewEvent()
 	event.SetID(m.ID)
 	event.SetSource(m.Source)
@@ -146,15 +147,18 @@ func sendEvent(ctx context.Context, route string, m InvokeMessage, t http.RoundT
 		return
 	}
 
-	result := c.Send(cloudevents.ContextWithTarget(ctx, route), event)
+	evt, result := c.Request(cloudevents.ContextWithTarget(ctx, route), event)
 	if cloudevents.IsUndelivered(result) {
 		err = fmt.Errorf("unable to invoke: %v", result)
+	} else if evt != nil { // Check for nil in case no event is returned
+		resp = evt.String()
 	}
+
 	return
 }
 
 // sendPost to the route populated with data in the invoke message.
-func sendPost(ctx context.Context, route string, m InvokeMessage, t http.RoundTripper) error {
+func sendPost(ctx context.Context, route string, m InvokeMessage, t http.RoundTripper) (string, error) {
 	client := http.Client{
 		Transport: t,
 		Timeout:   10 * time.Second,
@@ -167,11 +171,12 @@ func sendPost(ctx context.Context, route string, m InvokeMessage, t http.RoundTr
 		"Data":        {m.Data},
 	})
 	if err != nil {
-		return err
+		return "", err
 	}
 	defer resp.Body.Close()
-	if resp.StatusCode != 200 {
+	if resp.StatusCode > 299 {
-		return fmt.Errorf("failure invoking '%v' (HTTP %v)", route, resp.StatusCode)
+		return "", fmt.Errorf("failure invoking '%v' (HTTP %v)", route, resp.StatusCode)
 	}
-	return nil
+	b, err := io.ReadAll(resp.Body)
+	return string(b), err
 }