Make log level configurable

Makefile

@@ -29,6 +29,7 @@ plugin: plugin/rootfs config.json
 create: plugin
 	docker plugin rm -f $(PLUGIN_NAME):$(PLUGIN_TAG) || true
 	docker plugin create $(PLUGIN_NAME):$(PLUGIN_TAG) $<
+	docker plugin set $(PLUGIN_NAME):$(PLUGIN_TAG) LOG_LEVEL=trace
 
 enable: plugin
 	docker plugin enable $(PLUGIN_NAME):$(PLUGIN_TAG)

cmd/net-dhcp/main.go

@@ -12,7 +12,7 @@ import (
 )
 
 var (
-	logLevel = flag.String("log", "info", "log level")
+	logLevel = flag.String("log", "", "log level")
 	logFile  = flag.String("logfile", "", "log file")
 	bindSock = flag.String("sock", "/run/docker/plugins/net-dhcp.sock", "bind unix socket")
 )
@@ -20,6 +20,12 @@ var (
 func main() {
 	flag.Parse()
 
+	if *logLevel == "" {
+		if *logLevel = os.Getenv("LOG_LEVEL"); *logLevel == "" {
+			*logLevel = "info"
+		}
+	}
+
 	level, err := log.ParseLevel(*logLevel)
 	if err != nil {
 		log.WithError(err).Fatal("Failed to parse log level")

config.json

@@ -6,7 +6,17 @@
             "docker.networkdriver/1.0"
         ]
     },
-    "entrypoint": ["/usr/sbin/net-dhcp", "-log", "trace", "-logfile", "/var/log/net-dhcp.log"],
+    "entrypoint": ["/usr/sbin/net-dhcp", "-logfile", "/var/log/net-dhcp.log"],
+    "env": [
+        {
+            "description": "Log level",
+            "name": "LOG_LEVEL",
+            "value": "info",
+            "settable": [
+                "value"
+            ]
+        }
+    ],
     "workdir": "/",
     "network": {
         "type": "host"
@@ -21,13 +31,9 @@
             ]
         }
     ],
-    "pidhost": false,
     "linux": {
         "capabilities": [
-            "CAP_NET_ADMIN",
-            "CAP_SYS_ADMIN",
-            "CAP_SYS_PTRACE",
-            "CAP_SYS_RESOURCE"
+            "CAP_NET_ADMIN"
         ]
     }
 }