Add json log formatter option (#116)

README.md

@@ -80,9 +80,8 @@ role. See this [StackOverflow post](http://stackoverflow.com/a/33850060) for mor
 ### kube2iam daemonset
 
 Run the kube2iam container as a daemonset (so that it runs on each worker) with `hostNetwork: true`.
-The kube2iam daemon and iptables rule (see below) need to run before all other pods that would require 
-access to AWS resources.  
-
+The kube2iam daemon and iptables rule (see below) need to run before all other pods that would require
+access to AWS resources.
 
 ```yaml
 apiVersion: extensions/v1beta1
@@ -267,7 +266,9 @@ metadata:
       ["role-arn"]
   name: default
 ```
-_Note:_ You can also use glob-based matching for namespace restrictions, which works nicely with the path-based namespacing supported for AWS IAM roles. 
+
+_Note:_ You can also use glob-based matching for namespace restrictions, which works nicely with the path-based 
+namespacing supported for AWS IAM roles. 
 
 Example: to allow all roles prefixed with `my-custom-path/` to be assumed by pods in the default namespace, the 
 default namespace would be annotated as follows:
@@ -371,12 +372,11 @@ spec:
             privileged: true
 ```
 
-
 ### Debug
 
 By using the --debug flag you can enable some extra features making debugging easier:
 
-- `/debug/store` endpoint enabled to dump knowledge of namespaces and role association.
+* `/debug/store` endpoint enabled to dump knowledge of namespaces and role association.
 
 ### Base ARN auto discovery
 
@@ -412,6 +412,7 @@ Usage of ./build/bin/darwin/kube2iam:
       --iam-role-key string                 Pod annotation key used to retrieve the IAM role (default "iam.amazonaws.com/role")
       --insecure                            Kubernetes server should be accessed without verifying the TLS. Testing only
       --iptables                            Add iptables rule (also requires --host-ip)
+      --log-format string                   Log format (text/json) (default "text")
       --log-level string                    Log level (default "info")
       --metadata-addr string                Address for the ec2 metadata (default "169.254.169.254")
       --namespace-key string                Namespace annotation key used to retrieve the IAM roles allowed (value in annotation should be json array) (default "iam.amazonaws.com/allowed-roles")
@@ -426,7 +427,7 @@ Usage of ./build/bin/darwin/kube2iam:
 * Build and push dev image to docker hub: `make docker-dev DOCKER_REPO=<your docker hub username>`
 * Update `deployment.yaml` as needed
 * Deploy to local kubernetes cluster: `kubectl create -f deployment.yaml` or
-`kubectl delete -f deployment.yaml && kubectl create -f deployment.yaml`
+  `kubectl delete -f deployment.yaml && kubectl create -f deployment.yaml`
 * Expose as service: `kubectl expose deployment kube2iam --type=NodePort`
 * Retrieve the services url: `minikube service kube2iam --url`
 * Test your changes e.g. `curl -is $(minikube service kube2iam --url)/healthz`

cmd/main.go

@@ -32,6 +32,7 @@ func addFlags(s *server.Server, fs *pflag.FlagSet) {
 	fs.StringVar(&s.HostIP, "host-ip", s.HostIP, "IP address of host")
 	fs.DurationVar(&s.BackoffMaxInterval, "backoff-max-interval", s.BackoffMaxInterval, "Max interval for backoff when querying for role.")
 	fs.DurationVar(&s.BackoffMaxElapsedTime, "backoff-max-elapsed-time", s.BackoffMaxElapsedTime, "Max elapsed time for backoff when querying for role.")
+	fs.StringVar(&s.LogFormat, "log-format", s.LogFormat, "Log format (text/json)")
 	fs.StringVar(&s.LogLevel, "log-level", s.LogLevel, "Log level")
 	fs.BoolVar(&s.Verbose, "verbose", false, "Verbose")
 	fs.BoolVar(&s.Version, "version", false, "Print the version and exits")
@@ -53,6 +54,10 @@ func main() {
 		log.SetLevel(logLevel)
 	}
 
+	if strings.ToLower(s.LogFormat) == "json" {
+		log.SetFormatter(&log.JSONFormatter{})
+	}
+
 	if s.Version {
 		version.PrintVersionAndExit()
 	}

server/server.go

@@ -28,6 +28,7 @@ const (
 	defaultCacheSyncAttempts = 10
 	defaultIAMRoleKey        = "iam.amazonaws.com/role"
 	defaultLogLevel          = "info"
+	defaultLogFormat         = "text"
 	defaultMaxElapsedTime    = 2 * time.Second
 	defaultMaxInterval       = 1 * time.Second
 	defaultMetadataAddress   = "169.254.169.254"
@@ -48,6 +49,7 @@ type Server struct {
 	HostIP                  string
 	NamespaceKey            string
 	LogLevel                string
+	LogFormat               string
 	AddIPTablesRule         bool
 	AutoDiscoverBaseArn     bool
 	AutoDiscoverDefaultRole bool
@@ -308,6 +310,7 @@ func NewServer() *Server {
 		IAMRoleKey:            defaultIAMRoleKey,
 		BackoffMaxInterval:    defaultMaxInterval,
 		LogLevel:              defaultLogLevel,
+		LogFormat:             defaultLogFormat,
 		MetadataAddress:       defaultMetadataAddress,
 		NamespaceKey:          defaultNamespaceKey,
 	}