A small go package that provides basic access to Ganglia network metrics.
Currently this package only permits decoding of Ganglia XDR packets/streams as the immediate need was for decode only rather than encode. However, I fully intend to add an encoder in the near future.
This package requires cgo and an installed libganglia (probably at least version 3.4.0).
The package uses pkg-config however ganglia does not. To get around this a
make-pkgconfig.sh script has been supplied. To use:
$ ./make-pkgconfig.sh > ganglia.pc
# assuming all went well
$ export PKG_CONFIG_PATH=`pwd`
$ go install
This package provides three main components, only one of which is technically required for basic metric decode functionality:
- An xdr decoder service started via
StartXDRDecoderand stopped viaStopXDRDecoder. - A metadata service which can collect parsed metadata packets from gmond
and auto-associate metrics with metadata (once the metadata has been seen).
This service is started automatically when the first metadata request
or registration is perfomed. See
MetadataServer.LookupandMetadataService.Register. - A simple udp network client that can stream received packets to the xdr decoder. This is provided as more of an example and will likely be replaced by something application-specific.
include main
import (
"github.com/jsipprell/ganglia"
"time"
"log"
"os"
)
func main() {
// create the main byte stream packet channel
c := make(chan []byte,1)
// the message channel to feed us decoded ganglia messages
msgchan := make(chan ganglia.Message)
go func() {
defer func() {
err := recover()
if err != nil {
log.Fatalf("PANIC: %v",err)
}
}()
t := time.Tick(5e9)
for {
select {
case now := <-t:
log.Printf("TICK: %v",now)
case msg := <-msgchan:
if msg.IsMetadataDef() {
md := msg.GetMetadata()
_,err := ganglia.MetadataServer.Register(md)
if err != nil {
log.Printf("metadata server error on %v: %v",md,err)
}
} else {
log.Println(msg.String())
}
}
}
}()
err := ganglia.StartXDRDecoder(c,nil,msgchan)
if err != nil {
log.Fatalf("cannot start xdr decoder: %v",err)
}
args := os.Args[1:]
if len(args) < 1 {
log.Fatalf("must specific network:port")
}
var mcast bool
if len(args) > 1 && args[0] == "mcast" {
args = args[1:]
mcast = true
}
// This starts the client and will send packets to:
// c -> xdr decoder -> above goroutine
ganglia.Client(args[0],mcast,c)
}