check if file already exists

src/cli.ts

@@ -363,7 +363,11 @@ export function buildArgs(commands = lazy, wrapMainHandler = wrapCommandHandler)
     'init-stack-args',
     description('initialize stack-args.yaml'),
     (args) => args
-      .demandCommand(0, 0),
+      .demandCommand(0, 0)
+			.option('force', {
+				type: 'boolean', default: false,
+				description: description('Overwrite the current stack-args.yaml')
+			}),
     wrapMainHandler(commands.initStackArgs))
 
     .option('environment', environmentOpt)

src/initStackArgs.ts

@@ -1,6 +1,7 @@
 import * as fs from 'fs';
+import {Arguments} from 'yargs';
 
-export async function initStackArgs() : Promise<number> {
+export async function initStackArgs(argv: Arguments) : Promise<number> {
   // await configureAWS(argv.profile, argv.region);
   // Here we import the File System module of node
   const stackArgs = `# REQUIRED SETTINGS:
@@ -51,7 +52,17 @@ NotificationARNs:
 #   - make build # for example`
 
 
-  fs.writeFileSync('stack-args.yaml', stackArgs);
-  console.log("stack-args.yaml has been created!");
+	if (fs.existsSync('./stack-args.yaml') && !argv.force) {
+		console.log("stack-args.yaml already exists! Use --force to overwrite");
+		return 1
+	}
+	else {
+		fs.writeFileSync('stack-args.yaml', stackArgs);
+		if (argv.force) {
+			console.log("stack-args.yaml has been overwritten by a new one!");
+		} else {
+			console.log("stack-args.yaml has been created!");
+		}
+	}
   return 0;
 }

stack-args.yaml

@@ -0,0 +1,46 @@
+# REQUIRED SETTINGS:
+StackName: <string>
+Template: <local file path or s3 path>
+# optionally you can use the yaml pre-processor by prepending 'render:' to the filename
+# Template: render:<local file path or s3 path>
+
+# OPTIONAL SETTINGS:
+# Region: <aws region name>
+# Profile: <aws profile name>
+
+# aws tags to apply to the stack
+Tags:
+#   owner: <your name>
+#   environment: development
+#   project: <your project>
+#   lifetime: short
+
+# stack parameters
+Parameters:
+#   key1: value
+#   key2: value
+
+# optional list. *Preferably empty*
+Capabilities:
+#   - CAPABILITY_IAM
+#   - CAPABILITY_NAMED_IAM
+
+NotificationARNs:
+#   - <sns arn>
+
+# CloudFormation ServiceRole
+# RoleARN: arn:aws:iam::<acount>:role/<rolename>
+
+# TimeoutInMinutes: <number>
+
+# OnFailure defaults to ROLLBACK
+# OnFailure: 'ROLLBACK' | 'DELETE' | 'DO_NOTHING'
+
+# StackPolicy: <local file path or s3 path>
+
+# see http://docs.aws.amazon.com/cli/latest/reference/cloudformation/create-stack.html#options
+# ResourceTypes: <list of aws resource types allowed in the template>
+
+# shell commands to run prior the cfn stack operation
+# CommandsBefore:
+#   - make build # for example