support configuring misc http headers for Graphite requests

cmd/bosun/conf/conf.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"log"
 	"net"
+	"net/http"
 	"net/mail"
 	"net/url"
 	"os"
@@ -59,6 +60,7 @@ type Conf struct {
 
 	TSDBHost             string                    // OpenTSDB relay and query destination: ny-devtsdb04:4242
 	GraphiteHost         string                    // Graphite query host: foo.bar.baz
+	GraphiteHeaders      []string                  // extra http headers when querying graphite.
 	LogstashElasticHosts expr.LogstashElasticHosts // CSV Elastic Hosts (All part of the same cluster) that stores logstash documents, i.e http://ny-elastic01:9200
 
 	tree            *parse.Tree
@@ -84,6 +86,17 @@ func (c *Conf) GraphiteContext() graphite.Context {
 	if c.GraphiteHost == "" {
 		return nil
 	}
+	if len(c.GraphiteHeaders) > 0 {
+		headers := http.Header(make(map[string][]string))
+		for _, s := range c.GraphiteHeaders {
+			kv := strings.Split(s, ":")
+			headers.Add(kv[0], kv[1])
+		}
+		return graphite.HostHeader{
+			Host:   c.GraphiteHost,
+			Header: headers,
+		}
+	}
 	return graphite.Host(c.GraphiteHost)
 }
 
@@ -391,6 +404,11 @@ func (c *Conf) loadGlobal(p *parse.PairNode) {
 		c.TSDBHost = v
 	case "graphiteHost":
 		c.GraphiteHost = v
+	case "graphiteHeader":
+		if !strings.Contains(v, ":") {
+			c.errorf("graphiteHeader must be in key:value form")
+		}
+		c.GraphiteHeaders = append(c.GraphiteHeaders, v)
 	case "logstashElasticHosts":
 		c.LogstashElasticHosts = strings.Split(v, ",")
 	case "httpListen":

docs/configuration.md

@@ -44,6 +44,7 @@ Every variable is optional, though you should enable at least 1 backend.
   * The items page.
   * The graph page's tag list.
 * graphiteHost: an ip, hostname, ip:port, hostname:port or a URL, defaults to standard http/https ports, defaults to "/render" path.  Any non-zero path (even "/" overrides path)
+* graphiteHeader: a http header to be sent to graphite on each request in 'key:value' format. optional. can be specified multiple times.
 * logstashElasticHost: Elasticsearch host populated by logstash. Same format as tsdbHost.
 
 #### settings