Enable use of json client ID credentials

Changed k8s_auth() to allow for arg 'json'. Can now provide OAuth Client ID credentials via json file.

.gitignore

@@ -3,3 +3,4 @@
 .RData
 test.R
 .httr-oauth
+secret.json

R/k8s_auth.R

@@ -2,11 +2,17 @@
 #'
 #' Calls googleAuthR to authenticate with the Google Cloud Platform
 #' @keywords k8s_auth
+#' @param json Path to your json client_secret credentials.
 #' @importFrom googleAuthR gar_auth
 #' @export
 #' @examples
 #' k8s_auth()
+#' k8s_auth(json = "client_secret.json")
 
-k8s_auth <- function() {
-  googleAuthR::gar_auth()
+k8s_auth <- function(json = NULL) {
+  if(is.null(json)) {
+    googleAuthR::gar_auth()
+  } else {
+    googleAuthR::gar_set_client(json)
+  }
 }

README.md

@@ -34,7 +34,7 @@ k8s_auth()
 
 ### Create a cluster
 ```r
-# Create a 3 node, n1-standard-1, 100Gb disk, cluster with the name 'r-cluster'
+# Create a 3 node, n1-standard-1, 100Gb disk, cluster with the default name 'r-cluster'
 # Cluster comes configured with recommended scopes https://www.googleapis.com/auth/compute and https://www.googleapis.com/auth/devstorage.read_only
 createCluster(projectId = "myProject", "europe-west1-d")
 ```