How can I verify that my buildah container image was actually created in my Tekton Task
So is there any good way to verify that my container image was actually created?
You seem to have created a custom Buildah-task. I would recommend to use the Buildah-task from Tekton Catalog, or at least use it as inspiration.
The Buildah-task in the catalog use a digestfile that is written by buildah when pushed (I guess you want to push it so that you can deploy it?) and then the Task has a Task Result that returns the image digest - if any step fails that step is shown as failed and you can see it in e.g. a Dashboard or using the cli client.