Add the ability to set the log level at startup

Previously, in order to change the log level, one must exec into each
container and run a command. This is nice for existing containers, but
can be tedious if trying to run containers from the start with a log
level different from "info."

This change adds the ability to set an environment variable and start
the container with a desired log level.

Signed-off-by: Donnie Adams <donnie@acorn.io>

pkg/logserver/logserver.go

@@ -24,9 +24,14 @@ type Server struct {
 	Debug          bool
 }
 
-// StartServerWithDefaults starts the server with default values
+// StartServerWithDefaults starts the server with default values. If the ACORN_LOG_LEVEL environment variable is set,
+// it will be parsed and used to set the log level.
 func StartServerWithDefaults() {
-	logrus.SetLevel(logrus.InfoLevel)
+	if level, err := logrus.ParseLevel(os.Getenv("ACORN_LOG_LEVEL")); err == nil {
+		logrus.SetLevel(level)
+	} else {
+		logrus.SetLevel(logrus.InfoLevel)
+	}
 	s := Server{
 		SocketLocation: DefaultSocketLocation,
 	}