fix(slackbot): Do not hang after a dialog is cancelled

pkg/slack/README.md

@@ -0,0 +1,12 @@
+# Slackbot integration for Variant 2
+
+This package provides a HTTP server that handles Slack interaction callbacks so that
+it can run any variant command in response to a Slack slash command.
+
+## Acknowledgements
+
+I've learned how to code a Slack bot in Go by reading the following repositories and articles:
+
+- https://github.com/kpurdon/slappd
+- https://github.com/shiimaxx/slack-coffeebot
+- https://github.com/eure/cafe-bot/

pkg/slack/slack.go

@@ -259,7 +259,10 @@ func (conn *Connection) Run() error {
 
 		userInput := cmd.Command + " " + cmdText
 
-		c := "run " + cmdText
+		// This should be a full Variant command without the executable name.
+		//
+		// E.g. for what you would type `variant run foo bar --opt1`, this shuold be `run foo bar --opt1`, as without the executable name.
+		variantCmdWithArgs := "run " + cmdText
 
 		response := slack.Message{}
 		// You should always specify response type even when you're intended to use the default "ephemeral"
@@ -278,7 +281,7 @@ func (conn *Connection) Run() error {
 			_, _, _, err := conn.Client.SendMessage(
 				cmd.ChannelID,
 				slack.MsgOptionResponseURL(cmd.ResponseURL, slack.ResponseTypeEphemeral),
-				slack.MsgOptionText(fmt.Sprintf("Running `%s`... I'll soon post a message visible to everyone in this channel to share the progress and the result of it.", c), false),
+				slack.MsgOptionText(fmt.Sprintf("Running `%s`... I'll soon post a message visible to everyone in this channel to share the progress and the result of it.", variantCmdWithArgs), false),
 			)
 			if err != nil {
 				fmt.Printf("async response 1 error: %v", err)
@@ -299,7 +302,7 @@ func (conn *Connection) Run() error {
 				return
 			}
 
-			res := conn.HandleSlashCommand(conn, c, cmd)
+			res := conn.HandleSlashCommand(conn, variantCmdWithArgs, cmd)
 
 			fmt.Printf("async slash command run finished: %s\n", res)
 

slack.go

@@ -63,15 +63,22 @@ func (r *Runner) StartSlackbot(name string) error {
 
 				callbackID := message.UserID + "_" + message.TriggerID
 				dialog := slack.Dialog{
-					Title:       cmd,
-					SubmitLabel: "Run",
-					CallbackID:  callbackID,
-					Elements:    elems,
+					Title:          cmd,
+					SubmitLabel:    "Run",
+					CallbackID:     callbackID,
+					Elements:       elems,
+					NotifyOnCancel: true,
 				}
 
 				done := make(chan error, 1)
 
 				bot.RegisterInteractionCallbackHandler(callbackID, func(callback slack.InteractionCallback) (interface{}, error) {
+					if callback.Type == slack.InteractionTypeDialogCancellation {
+						done <- nil
+
+						return nil, nil
+					}
+
 					if callback.Type != slack.InteractionTypeDialogSubmission {
 						return nil, fmt.Errorf("unexpected type of interaction callback: want %s, got %s", slack.InteractionTypeDialogSubmission, callback.Type)
 					}