Add login command to log in to a Portainer instance

Dockerfile

@@ -10,6 +10,7 @@ ENV PSU_AUTHENTICATION_PASSWORD="" \
   PSU_CONNECTION_URL="" \
   PSU_DEBUG="" \
   PSU_ENDPOINT_LIST_FORMAT="" \
+  PSU_LOGIN_PRINT="" \
   PSU_STACK_DEPLOY_ENDPOINT="" \
   PSU_STACK_DEPLOY_ENV_FILE="" \
   PSU_STACK_DEPLOY_REPLACE_ENV="" \

cmd/login.go

@@ -0,0 +1,34 @@
+package cmd
+
+import (
+	"fmt"
+	"github.com/greenled/portainer-stack-utils/common"
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+// loginCmd represents the login command
+var loginCmd = &cobra.Command{
+	Use:   "login",
+	Short: "Log in to a Portainer instance",
+	Run: func(cmd *cobra.Command, args []string) {
+		// Get auth token
+		authToken, authenticationTokenRetrievalError := common.GetNewAuthenticationToken()
+		common.CheckError(authenticationTokenRetrievalError)
+
+		if viper.GetBool("login.print") {
+			fmt.Println(authToken)
+		}
+
+		// Save auth token
+		configSettingErr := setConfig("auth-token", authToken)
+		common.CheckError(configSettingErr)
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(loginCmd)
+
+	loginCmd.Flags().Bool("print", false, "prints retrieved auth token")
+	viper.BindPFlag("login.print", loginCmd.Flags().Lookup("print"))
+}