The easiest way to install plugins is by using the CLI tool grafana-cli which is bundled with grafana. Before any modification take place after modifying plugins, grafana-server needs to be restarted.
On Linux systems the grafana-cli will assume that the grafana plugin directory is `/var/lib/grafana/plugins`. It's possible to override the directory which grafana-cli will operate on by specifying the --pluginsDir flag. On Windows systems this parameter have to be specified for every call.
To manually install a Plugin via the Grafana.com API:
1. Find the plugin you want to download, the plugin id can be found on the Installation Tab on the plugin's page on Grafana.com. In this example, the plugin id is `jdbranham-diagram-panel`:
2. Use the Grafana API to find the plugin using this url `https://grafana.com/api/plugins/<plugin id from step 1>`. For example: https://grafana.com/api/plugins/jdbranham-diagram-panel should return:
4. Download the plugin with `https://grafana.com/api/plugins/<plugin id from step 1>/versions/<current version>/download` (for example: https://grafana.com/api/plugins/jdbranham-diagram-panel/versions/1.4.0/download). Unzip the downloaded file into the Grafana Server's `plugins` directory.