nginxdbg.go

package nginxdbg

import (
	"bufio"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/intelsdi-x/snap/control/plugin"
	"github.com/intelsdi-x/snap/control/plugin/cpolicy"
	"github.com/intelsdi-x/snap/core"
)

const (
	// Name of plugin
	Name = "nginxdbg"
	// Version of plugin
	Version = 1
	// Type of plugin
	Type = plugin.CollectorPluginType
)

type Nginxdbg struct{}

func (n *Nginxdbg) CollectMetrics(inmts []plugin.MetricType) (mts []plugin.MetricType, err error) {
	return nil, nil
}

func (n *Nginxdbg) GetMetricTypes(cfg plugin.ConfigType) ([]plugin.MetricType, error) {

	mts := []plugin.MetricType{}
	for i := 0; i < 900; i++ {
		tmp := plugin.MetricType{}

		ss := strings.Split("/staples/nginx/stream/upstreams/dns_udp_backends/peers/host_id_745cd_eurxserver_com__12kc135_americanid_int/health_checks/checks", "/")
		tmp.Namespace_ = core.NewNamespace(ss...)

		mts = append(mts, tmp)

		// fmt.Println("Obj =", i, " mts =", mts) // I don't think you really want to print mts here.
		// if you do it will eventually exceed the scanners buffer that's reading stdout and will break
		// the plugin.
		fmt.Printf("i: %v metric: %+v \n", i, tmp)
	}

	f := bufio.NewWriter(os.Stdout)
	defer f.Flush()

	// fmt.Println("len =", len(mts), " Capcity =", cap(mts))
	fmt.Fprintf(f, "len=%v cap=%v\n", len(mts), cap(mts))

	//The Below println is not print the data when run along with the agent. But works with stand alone
	// nb, err := fmt.Fprintf(f, "GetMetricTypes = %+v \n", mts)

	// I'm leaving the above line commented out since it won't work.  Snapd uses standard out to communicate
	// information about the plugin with control.  After this handshake we then capture stdout (and stderr)
	// and in the v0.14 which you downloaded wrote <plugin>.stdout and <plugin>.stderr files using a
	// routine that scans the stdout.  The problem that this line runs into is the fact that we are scaning
	// using new lines as the token and the line above is huge and exceeds the buffer.

	// From the bufio.Scanner docs: Scanning stops unrecoverably at EOF, the first I/O error, or a token too
	// large to fit in the buffer. When a scan stops, the reader may have advanced arbitrarily far past the
	// last token.

	// At this point the best advice I can give is to not print "large" items to stdout and instead open a
	// file that the plugin can write to.  In the meantime we'll open an issue and see if there isn't a
	// clever solution we can put into place or provide more effective guidance.

	// P.S. Note all of the newlines added to the print statements.  These are critical since we are scanning
	// stdout looking for them before printing.

	return mts, nil
}

func (n *Nginxdbg) GetConfigPolicy() (*cpolicy.ConfigPolicy, error) {
	cfg := cpolicy.New()
	policy := cpolicy.NewPolicyNode()
	cfg.Add([]string{"staples", "nginxdbg"}, policy)
	return cfg, nil
}

func Meta() *plugin.PluginMeta {
	return plugin.NewPluginMeta(
		Name,
		Version,
		Type,
		[]string{plugin.SnapGOBContentType},
		[]string{plugin.SnapGOBContentType},
		plugin.Unsecure(true),
		plugin.RoutingStrategy(plugin.DefaultRouting),
		plugin.CacheTTL(1100*time.Millisecond),
	)
}