Update readme on stdout support

README.md

@@ -315,9 +315,10 @@ Type: String
 
 Default: `/var/log/aws-routed-eni/plugin.log`
 
-Valid Values: `stdout` or a file path
+Valid Values: `stderr` or a file path
 
-Specifies where to write the logging output for `aws-cni` plugin. Either to stdout or to override the default file (i.e., `/var/log/aws-routed-eni/plugin.log`).
+Specifies where to write the logging output for `aws-cni` plugin. Either to `stderr` or to override the default file (i.e., `/var/log/aws-routed-eni/plugin.log`).
+`Stdout` cannot be supported for plugin log, please refer to #1248 for more details.
 
 ---
 

pkg/awsutils/awsutils.go

@@ -1044,6 +1044,9 @@ func (cache *EC2InstanceMetadataCache) DescribeAllENIs() (DescribeAllENIsResult,
 		eniID := aws.StringValue(ec2res.NetworkInterfaceId)
 		eniMetadata := eniMap[eniID]
 		interfaceType := aws.StringValue(ec2res.InterfaceType)
+
+		log.Infof("%s is of type: %s", eniID, interfaceType)
+
 		// This assumes we only have one trunk attached to the node..
 		if interfaceType == "trunk" {
 			trunkENI = eniID

scripts/entrypoint.sh

@@ -35,6 +35,15 @@ log_in_json()
     printf '{"level":"%s","ts":"%s","caller":"%s","msg":"%s"}\n' "$LOGTYPE" "$TIMESTAMP" "$FILENAME" "$MSG"
 }
 
+validate_env_var()
+{
+    log_in_json info "Validating env variables ..."
+    if [[ "${AWS_VPC_K8S_PLUGIN_LOG_FILE,,}" == "stdout" ]]; then
+        log_in_json error "AWS_VPC_K8S_PLUGIN_LOG_FILE cannot be set to stdout"
+        exit 1     
+    fi 
+}
+
 # Check for all the required binaries before we go forward
 if [ ! -f aws-k8s-agent ]; then
     log_in_json error "Required aws-k8s-agent executable not found."
@@ -55,6 +64,8 @@ AWS_VPC_K8S_PLUGIN_LOG_LEVEL=${AWS_VPC_K8S_PLUGIN_LOG_LEVEL:-"Debug"}
 
 AWS_VPC_K8S_CNI_CONFIGURE_RPFILTER=${AWS_VPC_K8S_CNI_CONFIGURE_RPFILTER:-"true"}
 
+validate_env_var
+
 # Check for ipamd connectivity on localhost port 50051
 wait_for_ipam() {
     while :