Add support for authenticating with env vars

README.md

@@ -15,7 +15,7 @@ Usage
 1. Install and configure Python and Boto (See: https://github.com/boto/boto)
 2. Create a SNS topic in AWS and copy the ARN into the config file
 3. Subscribe with a email address to the SNS topic
-4. Create a snapshot user in IAM and put the key and secret in the config file
+4. Create a snapshot user in IAM and put the key and secret in the config file (or set them as [environment variables](http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html#cli-environment))
 5. Create a security policy for this user (see the iam.policy.sample)
 6. Copy config.sample to config.py
 7. Decide how many versions of the snapshots you want for day/week/month and change this in config.py

makesnapshots.py

@@ -28,6 +28,7 @@
 import sys
 import logging
 from config import config
+from os import environ
 
 
 if (len(sys.argv) < 2):
@@ -69,8 +70,14 @@
 logging.info(start_message)
 
 # Get settings from config.py
-aws_access_key = config['aws_access_key']
-aws_secret_key = config['aws_secret_key']
+try:
+    # Try to load user-specified access keys from environment variables
+    aws_access_key = environ['AWS_ACCESS_KEY_ID']
+    aws_secret_key = environ['AWS_SECRET_ACCESS_KEY']
+except:
+    # Or from the config file (if ENV don't exist)
+    aws_access_key = config['aws_access_key']
+    aws_secret_key = config['aws_secret_key']
 ec2_region_name = config['ec2_region_name']
 ec2_region_endpoint = config['ec2_region_endpoint']
 sns_arn = config.get('arn')