To add a draw.io diagram, navigate to the issue page then on the "more" toolbar button select "Add drawio diagram"
Note that the user must have the appropriate JIRA permissions with attachments to open or edit them.
This will bring up the diagram editor. Edit your diagram, using the save button in the top right when you wish to write over the diagram attachment.
Pressing the exit button in the top right will exit back the JIRA issue page. The issue page will show the diagram in the attachments section as a raster image and an interactive vector version of the diagram on the right hand side panel:
The viewer on the right side can be click/touch dragged to pan. The buttons in the bottom left corner perform the following functions.
Edit the diagram
Remove the diagram from the issue
Zoom the diagram to its actual size
Zoom the diagram to fit the reader
Zoom out one level
Zooms in one level
Display the expanded in-page viewer
Basic draw.io functions