Show number of messages sent each hour, in bars

This seems like it should be really trivial but I have a counter metric my_messages_total. I would like to show a bar chart where each bar is 1 hours wide and shows how much the metric has increased in that hour. I can’t seem to figure out the proper way to do this. I had wondered about delta() but the docs say this is only for gauges and when I’ve tried setting min-step to 1h, my bars are not the full hour wide.

I just want to count the number of messages in each 1h ‘bucket’, can anyone give me an example?