From 2de4e5af7b7dd5a699ffd2b8f4c00f2414494a79 Mon Sep 17 00:00:00 2001
From: Brian Goff <cpuguy83@gmail.com>
Date: Wed, 31 Oct 2018 14:26:32 -0700
Subject: [PATCH] Add ocagent exporter

ocagent allows users to send traces out of VK to a "standard"  external forwarder
(standard as in this is a format/protocol defined in the opencensus project).

This allows uers to implement metrics for whatever backend they want
without having to add it into VK directly.
---
 census_ocagent.go | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 census_ocagent.go

diff --git a/census_ocagent.go b/census_ocagent.go
new file mode 100644
index 0000000..6ad1558
--- /dev/null
+++ b/census_ocagent.go
@@ -0,0 +1,37 @@
+// +build !no_ocagent_exporter
+
+package cmd
+
+import (
+	"os"
+
+	"contrib.go.opencensus.io/exporter/ocagent"
+	"github.com/cpuguy83/strongerrors"
+	"github.com/pkg/errors"
+	"go.opencensus.io/trace"
+)
+
+func init() {
+	RegisterTracingExporter("ocagent", NewOCAgentExporter)
+}
+
+// NewOCAgentExporter creates a new opencensus tracing exporter using the opencensus agent forwarder.
+func NewOCAgentExporter(opts TracingExporterOptions) (trace.Exporter, error) {
+	agentOpts := append([]ocagent.ExporterOption{}, ocagent.WithServiceName(opts.ServiceName))
+
+	if endpoint := os.Getenv("OCAGENT_ENDPOINT"); endpoint != "" {
+		agentOpts = append(agentOpts, ocagent.WithAddress(endpoint))
+	} else {
+		return nil, strongerrors.InvalidArgument(errors.New("must set endpoint address in OCAGENT_ENDPOINT"))
+	}
+
+	switch os.Getenv("OCAGENT_INSECURE") {
+	case "0", "no", "n", "off", "":
+	case "1", "yes", "y", "on":
+		agentOpts = append(agentOpts, ocagent.WithInsecure())
+	default:
+		return nil, strongerrors.InvalidArgument(errors.New("invalid value for OCAGENT_INSECURE"))
+	}
+
+	return ocagent.NewExporter(agentOpts...)
+}