more metrics infrastructure (#128)

cmd/zrok/metrics.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"github.com/michaelquigley/cf"
+	"github.com/openziti/zrok/controller/metrics"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(newMetricsCommand().cmd)
+}
+
+type metricsCommand struct {
+	cmd *cobra.Command
+}
+
+func newMetricsCommand() *metricsCommand {
+	cmd := &cobra.Command{
+		Use:   "metrics <configPath>",
+		Short: "Start a zrok metrics agent",
+		Args:  cobra.ExactArgs(1),
+	}
+	command := &metricsCommand{cmd}
+	cmd.Run = command.run
+	return command
+}
+
+func (cmd *metricsCommand) run(_ *cobra.Command, args []string) {
+	cfg, err := metrics.LoadConfig(args[0])
+	if err != nil {
+		panic(err)
+	}
+	logrus.Infof(cf.Dump(cfg, metrics.GetCfOptions()))
+
+	if err := metrics.Run(cfg); err != nil {
+		panic(err)
+	}
+}

controller/metrics/config.go

@@ -1,5 +1,18 @@
 package metrics
 
+import (
+	"github.com/michaelquigley/cf"
+	"github.com/pkg/errors"
+)
+
 type Config struct {
 	Source interface{}
 }
+
+func LoadConfig(path string) (*Config, error) {
+	cfg := &Config{}
+	if err := cf.BindYaml(cfg, path, GetCfOptions()); err != nil {
+		return nil, errors.Wrapf(err, "error loading config from '%v'", path)
+	}
+	return cfg, nil
+}

controller/metrics/fileSource.go

@@ -1,17 +1,42 @@
 package metrics
 
-import "github.com/michaelquigley/cf"
+import (
+	"github.com/michaelquigley/cf"
+	"github.com/pkg/errors"
+	"os"
+)
 
 type FileSourceConfig struct {
 	Path string
 }
 
 func loadFileSourceConfig(v interface{}, opts *cf.Options) (interface{}, error) {
-	return nil, nil
+	if submap, ok := v.(map[string]interface{}); ok {
+		cfg := &FileSourceConfig{}
+		if err := cf.Bind(cfg, submap, cf.DefaultOptions()); err != nil {
+			return nil, err
+		}
+		return &fileSource{cfg}, nil
+	}
+	return nil, errors.New("invalid config structure for 'file' source")
 }
 
-type fileSource struct{}
+type fileSource struct {
+	cfg *FileSourceConfig
+}
 
 func (s *fileSource) Start() (chan struct{}, error) {
-	return nil, nil
+	f, err := os.Open(s.cfg.Path)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error opening '%v'", s.cfg.Path)
+	}
+	ch := make(chan struct{})
+	go func() {
+		f.Close()
+		close(ch)
+	}()
+	return ch, nil
+}
+
+func (s *fileSource) Stop() {
 }

etc/metrics.yml

@@ -0,0 +1,4 @@
+source:
+  type:               file
+  path:               /tmp/fabric-usage.log
+