Thank you so much @AndreyBelym, that was exactly what I needed! I do have one other related question. I want to add the Slack reporter, which I have installed locally and it works great! Where do I put the required variables for that?
I put the browserstack plugin ones in the buildspec.yml, and they are working, but when I add the slack ones, they don't work as expected. In the AWS CodeBuild console it appears as though it is working correctly. I see the messages such as "The following message is send to slack: ..." but I never actually receive the slack notifications.