Checkpoint

.gitignore

@@ -1 +1 @@
-json/
+_output/*.template

yaml/lambda.yaml → cloudformation/lambda.yaml.jinja

@@ -24,7 +24,7 @@
     LambdaFunction:
       Type: AWS::Lambda::Function
       Metadata:
-        Comment: A Lambda function to monitor running resources in AWS
+        Comment: A Lambda function to monitor running resources in AWS (updated comment)
       DependsOn: [MyLambdaExecutionRole]
       Properties:
         Code:

fabfile.py

@@ -1,5 +1,6 @@
 import boto3
 import glob
+import jinja2
 import json
 import os
 import yaml
@@ -12,8 +13,8 @@
 coloredlogs.install(level=logging.INFO)
 
 from fabric.api import task
+from fabric.contrib.console import confirm
 from fabric.utils import abort
-from pprint import pprint
 
 # Configure PyYaml to create ordered dicts
 _mapping_tag = yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG
@@ -31,34 +32,35 @@ def construct_yaml_ordered_map(loader, node, deep=False):
 
 yaml.add_constructor(_mapping_tag, construct_yaml_ordered_map)
 
-root_dir = os.path.dirname(__file__)
-json_dir = os.path.join(root_dir, 'json')
-yaml_files = glob.glob(os.path.join(root_dir, 'yaml/*.yaml'))
-json_files = glob.glob(os.path.join(root_dir, 'json/*.template'))
+ROOT_DIR = os.path.dirname(__file__)
+JSON_DIR = os.path.join(ROOT_DIR, '_output')
+JSON_EXT = '.template'
+YAML_FILES = glob.glob(os.path.join(ROOT_DIR, 'cloudformation/*.yaml.jinja'))
+JSON_FILES = glob.glob(os.path.join(JSON_DIR, '*{0}'.format(JSON_EXT)))
 
 
 @task(default=True)
 def render():
-    if not yaml_files:
+    if not YAML_FILES:
         abort('No YAML files present in directory')
 
-    if not os.path.exists(json_dir):
-        logger.info('Created directory: %s', json_dir)
-        os.makedirs(json_dir)
+    if not os.path.exists(JSON_DIR):
+        logger.info('Created directory: %s', JSON_DIR)
+        os.makedirs(JSON_DIR)
 
-    for yaml_file in yaml_files:
+    for yaml_file in YAML_FILES:
         with open(yaml_file, 'r') as yaml_contents:
             data = yaml.load(yaml_contents.read())
             json_str = json.dumps(data, indent=2)
-            json_file = os.path.join(json_dir, os.path.basename(yaml_file).split('.')[0]) + '.template'
+            json_file = os.path.join(JSON_DIR, os.path.basename(yaml_file).split('.')[0]) + JSON_EXT
             with open(json_file, 'w') as json_contents:
                 json_contents.write(json_str)
                 logger.info('Converted %s to %s', os.path.basename(yaml_file), os.path.basename(json_file))
 
 @task
 def validate():
     client = boto3.client('cloudformation')
-    for json_file in json_files:
+    for json_file in JSON_FILES:
         with open(json_file, 'r') as json_contents:
             try:
                 client.validate_template(TemplateBody=json_contents.read())
@@ -69,22 +71,40 @@ def validate():
 
 @task
 def launch(template_name=None, stack_name=None):
+
     if not template_name:
         abort('Must provide template')
     if not stack_name:
         abort('Must provide stack_name')
     client = boto3.client('cloudformation')
-    with open(os.path.join(json_dir, template_name + '.template')) as json_contents:
-        response = client.create_stack(StackName=stack_name,
-                                       TemplateBody=json_contents.read(),
-                                       Capabilities=['CAPABILITY_IAM'])
-        logger.info(response)
 
+    update = False
+    try:
+        resp = client.describe_stacks(StackName=stack_name)
+        message = 'Stack {0} exists, and is in state {1}. Proceed with update?'.format(
+            stack_name, resp['Stacks'][0]['StackStatus'])
+        if not confirm(message):
+            abort('Aborting.')
+        else:
+            update = True
+    except ClientError:
+        logger.info('No stack named {0}; proceeding with stack creation'.format(stack_name))
+
+    with open(os.path.join(JSON_DIR, template_name + JSON_EXT)) as json_contents:
+        if update:
+            response = client.update_stack(StackName=stack_name,
+                                           TemplateBody=json_contents.read(),
+                                           Capabilities=['CAPABILITY_IAM'])
+        else:
+            response = client.create_stack(StackName=stack_name,
+                                           TemplateBody=json_contents.read(),
+                                           Capabilities=['CAPABILITY_IAM'])
+        logger.info(response)
 
 
 @task
 def clean():
-    for f in json_files:
+    for f in JSON_FILES:
         os.remove(f)