Troubleshooting

Common Problems

HTTP Error 502: Bad Gateway, please check the datasource and pmproxy settings

When I try to add a data source in Grafana, I get the following error: “HTTP Error 502: Bad Gateway, please check the datasource and pmproxy settings. To use this data source, please configure the URL in the query editor.”

check if pmproxy is running: systemctl status pmproxy
make sure that pmproxy was built with time-series (libuv) support enabled. You can verify that by reading the logfile in /var/log/pcp/pmproxy/pmproxy.log

PCP Valkey

Grafana doesn’t show any data

Make sure that pmlogger is up and running, and writing archives to the disk (/var/log/pcp/pmlogger/<host>/*)
Verify that pmproxy is running, time series support is enabled and a connection to Valkey is established: check the logfile at /var/log/pcp/pmproxy/pmproxy.log and make sure that it contains the following text: Info: Valkey slots, command keys, schema version setup
Check if the Valkey database contains any keys: valkey-cli dbsize
Check if any PCP metrics are in the Valkey database: pmseries disk.dev.read
Check if PCP metric values are in the Valkey database: pmseries 'disk.dev.read[count:10]'
Check the Grafana logs: journalctl -e -u grafana-server