This is a tutorial shows how to comment on an issue, this can be useful in many cases. For example to mention ceratin persons on creating or escalations.

Steps

1. Create a new Action by clicking CREATE button
2. Enter a name: Comment issue and click CREATE
3. Select Method: POST and URL: <your_base_url>/rest/api/2/issue/{{issue.key}}/comment
   From the Atlassian REST API we can read to comment on an issue we need to call POST /rest/api/2/issue/{{issue.key}}/comment
4. Select Authentication method: Basic Auth, specify a user that has comment permission in the project
5. Add request headers, key: Content-Type with value application/json

6. On the Body section add the following

   {
       "body":"RINT says hi {{issue.assignee.displayname}}!"
   }

7. Click Triggers tab
8. Select ISSUE CREATED event
9. On JQL Condition. When to execute the event(s) write Project = TESTB and to limit the trigger to the TESTB project
10. Click SAVE
11. (Optional) Click Test button, Issue Key needs to be provided and click Send, Then go Log Tab.