Hello I would like to enquire if there is an API that can be used to retrieve Ganglia stats for all clients from a single ganglia server?
Answer
The Ganglia gmetad component listens on ports 8651 and 8652 by default and replies with XML metric data. The XML data type definition can be seen on GitHub here.
Gmetad needs to be configured to allow XML replies to be sent to specific hosts or all hosts. By default only localhost is allowed. This can be changed in /etc/ganglia/gmetad.conf.
Connecting to port 8651 will get you a default XML report of all metrics as a response.
Port 8652 is the interactive port which allows for customized queries. Gmetad will recognize raw text queries sent to this port, i.e. not HTTP requests.
Here are examples of some queries:
/?filter=summary(returns a summary of the whole grid, i.e. all clusters)/clusterName(returns raw data of a cluster called "clusterName")/clusterName/hostName(returns raw data for host "hostName" in cluster "clusterName")/clusterName?filter=summary(returns a summary of only cluster "clusterName")
The ?filter=summary parameter changes the output to contain the sum of each metric value over all hosts. The number of hosts is also provided for each metric so that the mean value may be calculated.