loader: load configuration from external configuration file

conf/mig-loader.cfg.inc

@@ -0,0 +1,39 @@
+; Sample MIG Loader configuration file
+
+[loader]
+    ; location of the mig api
+    api             = "http://localhost:1664/api/v1/"
+
+    ; comma delimited list of host:port proxies to use, if desired
+    ; the loader will attempt to try to proxies for manifest retrieval
+    ; proxies          = "proxy1:8888,proxy2:8888"
+
+    ; attempt to retrieve the public IP behind which the loader is running
+    discoverpublicip = off
+
+    ; attempt to retrieve AWS metadata from the metadata service to include in the environment
+    ; sent to the API
+    discoverawsmeta = off
+
+    ; the number of signatures required in a manifest for the manifest to be considered
+    ; valid
+    requiredsignatures = 1
+
+    ; Tags can be specified for a given loader at compile-time using the loader built-in
+    ; configuration TAGS value. Additional tags can be included in the configuration file
+    ; here if desired to override or extend the tags the loader has already been compiled
+    ; with.
+    ; tags = "tagname:tagvalue"
+
+[logging]
+    mode    = "stdout" ; stdout | file | syslog
+    level   = "debug"
+
+; for file logging
+;   file = "mig_scheduler.log"
+;   maxfilesize = 0 ; if > 0, log file will be rotated once it reaches size
+
+; for syslog, logs go into local3
+;    host   = "localhost"
+;    port   = 514
+;    protocol = "udp"

mig-loader/loader.go

@@ -391,13 +391,7 @@ func initContext() (err error) {
 		}
 	}()
 
-	ctx.Channels.Log = make(chan mig.Log, 37)
-	ctx.Logging, err = getLoggingConf()
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "%v\n", err)
-		os.Exit(1)
-	}
-	ctx.Logging, err = mig.InitLogger(ctx.Logging, "mig-loader")
+	ctx.Logging, err = mig.InitLogger(LOGGINGCONF, "mig-loader")
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "%v\n", err)
 		os.Exit(1)
@@ -406,8 +400,6 @@ func initContext() (err error) {
 	go func() {
 		var stop bool
 		for event := range ctx.Channels.Log {
-			// Also write the message to stderr to ease debugging
-			fmt.Fprintf(os.Stderr, "%v\n", event.Desc)
 			stop, err = mig.ProcessLog(ctx.Logging, event)
 			if err != nil {
 				panic("unable to process log")
@@ -538,16 +530,27 @@ func main() {
 	var (
 		initialMode bool
 		runService  bool
+		confPath    string
 		checkOnly   bool
 		err         error
 	)
 	runtime.GOMAXPROCS(1)
 
 	flag.BoolVar(&checkOnly, "c", false, "only check if agent is running")
+	flag.StringVar(&confPath, "f", configDefault(), "Load configuration from file")
 	flag.BoolVar(&initialMode, "i", false, "initialization mode")
 	flag.BoolVar(&runService, "s", false, "persistent service mode")
 	flag.Parse()
 
+	ctx.Channels.Log = make(chan mig.Log, 37)
+
+	err = configLoad(confPath)
+	if err != nil {
+		logInfo("warning: unable to load configuration from %v, using built-in configuration", confPath)
+	} else {
+		logInfo("using external configuration from %v", confPath)
+	}
+
 	if runService {
 		err = serviceMode()
 		if err != nil {