There have been multiple issues with making Helm happy with Grafana 7, and the following affects the reports functionality in OpenNMS.
OpenNMS has a feature to generate PDF reports from Grafana Dashboards. With the current state of the Docker images for Helm 5.0.3 (based on Grafana 6.7.x), the reports are generated without issues.
However, with Grafana 7.x and Helm 6.x, the reports are not rendered if I use the Docker image. The Grafana log says I have to install the image renderer plugin, but if I do that I get the following error and some unexpected HTML exceptions in the generated PDF report:
Clearly, there is a missing library not available in the Docker Image for Grafana (which we use as the base image for Helm in its Dockerfile) that must be installed to use the Image Renderer.
For now, the workaround is to avoid Docker, but as there are still other rendering issues, it is recommended to stay with Grafana 6.7.2 and Helm 5.0.3 for now.