Simplify lookup command (#98)

* Exact match if there is only 1 argument
* If no argument provided - match all

README.md

@@ -159,15 +159,21 @@ Examples:
 
 ```shell script
 # Search All Service Accounts
-rbac-tool lookup -e '.*'
+rbac-tool lookup
 ```
 
 ```shell script
-# Search All Service Accounts That Contains myname
+# Search Service Accounts that match myname exactly
+rbac-tool lookup myname
+```
+
+```shell script
+# Search All Service Accounts that contain myname
 rbac-tool lookup -e '.*myname.*'
 ```
 
 ```shell script
+# Lookup System Accounts (all accounts that start with system: )
 rbac-tool lookup -e '^system:'
   SUBJECT                                         | SUBJECT TYPE | SCOPE       | NAMESPACE   | ROLE                                                                 | BINDING
 +-------------------------------------------------+--------------+-------------+-------------+----------------------------------------------------------------------+---------------------------------------------------+

cmd/lookup_cmd.go

@@ -30,7 +30,10 @@ A Kubernetes RBAC lookup of Roles/ClusterRoles used by a given User/ServiceAccou
 Examples:
 
 # Search All Service Accounts
-rbac-tool lookup -e '.*'
+rbac-tool lookup
+
+# Search Service Accounts that match myname exactly
+rbac-tool lookup myname
 
 # Search All Service Accounts that contain myname
 rbac-tool lookup -e '.*myname.*'
@@ -47,14 +50,17 @@ rbac-tool lookup -ne '^system:.*'
 			var re *regexp.Regexp
 			var err error
 
-			if regex != "" {
-				re, err = regexp.Compile(regex)
-			} else {
-				if len(args) != 1 {
-					re, err = regexp.Compile(fmt.Sprintf(`.*`))
+			if regex == "" {
+				if len(args) == 1 {
+					// exact match
+					re, err = regexp.Compile(fmt.Sprintf(`^%v$`, args[0]))
 				} else {
-					re, err = regexp.Compile(fmt.Sprintf(`(?mi)%v`, args[0]))
+					// search all service accounts
+					re, err = regexp.Compile(fmt.Sprintf(`.*`))
 				}
+			} else {
+				// regex match
+				re, err = regexp.Compile(regex)
 			}
 
 			if err != nil {