Support setting the hostname of the agent via environment variable. (#54

)

* Support setting the hostname of the agent via environment variable.

* Apply the same logic for the port

agent.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"strconv"
 	"time"
 )
@@ -57,13 +58,18 @@ func (r *agentS) makeURL(prefix string) string {
 }
 
 func (r *agentS) makeHostURL(host string, prefix string) string {
-	var port int
-	if r.sensor.options.AgentPort == 0 {
-		port = agentDefaultPort
-	} else {
-		port = r.sensor.options.AgentPort
+	envPort := os.Getenv("INSTANA_AGENT_PORT")
+	port := agentDefaultPort
+	if r.sensor.options.AgentPort > 0 {
+		return r.makeFullURL(host, r.sensor.options.AgentPort, prefix)
+	}
+	if envPort == "" {
+		return r.makeFullURL(host, port, prefix)
+	}
+	port, err := strconv.Atoi(envPort)
+	if err != nil {
+		return r.makeFullURL(host, agentDefaultPort, prefix)
 	}
-
 	return r.makeFullURL(host, port, prefix)
 }
 

fsm.go

@@ -80,11 +80,16 @@ func (r *fsmS) lookupAgentHost(e *f.Event) {
 			}
 		}
 	}
-
-	if r.agent.sensor.options.AgentHost != "" {
-		go r.checkHost(r.agent.sensor.options.AgentHost, cb)
-	} else {
-		go r.checkHost(agentDefaultHost, cb)
+	hostNames := []string{
+		r.agent.sensor.options.AgentHost,
+		os.Getenv("INSTANA_AGENT_HOST"),
+		agentDefaultHost,
+	}
+	for _, name := range hostNames {
+		if name != "" {
+			go r.checkHost(name, cb)
+			return
+		}
 	}
 }