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I'm working a lot with GDAL VRT raster layers in QGIS 3.14, often changing the file content while viewing the rasters in map canvas. When I zoom or refresh the canvas in QGIS 2.18, all modified VRT raster layers are refreshed as well. In QGIS 3.14 it looks like VRT layers are cached. I can refresh the virtual raster layers only with the help of the indispensible "changeDataSource" plugin.
What do I need to refresh a VRT layer with Python?
The only possible method I found to solve this problem is to write the Layer XML to a DOM document and reread it afterwards. I grabbed this idea from "changeDataSource" plugin.
from qgis.PyQt.QtXml import QDomDocument
from qgis.core import QgsReadWriteContext
...
XMLDocument = QDomDocument("style")
XMLMapLayers = XMLDocument.createElement("maplayers")
XMLMapLayer = XMLDocument.createElement("maplayer")
context = QgsReadWriteContext()
layer.writeLayerXml(XMLMapLayer,XMLDocument, context)
layer.readLayerXml(XMLMapLayer, context)
layer.reload()
iface.actionDraw().trigger()
iface.mapCanvas().refresh()